# Lifestyles & Discussion > Freedom Living >  Biomass Gasification for Fueling Internal Combustion Engines

## buenijo

I did a search of the forums here and was surprised to see virtually no mention of wood gasification technology. So, I'm providing an introduction to the technology. Those who have read my other posts know that I'm particularly interested in small scale steam power with biomass fuel and extensive waste heat recovery. However, if suitable biomass fuel is available, you don't mind the fuel processing required, and electrical power delivered at a high rate is the primary goal, then wood gasification might be ideal. More important, the lack of suitable hardware for small scale steam power makes this the practical alternative.

These videos provide a good demo:

http://www.youtube.com/watch?v=mnjDq...eature=related
http://www.youtube.com/watch?v=FL7vj...eature=related

These videos provide more thorough explanation:

http://www.youtube.com/watch?v=qlq3_CCVniU (series of videos)

Some good publications: 

http://taylor.ifas.ufl.edu/documents...ne_Systems.pdf (probably the best single resource)
http://www.fao.org/docrep/t0512e/T0512e00.htm
http://www.woodgas.net/files/FEMA_em...y_gassifer.pdf (good for introduction only, as this design is known to produce a lot of tar)

Forums that discuss the technology:

http://driveonwood.com/forum
http://tech.groups.yahoo.com/group/WoodGas/

Some units available for purchase:

www.allpowerlabs.com
www.vulcangasifier.com
www.victorygasworks.com
www.garringergasifier.com
www.leafgenerator.com

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## Acala

Yes.  It seems that hundreds of thousands of vehicles in Europe were converted to run on wood gas during WWII.

I don't think it is very efficient, compared to using the same biomass to run a steam engine.  But if you already have a gasoline engine and you have no gasoline, wood gas seems like a serious alternative.

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## buenijo

> Yes.  It seems that hundreds of thousands of vehicles in Europe were converted to run on wood gas during WWII.
> 
> I don't think it is very efficient, compared to using the same biomass to run a steam engine.  But if you already have a gasoline engine and you have no gasoline, wood gas seems like a serious alternative.


The efficiency of these systems can be a complicated topic, particularly when so many definitions of "efficiency" exist. A small gas engine fueled by wood can see a net thermal efficiency of 15%, and 20% is possible under optimal conditions. This assumes the system is operated at or near its optimal efficiency, which tends to be a high output relative to its rated power. Efficiency under low part load conditions is generally much lower. By contrast, a typical small steam system sees 4 - 8%. A small steam system can be a lot more efficient, but not without some more complicated engineering. So, if wood is the desired fuel, and high power levels are desired, then the gas engine is the more efficient option. Things get a lot more complicated under real world conditions. In the end, it all depends on the application.

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## buenijo

(I copied this from the victorygasifier.com site. I think the "Hotwatt" system that Ben Peterson developed is very nice. In particular, I applaud his emphasis on waste heat recovery. I like the technology, and I love Mr. Peterson's design. However, it seems clear to me that very few people have access to enough suitable biomass fuel to power this system as a primary home power plant. There's a niche for this technology, but photovoltaics and wind power should provide a core renewable power base for electricity -  at least where it's cost effective. One thing's for sure... no "lazy man" would be interested in this system.)

http://victorygasifier.com/24-hour-power/
The Lazy Man’s Approach to 24 Hour Heat & Power
By Ben Peterson

"Lot’s of folks think that to get 24 hour heat and power you need to run 24 hours a day. Not only is this impractical, time consuming and just plain “no fun.” It’s not necessary. The Hotwatt philosophy to 24 hour heat and power is to convert a small amount of your wood waste into usable fuel gas to power engines, then store that heat  and electricity for use through the day. Did you know that most of the energy we make is just wasted as lost heat or line transmission losses? Wood, even waste wood is a resource. Why use more than you have to. We would like to see our customers using around 2 acres of their land to provide all of their heat and power needs for the entire year. Alder is a good crop if you are starting from scratch.



Pictured above is the Hotwatt coupled to a genset for power and a water heat storage tank to store waste heat. Behind the Hotwatt is a mobile battery pack for this demonstration.



So back to our lazy man approach.

One day a month you gather your branches, pallets, or other feedstock and get it prepared for the gasifier by sizing and drying it to spec. Bag it up and set it to the side. If you aren’t prepared to invest one day a month prepping your feedstock, then this technology might not be for you. 
When you wake up in the morning you simply fill the Hotwatt with a load of wood, then press start. Pour yourself a cup of coffee and come back to start up the genset and go back to your day. 
The Hotwatt powered genset will recharge your battery pack while the forced hot air heats your home. Perform your most load intensive tasks while the engine is running so that you don’t drain your batteries. The residual stored heat and power will be used throughout the day to maintain your comfort. After a few hours the system will shut off based on the timer settings. 
In the evening you walk over to the unit and repeat step 2.(coffee optional) The house is then brought up to temperature again for the night and the batteries are again recharged. 
By harvesting every scrap of energy stored in the wood you can use much less than you think. By running the engine around 4 hours per day you can greatly extend its life and lower your service costs and any noise.

With very little effort you are now in charge of your own grid. It’s operating at just above the cost of your time and it’s in balance with nature. Simple.

Please note that we sell only the Hotwatt and genset at this time. Batteries are easily purchased locally from an off-grid supplier and hot water storage tanks are available on the internet. Set-up costs should include a plumber and an electrician.

Thanks for reading!"

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## Acala

> The efficiency of these systems can be a complicated topic, particularly when so many definitions of "efficiency" exist. A gas engine fueled by wood will see a net thermal efficiency of about 15%, and 20% is possible. This assumes the system is operated at its optimal efficiency, which tends to be a high output relative to its rated power. By contrast, a typical small steam system sees 5-8%. A small steam system can be a lot more efficient, but not without some really complicated and expensive engineering. So, if wood is the desired fuel, and high power levels are desired, then the gas engine is the more efficient option. Things get a lot more complicated under real world conditions. In the end, it all depends on the application.


I have not done any study of the subject, but where the loss of energy seems to be in a wood gas system is in all the heat used to produce the hot, bare carbon.  In other words, when you put wood in your gasifier, much of the heat generated by the burning of the cellulose, which happens entirely in the gasifier, is lost.  I think some is recovered in the breaking of the h-o bonds, but my understanding is that the gasifiers run HOT!.  A good steam boiler would capture most of that.  But then lots of heat escapes a steam engine with the exhaust.

So I guess I don't know.

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## danda

I looked into wood gasification briefly because I would like to use it to power our tractors and such.  However, I wanted to generate the gas, store it, and use it later....  and it seems that wood gasification is not good for that, though I forget why exactly.   They all strongly recommend running the engine directly off the gasifier, which means it must be physically on board the vehicle.  ick.

Now for a home genset, i can see where wood-gas could be more practical.  The pics and article above are pretty cool.

Has anyone heard of storing the gas and using it later on demand?  Or can you explain why that is a bad idea?

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## Dr.3D

> I looked into wood gasification briefly because I would like to use it to power our tractors and such.  However, I wanted to generate the gas, store it, and use it later....  and it seems that wood gasification is not good for that, though I forget why exactly.   They all strongly recommend running the engine directly off the gasifier, which means it must be physically on board the vehicle.  ick.
> 
> Now for a home genset, i can see where wood-gas could be more practical.  The pics and article above are pretty cool.
> 
> Has anyone heard of storing the gas and using it later on demand?  Or can you explain why that is a bad idea?


If wood gas is anything like coal gas, it can be stored in an inverted barrel, submerged in water.   The biggest problem with this is having to anchor a cylindrical basket around the floating drum to keep it from falling over.     The more gas you want to store, the bigger or more drums you need.    When I was a kid, they had some that were 100 feet in diameter and 7 stories high.   They had a rather expensive cage built around them to keep the drum from falling over.     

Here is a picture of one of the smaller ones.   Might be a little big for one home.

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## Deborah K

Biomass Gasification??  Sounds like what my poor husband goes through every time he eats chili.

sorry

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## Dr.3D

> Biomass Gasification??  Sounds like what my poor husband goes through every time he eats chili.
> 
> sorry


LOL, that's azz gaz.... I understand it is similar to wood and coal gas though, in that is contains some methane.
BTW.... it's usually harder on those around the person suffering from azz gaz than it is on the sufferer.

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## buenijo

> I have not done any study of the subject, but where the loss of energy seems to be in a wood gas system is in all the heat used to produce the hot, bare carbon.  In other words, when you put wood in your gasifier, much of the heat generated by the burning of the cellulose, which happens entirely in the gasifier, is lost.  I think some is recovered in the breaking of the h-o bonds, but my understanding is that the gasifiers run HOT!.  A good steam boiler would capture most of that.  But then lots of heat escapes a steam engine with the exhaust.
> 
> So I guess I don't know.


Hi Acala. I edited the orginal post to add some publications available online. The first one I added ("Handbook of Biomass Gasifier Engine Systems") is probably the single best resource there is.

The thermal losses from a good gasifier are roughly 20-30% (with the lower value achieved through insulation and heat regeneration where combustion air is preheated by the hot fuel gases). Conventional steam boilers have similar losses in the furnace exhaust, but they can get better than this. The very high temperatures in a gasifier are achieved through limited combustion in a very small volume, and a good gasifier will have excellent insulation to maintain high temperature. The thermal losses that do occur are mostly those associated with cooling the gas before it moves into the engine. 

The high temperature in the gasifier converts the solid structure of the fuel to a vapor (mostly CO, H2, CO2, H2O vapor, and tar vapors), and this forms charcoal in the process. Most of the tar vapors are burned to provide the high temperatures. Those tar vapors that cannot be burned will pass through the hot charcoal bed. Most important to understand is that endothermic reactions take place where much of the heat is converted to chemical energy(*). The primary fuel gases produced are carbon monoxide and hydrogen. 

The primary reason for the higher thermal efficiency of a gasifier engine system is the higher temperature, higher expansion ratio, and heat added during gas expansion (due to fuel combustion during the power stroke) in the gas engine vs. the conventional steam engine. Still, I believe a good small steam system has advantages over biomass gasification in a home power setting for its ability to use a much wider range of biomass fuels with less processing, superior waste heat recovery, relative simplicity, and its ability to operate quietly at very low power levels. Unfortunately, while it's possible for steam to do this, it's going to take some clever engineering combined with a lot of money to make a system competitive with a good wood gas engine system.

(*) The endothermic reactions include the formation of CO and H2 from C (charcoal) and H2O (water vapor from combustion gases), the formation of CO from C (charcoal) and CO2 (from combustion gases), and the cracking of tars (a minor component). So, while a lot of the volatiles are combusted in the system, very little of the charcoal (i.e. carbon) is combusted (the free oxygen is consumed in the combustion of volatiles). Rather, the hot charcoal that remains reacts with combustion products of the volatiles (CO2 and H2O) to generate more fuel gas. In other words, the system converts most of the combustion heat to chemical energy.

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## buenijo

> If wood gas is anything like coal gas, it can be stored in an inverted barrel, submerged in water.   The biggest problem with this is having to anchor a cylindrical basket around the floating drum to keep it from falling over.     The more gas you want to store, the bigger or more drums you need.    When I was a kid, they had some that were 100 feet in diameter and 7 stories high.   They had a rather expensive cage built around them to keep the drum from falling over.     
> 
> Here is a picture of one of the smaller ones.   Might be a little big for one home.


Dr.3D, thanks for the great post! I am aware of wood gas being stored in large latex weather balloons (see video here: http://www.youtube.com/watch?v=0xmRW...el_video_title). Here's another example: http://www.youtube.com/watch?v=ilwyfzUo7tU (make sure to read the comments that he provides).

Personally, I don't think storing the gas is practical for anything other than intermittent low power applications as the energy density of wood gas is so low. Using a latex balloon is a reasonably good idea primarily because trying to compress a low energy gas like wood gas would consume too much energy.

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## Dr.3D

> Dr.3D, thanks for the great post! I am aware of wood gas being stored in large latex weather balloons (see video here: http://www.youtube.com/watch?v=0xmRW...el_video_title). Here's another example: http://www.youtube.com/watch?v=ilwyfzUo7tU (make sure to read the comments that he provides).
> 
> Personally, I don't think storing the gas is practical for anything other than intermittent low power applications as the energy density of wood gas is so low. Using a latex balloon is a reasonably good idea primarily because trying to compress a low energy gas like wood gas would consume too much energy, and probably result in a negative energy balance.


This sort of storage only uses the weight of the drum to create pressure on the gas.   As the gas is used, the drum moves downward and when it is empty, the top of the tank(drum) is level with the ground.   It's just floating in a pit full of water and when it is full, the top is level with the top of the support cage.   At one time, there were hundreds of those coal gas storage tanks.  Great for stationary storage, but for a moving vehicle, the best, most condensed storage is the (wood) fuel itself.  This is why they tend to mount the generator on the truck.

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## buenijo

> This sort of storage only uses the weight of the drum to create pressure on the gas.   As the gas is used, the drum moves downward and when it is empty, the top of the tank(drum) is level with the ground.   It's just floating in a pit full of water and when it is full, the top is level with the top of the support cage.   At one time, there were hundreds of those coal gas storage tanks.  Great for stationary storage, but for a moving vehicle, the best, most condensed storage is the (wood) fuel itself.  This is why they tend to mount the generator on the truck.


I like the idea. Your posts have got me thinking... I suppose I'll share my thoughts: Most off grid homes should take advantage of a PV array and/or wind turbine where conditions are optimal. After all, these consume no fuel. I consider the great value of a biomass gasifier as a means to augment these systems, particularly in providing for heating applications. However, gasifier engine systems present a problem when used for home power. Air has to move through the gasifier at a high rate to maintain the high temperature necessary for producing a quality gas. In the off grid home, this means intermittent operation of the gasifier at a high rate. Putting all the waste heat to use under these conditions would be difficult. Storing the gas will provide a combustible gas for both heating applications and electrical power generation. Furthermore, with the generator operated at a lower rate, more of its waste heat can be put to use in heating applications (such as heating water). Basically, I'm thinking that a large gas storage system could allow for more efficient use of the limited biomass fuel available. Perhaps a small generator could be automated to back up a battery system. Perhaps such a configuration could allow for a much smaller battery system. Lots of possibilities come to mind.

ADDENDUM: Unfortunately, wood gas has about 1/8 the energy density of natural gas. According the specs on the Hotwatt, it provides up to 35 cubic meters of gas over one hour (equal to 1236 cubic feet per hour) . With the average energy density of this gas at about 125 btu/cf, the storage vessel would have to be enormous. After some consideration, I don't think it's practical.

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## Anti Federalist

Great information in this thread, thanks for posting buenijo.

I have looked into the gasification side as well, but I still maintain that micro steam will be the cheapest, most efficient and fuel versatile (whatever will burn will make steam) option of three tiered, off grid, fully self contained home electric power grid.

PV, wind and steam, all charging a large bank of D8 batteries as needed and a 240/120VAC inverter.

Any wood gas project I'd get involved with would be one that is geared toward mobile internal combustion engine uses: car, truck, tractor.

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## buenijo

This is not directly related, but I thought I'd share. I came across one of these generators operated at work recently. Let me tell you, this thing is so quiet it's eery. Also, the owner of the generator has used it several times a week for several hours at a time over a two year period with 100% reliability. Seems like a winner to me.

http://www.hondapowerequipment.com/p...elid=EU2000IKN

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## buenijo

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## buenijo

> Great information in this thread, thanks for posting buenijo.
> 
> I have looked into the gasification side as well, but I still maintain that micro steam will be the cheapest, most efficient and fuel versatile (whatever will burn will make steam) option of three tiered, off grid, fully self contained home electric power grid.
> 
> PV, wind and steam, all charging a large bank of D8 batteries as needed and a 240/120VAC inverter.
> 
> Any wood gas project I'd get involved with would be one that is geared toward mobile internal combustion engine uses: car, truck, tractor.


Hello Anti Federalist! I'm gonna have to agree with you, ;-). Still, in my opinion, it would take a well-engineered, mass-produced, biomass-fueled small steam system to make the advantages more clear for most people. Unfortunately, most people do not have much of an imagination.

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## AFPVet

> Biomass Gasification??  Sounds like what my poor husband goes through every time he eats chili.
> 
> sorry


ROFLOMAO! That was good!

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## buenijo

While reviewing the specs on the Hotwatt gasifier unit I came across what is clearly an error. It is claimed that "2.5 pounds of wood is equal to 1 kilowatt hour of electricity". I checked the specs on the Kubota engine that the system uses. The thermal efficiency is listed at 22% with natural gas. It should see a similar efficiency with wood gas. However, the thermal losses from the gasifier will reduce the net efficiency by about 25% to 16.5%. This is what I expect from a good gasifier engine system using quality fuel, and this figure can be verified from the publications that I provided links for. Wood at 20% moisture content (as described in the Hotwatt specs) has about 6900 btu/pound. Therefore, 2.5 pounds will provide about 17,250 btu. The shaft power of the engine at 16.5% net thermal efficiency would be equal to 2850 btu, or 0.835 kw hr of mechanical energy. Now, if we assume 75% efficiency in the alternator (which is generous), then the amount of electricity generated from the alternator is 0.626 KWh. Next, this system is operated intermittently to charge a lead acid storage battery. Losses in charging/discharging amount to about 20%, and this brings the figure down to 0.501 KWh. Finally, an inverter is about 85% efficient. In the end, that 2.5 pounds of wood at 20% moisture will provide 0.426 KWh of ac electricity from the inverter. Interestingly, 2.5 *kilograms* of wood (as opposed to 2.5 pounds) would provide about one KWh of electricity after factoring in the losses I listed. So, it looks like an honest mistake to me.

ADDENDUM: After a bit of research, I'm convinced that the fuel consumption spec for the Hotwatt is not an "honest mistake". However, I do believe that it's less than honest. It's possible to generate 1 kwh of electricity with a good wood gas engine system from 2.5 pounds of bone dry wood if a high quality engine is coupled directly to a high quality generator head, and the system is operated where the efficiency is optimal. The problem with listing this figure is that these conditions are extremely unlikely to hold for the end user. It compounds the error to list such a figure with "biomass" at "20% m.c." (i.e. moisture content). It is particularly egregious to list such a figure when the Hotwatt is configured and sold as a battery charging system that would include additional losses in alternators, battery, and inverter.

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## buenijo

Just sharing my thoughts again on the efficiency of these gasifier engine systems. I checked the specs on the gek gasifier system. They claim 1 KWHe produced from 2.64 pounds of biomass (they didn't write what form or moisture content). Their system is designed to drive a generator head for direct ac power, and this would have fewer losses than a battery/inverter system (assuming the generator is used in high power applications). NOTE: Using wood with zero moisture combined with the Kubota engine directly coupled to a quality generator head could achieve those numbers under optimal conditions. However, in the real world these numbers are useless. 

ADDENDUM: I spoke with an engineer at All Power Labs. He took my information and promised to look into it and get back to me. I'll share any results with the forum.

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## buenijo

COMPRESSING WOOD GAS

I've always heard that compressing wood gas would require too much energy, but I never took the time to verify the claim. I searched various sites for compressor specs to get cfm/hp figures. Here is one that I found: http://www.truetex.com/aircompressors.htm. The source states: "A good single-stage compressor, per true HP input, will deliver about 4 true CFM at 100 psig. It is not uncommon to see this more like 3 CFM per HP." 

OK, we know that one cf of wood gas has 125 btu of energy. So, compressing wood gas for one hour from atmospheric to 100 psig at a rate of 3 CFM will store 22,500 btu worth of wood gas. An engine at 17.5% net efficiency powered by wood gas and directly coupled to a compressor will consume 14,500 btu worth of wood gas to deliver one hp at the shaft over one hour. 40% of the energy is lost. 

So, the process is very wasteful. More important, even at 100 psig gas storage a tank would have to be very large to store a useful amount of gas. So, it would also be too expensive and dangerous. One would be dependent on a compressor, and introducing impurities into a pressure vessel would compromise the integrity of the vessel. Finally, wood gas is about 20% carbon monoxide. 2-3% can kill. One lung full of wood gas can be lethal. CONCLUSION: Compressing wood gas is not worth it. In fact, storing it is just a bad idea. It must be consumed at the point of generation.

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## buenijo

I just got a response from All Power Labs:

"The 1.2 kg/kWh reported is on a bone dry basis
Bone dry wood is reported as around 5.56 kWh/kg (20 MJ/kg).
So, we're using 1.2 kg * (5.56 kWh/kg) / 1 kWh = 6.672 kWh in / 1 kWh out. 1 kWh out/6.672 kWh in= 14.9% eff.
The last endurance test we ran was based on fuel with an average 20% MC, and took 1.5 kg/kWh @ 20% MC. 
The calculated efficiency he found from the last run was around 15-16%. We should be posting this data on the website as soon as we have time to organize it into something presentable."

NOTE: 5.56 kWh/kg is equal to 8620 btu/pound.

MY COMMENTS: Looks like I was right. The numbers were based on wood with zero moisture (i.e. "bone dry"). These efficiency values are within reason for an efficient generator head directly coupled to the Kubota engine operated at an optimal speed and output. However, in the off grid setting the efficiency specs should consider real world losses. For example, battery and inverter losses would bring the net efficiency for electricity generation down to 9-10%.

ADDENDUM: See next post. The efficiency of gas engines vary greatly over their power range. Therefore, a wood gas engine system operated at a low part load (less than or equal to 25% rated output), and used in a battery charging configuration w/inverter, would see a net efficiency for electricity generation on the order of only 5%.

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## buenijo

Here's a good example to show how the efficiency of an engine can vary greatly over its power range. See the following specs on a Kohler natural gas generator here: http://kohlerpower.com/residential/d...&prodnum=54561. Here is the table in question:

Standby Fuel Consumption at   
100% load:  3.7 m³/hr (132 cfh)  
75% load:  3.2 m³/hr (113 cfh)  
50% load:  2.6 m³/hr (93 cfh)  
25% load:  2.2 m³/hr (77 cfh)

The fuel consumption rate at 25% load does not fall by a factor of four, but only by less than a factor of 2. Therefore, the efficiency at 25% load is well under half the efficiency at 100% load. The engine is about 25% efficient at 100% load, but only about 11% efficient at 25% load. This can make a dramatic difference in the fuel consumption rates depending on how the system is configured. In fact, generators are normally operated at a low part load. Therefore, expect more than twice the fuel consumption rates in the real world as compared to what optimal figures show. In fact, when one factors in the thermal losses from the gasifier of a wood gas engine system, the net thermal efficiency is going to fall to well under 10% for anything under 25% rated power. That's equal to a good compounded piston steam engine using relatively low pressure saturated steam.

The efficiency of a wood gas engine system used for home power could be improved a great deal by operating the engine at a much lower speed while battery charging at a lower rate, and while using as much of the electricity as possible real time while the battery is charging as this will avoid a lot of battery losses. However, you can't go too low an output otherwise there's a risk of dropping temps in the gasifier which will cause it to start making a dirty gas. Also, the lower speeds will reduce friction losses, but then there will be greater thermal losses from the cylinder walls. It's kind of a catch 22 (however, the friction losses at high speeds is the greater loss). Perhaps the best solution if someone insists on using a wood gas engine system is to go with a slow speed Diesel that is dual-fueled with wood gas. Ken Boak (google Ken Boak Lister) converted a slow speed Lister Diesel to 100% wood gas operation by installing a spark plug and ignition system. However, a Diesel can be operated with wood gas by admitting wood gas along with the intake air. In that configuration the existing governer is retained to control the Diesel fuel consumption. Basically the wood gas added to the air stream is combusted along with the Diesel fuel, but the governor only cares about the speed of the engine. Therefore, it just sends less Diesel fuel to the injector on each power stroke after wood gas is added. If properly configured this kind of system reduces Diesel fuel consumption by 90% (that is, it uses only about 10% of the Diesel normally required). Also, the Diesel requires no modification, so you can always go back to 100% Diesel fuel at any time. http://alternativefuels1.tpub.com/0276/02760119.htm

ADDENDUM: Just more info on converting a Diesel to wood gas. The air intake on a Diesel engine is not throttled. Therefore, there is very little vacuum on the intake manifold. Therefore, there is not the differential pressure necessary to draw gases through the gasifier and filter train. The solution is to throttle the air intake. The supply of wood gas can then be connected directly to the intake manifold where it will mix with the incoming air. Diesel is provided to the injectors by the existing governor system as a function of engine speed (assuming a constant speed generator application). There is a problem with this kind of set up. If the engine is operating a load that suddenly falls, then an overspeed condition is likely if the wood gas supply is not controlled. In the case where a Diesel automobile is fueled by wood gas, then operator would throttle the air supply to the engine to vary output with the lowest throttle setting corresponding to an idle speed that provides just enough vacuum to draw a minimal amount of air into the gasifier to keep it at a proper temperature. Throttling down on the air supply would increase the manifold vacuum, and this would in turn draw more wood gas from the gasifier (the Diesel normally admitted on each cycle for idle should provide ignition).  NOTE: It's also possible to fix the air supply throttle valve, then control the position of the wood gas valve. In a stationary setting I have heard of cases where a centrifugal governor is used to control the air supply valve and the Diesel supply is fixed at what is normally supplied during idle. Therefore, in that case if the load is dropped the governor will open the air valve until only air and minimal Diesel is admitted to support idle. The simplest kind of stationary (unattended) set up would be to just connect the gasifier to the intake manifold while throttling down on the air supply, then using the generator to power a constant load. However, there should be a means to shut the supply of wood gas should an overspeed condition occur. My research suggests that preignition is likely for wood gas if the compression ratio exceeds 17:1. Many Diesels today have compression ratios greater than 20. Also, only direct injection Diesels do well on wood gas, but the good news is that most Diesel are direct injection these days. It's possible to lower the compression ratio on a Diesel by using thicker gaskets, and I have seen a case where a copper gasket was fashioned for this purpose, and it worked well. Also, when throttling down on the air supply it may be that a higher compression ratio can be used because the manifold vacuum will restrict the admission of gases into the cylinder and moderate the peak compression temperatures, and operating a Diesel at part load might help for the same reason. So, I speculate that operating an unmodified small Diesel genset with wood gas can be done at part load.

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## osan

> Those who have read my other posts know that I'm particularly interested in small scale steam power with biomass fuel and extensive _waste heat recovery_.


Heat greenhouses in cold climates.

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## buenijo

> Heat greenhouses in cold climates.


Good idea. How about a large store of water in the green house as the heat sink for the condenser? This would provide a thermal mass while also increasing humidity levels during the winter months. Also, the combustion products can be used to dramatically increase both CO2 and water vapor within the greenhouse which would absolutely increase yields (particularly due to the CO2 increase).

Other uses for the heat that I've considered beyond water heating and space heating include: water distillation, water pasteurization, food drying, clothes drying, and drying biomass fuel - although, there should be enough heat from the furnace exhaust to dry the biomass fuel on demand. I've also considered heat-powered a/c and refrigeration, but I'm now convinced that saturated steam near atmospheric pressure is not the best heat source for this. These should have a higher temperature for optimal results (so, use a small biomass furnace directly for this). On that note, I'm confident that a biomass furnace at only 24,000 BTU/hr can power a simple one-cycle ammonia absorption a/c unit at one refrigeration ton (i.e. 12,000 BTU/hr cooling rate). I've also considered a batch loaded biomass-fueled system for powering a large ammonia absorption freezer. I'm particularly interested in the ammonia absorption systems because these would dramatically reduce electrical loads in the off grid setting. The idea I have in mind is to reduce electrical loads to the point that a moderate PV system can reliably take the loads with a small steam system provided only as a back up generator and heat source.

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## osan

> Good idea. How about a large store of water in the green house as the heat sink for the condenser? This would provide a thermal mass while ]
> also increasing humidity levels during the winter months.


Sure.  The more the better.  50K-100K gallons embedded in the earth would be a great sink @ say, 140* with a feed to the household water heater.  Run piping to radiators, year-round growing season.  I would love to get 1/4 acre under glass.  Damned expensive these days.




> Other uses for the heat that I've considered beyond water heating and space heating include: water distillation, water pasteurization, *food drying*,


That is another top-notch application.




> I've also considered a batch loaded biomass-fueled system for powering a large ammonia absorption freezer. I'm particularly interested in the ammonia absorption systems because these would dramatically reduce electrical loads in the off grid setting. The goal I have in mind is to reduce electrical loads to the point that a moderate PV system can reliably take the loads with a small steam system provided only as a back up generator and heat source.


I am not well versed in AC - may I take it that ammonia systems are more efficient than freon?

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## buenijo

> I am not well versed in AC - may I take it that ammonia systems are more efficient than freon?


 It depends on how one defines "efficiency". Taking electricity or mechanical energy as a given, the vapor compression cycle is certainly the most efficient option. However, the off gridder cannot produce electricity nor shaft power easily. However, heat is more readily available. I believe that an ammonia absorption system can be superior in the off grid setting, especially when biomass fuel is used. However, modern food refrigeration appliances are both efficient and reliable, and there's a good argument for retaining these in an off grid home... but air conditioning is a different argument. If the off gridder wants a/c, then I see no option more promising than the biomass-fueled ammonia absorption system. NOTE: To me, "off grid" means not merely no grid electricity, but no refined fuels either (total energy self sufficiency).


ADDENDUM: I am now more optimistic about conventional vapor compression a/c systems powered by photovoltaics. Some modern a/c units are highly efficient like split ductless systems with variable speed compressor motors. Also, a low power engine system that operates for long periods can be used to power a refrigerant compressor directly (i.e. mechanically) to eliminate generator and motor losses otherwise seen in conventional systems.

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## buenijo

Just a discussion of a/c and refrigeration so that everyone here can appreciate the potential of ammonia absorption systems in an off grid setting. Fundamentally, all refrigeration cycles have the same purpose: to evaporate a liquid refrigerant at a relatively low pressure thereby making things cold, then turn the refrigerant vapor back into a liquid so the cycle will continue. The vapor compression cycle is used in just about everything these days. Here a compressor sends the refrigerant vapor into condenser coils at a high pressure. At this higher pressure the vapor will condense to a liquid. The heat emitted during this process is normally just dissipated to outside air (like the condenser unit for the a/c system that is placed outside, or the coils on the back of a refrigerator). The now liquid refrigerant at high pressure moves through a restrictor valve into the evaporator coils. The lower pressure in the evaporator coils causes the refrigerant to flash back to vapor thereby cooling the evaporator coils in the process. The vapor then enters the compressor to begin the cycle anew.  

By contrast, the ammonia absorption cycle uses a water/ammonia solution. This liquid solution is pumped to high pressure heater coils to be vaporized by the heat source. The vapor then goes into a separator (actually, a very simple device). Hot water drains from the bottom of the separator, and ammonia vapor leaves the top. The ammonia vapor goes to a condenser coil where it cools off to become liquid ammonia. The liquid ammonia then moves through a restrictor valve to enter the evaporator coils. The lower pressure in the evaporator coils causes the ammonia to flash to vapor thereby cooling the evaporator coils in the process. Next, the ammonia vapor enters the absorber tubes. However, first know that the water draining from the separator goes to the top of the absorber tubes via a small restrictor valve (note: the hot water leaving the separator first passes through a small heat exchanger to preheat the ammonia/water solution leaving the pump... this improves efficiency a great deal). The now cool water sprays into the top of the absorber tubes, then trickles down to the bottom. Water has a high affinity for ammonia. Therefore, it slowly absorbs the ammonia vapor as it moves through the absorber tubes. However, it's necessary to keep this absorber tubing as cool as possible during the process as water holds a lot more ammonia at low temperatures, and the absorption process releases heat. At the end of the absorber tube the liquid water/ammonia solution is re-established, and the solution moves to the pump to start the cycle anew. NOTE: The mechanical energy required from the ammonia/water pump is about 20 fold less than that required from a vapor compression cycle of the same capacity.

Basically, since electricity is precious in the off grid setting, any configuration that minimizes its consumption should be favored. 

NOTE: It is possible to operate the ammonia absorption system without a pump such that it has literally no moving parts. However, this requires that the many heat exchangers in the system be very precisely sized and positioned relative to one another in order to allow natural circulation to drive the flow. Also, part of the system has to be charged with a low density gas like H2 or He. This configuration relies on Dalton's law of partial pressures to cause the liquid ammonia to flash to vapor at a relatively high pressure (basically, think of the total pressure in the system as coming from both ammonia vapor and the low density gas... the latter takes up most of the volume, so it provides most of the pressure... the effective ammonia vapor pressure can be driven so low under these conditions that liquid ammonia flashes to vapor achieving the same cooling effect, but at a relatively high pressure). Most are familiar with RV refrigerators that are powered by heat... well, now you know how they work. 

DOWNSIDE: Copper cannot be used with ammonia... you'd have to go with steel (preferably stainless steel tubing and a steel separator vessel). However, note that aluminum tubing can be used with ammonia.

ADDENDUM: Thermal chillers that use water as the refrigerant operate at a high vacuum, and these can use absorbents that are less toxic (such as lithium bromide or silica gel). The electricity consumption rates are similiar to ammonia absorption systems, but without the toxic side effects and high pressure of ammonia. Still, a high vacuum presents other difficulties. NOTE: I have since experimented with generating a very high vacuum and found that it's not terribly difficult to generate and maintain if the system is fairly small. I also confirmed that magnetic drive centrifugal pumps work perfectly under a high vacuum. So, water could be circulated easily under the high vacuum of such a system without fear of breaking vacuum since these pumps are hermetically sealed.

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## buenijo

Interesting excerpt from Ken Boak's site: http://www.powercubes.com/listers.html

"The 200 litres of chips should produce 25kWh of electricity and 60kWh of hot water. As this household uses about 7.5kWh of electricity per day, the surplus can be used for heating the workroom and workshop." NOTE: The hot water is used for space heating.

This is a good example to illustrate some of the problems I see with wood gas engine systems for use in the off grid setting. I can't help but think a small steam system would be more appropriate here. Clearly the higher thermal efficiency of the Lister is wasted with 70% of the electricity generated used in space heating. A steam system would make more of the waste heat available in the steam exhaust, the wood fuel would not have to be processed so much, a wider range of biomass fuel sources could be used, and a good steam engine would still provide more than enough electricity in this setting while operating at a small fraction of the speed and hp of the Lister (it would be quieter too). In this case it seems that Mr. Boak must operate the system at a high rate to provide the required space heating during winter months. However, it is possible that the system cannot operate reliably at a much lower rate. As I've written before, air must be drawn through the gasifier at a minimum rate to maintain the required temperature, otherwise tar production is likely to increase. My research suggests that it's possible to operate gasifier engine systems at a lower rate, but not without using small regularly sized particulate biomass (like quality wood pellets, or similar forms) and/or using charcoal. Unfortunately, being forced to use highly processed biomass like wood pellets is problematic for obvious reasons, and charcoaling biomass loses more than half the energy content of the biomass fuel.

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## pcosmar

Every time I see this thread I think of Rush Limbaugh.

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## sparebulb

> Every time I see this thread I think of Rush Limbaugh.


Limp Windbag, alone, could propel this thing across the pacific on his strategic fat reserve.


Biodiesel Powered Boat Makes World Record Attempt *Using Human Fat As Fuel*
Save

earthrace

This isnt the first attempt Â at the world record for global circumnavigation by Pete Bethunes EARTHRACE; a futuristic looking watercraft heralded as the fastest eco boat on the planet.Â  According to this article in The Daily Mail

    Bethune and his wife mortgaged their house and sold everything they own to help make the project happen, while continuing to seek support from sponsors.

    Demonstrating further commitment to the cause, Bethune underwent liposuction and donated enough to produce 100ml of biofuel, while two other, larger volunteers also had the procedure, making a total of 10 liters of human fat.

    This in turn produced seven liters of biofuel, which could help the boat travel about 15km.

Which I think is probably a first forwellanyone or anything.



The first attempt at setting a world record started in Barbados on March 10, 2007 but it ended in tragedy as the boat collided with a fishing boat near Guatemala killing one of the boats crew.Â  The Earthrace and crew were held for 10 days while awaiting a judges decision on the accident.Â  All were eventually cleared but by that time they had failed in their attempt.Â  Then theÂ second attemptÂ was launched; this timeÂ leaving from San Diego on April 3rd, 2007 but had to be aborted when a crack was discovered in the hull.

But people who are willing to liposuction fat out of their bodies for fuel are not the type to give up at something like a cracked hull.Â  In March of 2008 the Earthrace will again set out from Spain in an attempt to set the world record for global circumnavigation; all the while contributing zero carbon to the atmosphere.Â  Lets hope that the third times the charm.

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## buenijo

Good video illustrating the basic principles of biomass gasification: http://www.youtube.com/watch?v=-ukKHTgiNsE. Imagine how much energy is wasted in a typical camp fire or even fire place.

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## buenijo

Listen to these interviews of Steven Harris. 

This man has genuine knowledge, experience, and common sense about alternative energy:

http://www.thesurvivalpodcast.com/tag/steven-harris

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## buenijo

I just became aware of a new small wood gasifier available for purchase. The price point on this unit is far lower than most others. I can't say anything about the quality of this unit. However, if anyone has considered purchasing a unit, then a low cost unit like this seems a good candidate. Anyway, check it out here at www.vulcangasifier.com. 

Here are some interviews of the individual who builds the units: 
http://www.youtube.com/watch?v=Eu7ToGp0FlA (interview starts at 46:15).
http://www.youtube.com/watch?v=gnDwUXQKLlQ

Vulcan powering a 4000 watt genset at 1500 watt load:
http://www.youtube.com/watch?v=l-uLwejWSVc

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## buenijo

Good video series on building a FEMA gasifier. He demonstrates its operation by powering a very small generator rated at only 750 watts. He is using wood pellets:

http://www.youtube.com/watch?v=nhMyc...eature=related
http://www.youtube.com/watch?v=0atat...eature=related
http://www.youtube.com/watch?v=4xJqz...eature=related
http://www.youtube.com/watch?v=aXi_-...eature=related
http://www.youtube.com/watch?v=tPUlY...eature=related
http://www.youtube.com/watch?v=K-Noc...eature=related
http://www.youtube.com/watch?v=Oxrc6d08sbk
http://www.youtube.com/watch?v=C1nC0...eature=related
http://www.youtube.com/watch?v=uKVRj...eature=related

A few more points I've uncovered about wood gasification. Using the engine exhaust to dry the fuel can also drive off all the water and some of the volatiles that are responsible for forming tar. Using a dry fuel should result in higher temperatures that would crack whatever tars remain. I have yet to see direct confirmation of the following, but I suspect that a simple FEMA gasifier could power a reliable wood gas engine system if small wood chips are processed in this manner, and if the system if operated at a fairly high rate to keep temperatures up. 

Here is another important point. Admitting tar into the engine does not necessarily destroy the engine (well, not all at once - it will certainly reduce its life). Rather, what tends to happen is a tarry glaze or varnish forms in the cylinder head that leads to sticking valves (although, bending an intake valve push rod is likely). Hence, in a remote off grid setting it's important to select an engine that is easy to disassemble for repairs if necessary. It's also a good idea to have two identical engines for redundancy. Using a FEMA type gasifier for fueling engines will require a regular maintenance schedule to keep the engines operating reliably. This might be worth the trouble since a FEMA gasifier is simpler to build, and it is less likely to bridge when small wood chips are used as fuel. However, I believe it's too easy to devise an Imbert system that would practically eliminate the problem. Also, a basic FEMA design can be modified relatively easily to improve results by essentially converting it to a basic Imbert design. This would entail adding a restriction at the base of the fire tube, insulating the fire tube, sealing the top of the hopper, and introducing air to the fire tube with nozzles. Preheating the air with the hot fuel gases is also a good idea.

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## buenijo

Video featuring Wayne Keith: http://www.youtube.com/watch?NR=1&v=...ture=endscreen.

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## buenijo

I've been looking into wood gasification a lot more lately. It's just too damn easy to build a gasifier to not consider this a primary means for an individual to achieve energy independence. Sure, I love steam engines. However, this option can't be practical until a good steam engine system becomes commercially available.

I am 100% certain that anyone can build a FEMA or an Imbert gasifier using the information available here http://www.woodgas.net/files/FEMA_em...y_gassifer.pdf and here http://alternativefuels1.tpub.com/0276/index.htm, and the parts available at www.mcmaster.com and/or the local hardware store. I encourage anyone who is interested to take the leap if you have suitable fuel readily available. At the very least you should come to understand the process so that you can put the technology to use in the future should conventional fuels become prohibitively expensive. At the very least it's interesting to consider. 

As far as the off grid setting goes, there is enormous benefit to using wood for fueling a work horse pickup truck. Personally, I would dual-fuel such a vehicle with gasoline to allow for a smaller gasifier system. This same gasifier could be used for battery charging an off grid solar system at the homestead should be need arise. 

Basically, I'm more bullish on wood gas engine systems now than ever before, and I highly recommend everyone look into it.

ADDENDUM: These systems are best used to provide back up power generation (such as battery charging) in the remote off grid setting. Photovoltaics should be the primary means of power generation since these consume no fuel, and because PV hardware is now affordable and reliable. A gasifier is also useful as a heat source without having to operate the engine.

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## buenijo

I've been looking into an idea to use solar thermal energy from concentrators to boost the production of fuel gases from a biomass gasifier. Basically, the idea involves using solar heat to drive pyrolysis rather than combusting part of the fuel mass to provide this heat. The main benefit is not increased efficiency, but a fuel gas undiluted by nitrogen in the air. Here is one article I came across that discusses the basics of this process http://biomassmagazine.com/articles/...-gasification/. There is also mention of using the gas generated to synthesize liquid hydrocarbons through Fischer-Tropsch (http://en.wikipedia.org/wiki/Fischer...ropsch_process). Also, there is mention of using algae as a biomass feed stock for the process which is an idea I find very appealing. Most research into using algae for biomass fuel are focusing on very specific strains of algae for their high oil production. There is often deleterious side effects with selecting organisms for specific traits. You might get the desirable trait expressed, but it generally comes at the expense of the general viability of the organism. Using gasification might allow for culturing and harvesting a more hardy (and natural) strain. Interesting.

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## buenijo

Just sharing some thoughts on converting an automobile to be dual-fueled with a wood gasifier (just trying to get people thinking on the topic). The advantage of "dual-fueling" is the ability to use a much smaller gasifier system than would be required to convert a vehicle to 100% wood gas. Since a vehicle engine normally operates at a small percentage of its rated power, a very small gasifier could reduce the consumption of liquid fuels a great deal. So, the gasifier would provide the bulk of the fuel while at low power like idling and maintaining speeds on level ground, but liquid fuels are retained for a power boost when required for acceleration and hill climbing. There are technical problems that I've considered, but I don't consider them too daunting. It seems this approach would be a simpler conversion than going for 100% wood gas.

NOTE: Here is a video of Wayne Keith driving his truck in "hybrid mode" (i.e. dual-fuel): https://www.youtube.com/watch?v=rJg_D5dBt-g . There seems little benefit in this case since his system can maintain highway speeds without gasoline, but it's a good video to illustrate that it works fine.

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## buenijo

deleted

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## The Northbreather

Awesome post! At the very least this is a gasoline/diesel free way to run your generator. Sometimes even in california you need to charge your  PV battery bank with your geni for a bit during those periods of low solar gain. Awesome.

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## buenijo

> Awesome post! At the very least this is a gasoline/diesel free way to run your generator. Sometimes even in california you need to charge your  PV battery bank with your geni for a bit during those periods of low solar gain. Awesome.


Most likely, I'll have to use gas engines since I doubt I'll find suitable Diesel engines for this purpose. While I like the idea of dual-fueling a small stationary Diesel with a gasifier, it is simpler to just use a gas engine. 

If you're interested in the technology, then make sure to read all the posts and check out the links that I provided. If you have any questions, then just post them here.

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## buenijo

CHARCOAL GASIFIERS!

I started looking into alternative energy again, and stumbled on an elegantly simple charcoal gasifier by Mr. Gary Gilmore. I provide links to his YouTube channel, additional YouTube videos that feature his unit, and a link to a forum dedicated to charcoal gasification. First, let me discuss charcoal gasification vs. wood gasification.

There's good and bad when it comes to charcoal gasification. Among the bad is that more than half the energy in wood is lost during the charcoaling process. I've considered a way to put the energy to use that might be done in a stationary setting. Charcoaling is essentially heating wood to drive off water and volatiles to leave the bare carbon and ash behind. These volatiles are combustible. Therefore, in principle, it is possible to combust these gases and put the heat to use. The heat could be used in the charcoaling process itself, and also used to heat a copper coil connected to an insulated vessel of water in a closed loop (this will heat the water in the vessel by thermosiphon) to provide hot water and space heating for the home. BTW, this thermosiphon approach is a very simple and effective way to heat a lot of water. Also, the hot exhaust gases can be used to heat a thermal mass like those used in rocket mass heaters. NOTE: I had researched charcoal gasifiers before, but I dismissed it because so much energy is lost in the charcoaling process. However, if one can make use of this energy, then perhaps these sins can be forgiven. 

In my opinion, among the best uses for a gasifier in an off grid setting is to fuel a small genset for battery charging to back up a solar array (when solar is insufficient as during inclimate weather) and for conditioning a battery system (like when equalizing cells periodically). If the system is properly designed, then one should rarely have a need for using charcoal for these purposes. However, one might have more need for heat (water heating, water processing, space heating). Therefore, it's possible (in principle) to devise a system where the volatiles from a regular charcoaling process can be used to provide this heat for the home with the charcoal stored for later use. It may even be possible to store up enough charcoal to displace a lot of gasoline/diesel in automotive use. NOTE: I don't like EV's, so please don't suck me into a debate on that.

The good news on charcoal gasification is that the gasifier is a helluvalot simpler than a unit required for wood, and it's a lot simpler to operate. If properly designed a small charcoal gasifier requires no dedicated cooling system, no condensing system, and a lot less filtration. Just my speculation here, but a small charcoal gasifier might be practical for dual-fueling a conventional compact car due to the simple nature of the system (perhaps a simple and compact unit could be mounted on the rear bumper, or placed in the trunk - lots of caution advised here!), and the fact that the energy density of charcoal is higher than wood (a pound of charcoal contains more energy than a pound of wood). Furthermore, being able to use a compact car vs. having to purchase a pickup truck (to fit all the systems required for a wood gasification system and carry the massive engine required to run on 100% wood) means that a pound of wood used to make charcoal and fuel a small charcoal gasifier for a compact car can take the driver as far or further than the same pound of wood used in a wood gas pickup. When the volatiles driven off during the charcoaling process are put to use in heating applications, then this approach comes out way ahead on an energy balance perspective.

Note one particularly interesting aspect to this process. Mr. Gilmore directs some of the exhaust from the engine back into the charcoal gasifier. The purpose of this is to moderate the extreme temperatures in the reactor. Introducing some CO2 in the engine exhaust back to the gasifier cools the unit by the endothermic reaction where CO2 combines with the carbon in the charcoal to produce more CO. Overall, it actually increases the efficiency of the system by converting heat to chemical energy thereby reducing the cooling load on the system (the temperature of the fuel gases leaving the gasifier actually goes down and the fuel gas quantity and quality goes up). In theory, it's also possible to use the heat from the system to generate steam that can be injected into the gasifier (pulled in with the intake air) which would both cool the gasifier and produce hydrogen gas. Producing H2 may increase engine performance markedly because it burns faster than CO, and this might make sense for automotive use to increase engine power at higher engine speeds. 

http://www.youtube.com/watch?v=yL79ci4TH7k

http://www.youtube.com/watch?v=EbI6r7hPmHA&feature=plcp

http://www.youtube.com/watch?v=srLETKDrwto

http://www.youtube.com/watch?v=1gmg_...ature=youtu.be

http://driveonwood.com/forums/charcoal-gasifiers

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## Lifesoup

Buenijo,
Good to see you posting again on ALT energy subjects...

The Gilmore is inspired by the popular and advanced, post war, kalle.  As far as I can tell, the kalle did not have the ability to use raw biomass so this is an advancement. The Kalle, however, was a more true fluidized bed because it purposely recirculated charcoal "fines" (dust) back into the reaction lobe.  Also the kalle had a dynamic vacuum operated inlet movement that would compensate for engine demand.

Below is a link to the system I am developing presently.  This is an overview of the system.  I took this vid in October.  Since then I have installed it on my wheel horse tractor.

http://s1336.beta.photobucket.com/us...tml?sort=3&o=1

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## buenijo

Hello! Good to see someone putting these theories to actual practice! We need advice from people like you who are advancing beyond research. Please provide more specifics about your reactor design including associated systems. How much welding was required if any? You are using charcoal, is this right? From what wood species is your charcoal derived, and how are you producing it? The kind of system I have considered would require a very efficient charcoaling method to be practical from an energy balance standpoint, so I'm real interested in any ideas you can provide on charcoaling. The Gilmore system interests me for its simplicity and functionality. I think there is a lot of potential for advancing its development, particularly with cogeneration to increase the overall efficiency, and steam admission for H2 production.

Consider that if you're using only charcoal in your reactor (not including biomass added periodically as you showed us), then you're getting very little H2 production. In fact, assuming the charcoal is pure, you're not getting any H2 beyond what might be generated from water vapor present in the inlet air. Therefore, the exhaust from your engine will contain very little water vapor (it should be mainly N2, CO2, some residual CO, very little H2O, and trace gases). So, recirculating the engine exhaust in that case will not increase H2 production. Have you considered steam injection? In principle, I think it's possible to devise a system that controls steam generation and injection rate as a function of reactor output that would naturally keep the temperature in the reactor moderated to within ideal parameters while also getting you lots of H2 production (the trick is finding the right heat source in the system to generate the steam, and sizing the heat exchanger properly). This should be simpler than adding biomass periodically, and you wouldn't have to worry about tars. NOTE: I believe CO is a fine engine fuel, and a slow moving stationary engine shouldn't bother with steam injection to make H2 (just recirculate engine exhaust to make a richer fuel gas - more CO). However, I've been wondering about a system for automotive use (possibly dual-fuel) that might benefit from steam injection. Either way, I hope you experiment with steam injection on your unit just to see how it performs! Please share with us the results. Thank you!

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## buenijo

Lifesoup, what do you think about charcaoling pine needles for use in your gasifier? The reason I ask is because these are ubiquitous where I'll be moving. If you have any curiosity about how it will work, then please try it out and let us know how it goes.

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## buenijo

Article on charcoaling by Gary Gilmore:

http://www.puffergas.com/historic/rules/rules.html

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## Lifesoup

buenijo,

I am using charcoal in a semi-fluidized bed.  It is various hardwood species made in a TLUD gasifier - very similar to Gary's "double barrel" method.  The heat generated during the charcoaling process will eventually be used for domestic space/water. I need to find the time to weld up some heat exchangers.

About the ICE exhaust....there is more H2O than you think. It is a major product of combustion.  I am usually maximizing the water vapor in the reaction.  Any more and it will not crack.  FWIW, I think a car puts out nearly a gallon of water for each gallon of gasoline combusted.

Right now i am working toward automating the EGR valve and auger feeding raw biomass.  Also, I will be monitoring and controlling the reduction lobe with a type k thermocouple signal to ensure that tar is not an issue.  Eventually, I'd like to use an oxygen sensor signal to control the air mixture into the ICE.
My goal will be to maximize the raw biomass feed and minimize charcoal usage.  We will see....

Kalle was very successful with his charcoal gasifiers in automotive applications.  Check into it.

If you're interested, here is a link to some more videos of my system running the wheel horse.

http://s1336.beta.photobucket.com/us...%20Experiments

I've come a ways and I have a ways to go.

Kind regards,

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## Lifesoup

> Lifesoup, what do you think about charcaoling pine needles for use in your gasifier? The reason I ask is because these are ubiquitous where I'll be moving. If you have any curiosity about how it will work, then please try it out and let us know how it goes.


I am curious for sure.  I would take bets that we could easily use dry pine needles as raw biomass. Hopefully, it would not cause too many clinkers.
I will try this and see how it goes.  As far as turning the needles to carbon....My problem right now is that daylight hours are few and my automation agenda must prevail.  I, for one, can't wait for 12-21-12 - then the count down becomes a count up

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## buenijo

> About the ICE exhaust....there is more H2O than you think. It is a major product of combustion.  I am usually maximizing the water vapor in the reaction.  Any more and it will not crack.  FWIW, I think a car puts out nearly a gallon of water for each gallon of gasoline combusted.


I understand, but in this particular case with raw carbon (i.e. charcoal) as the only fuel (assuming one is not supplementing with raw biomass), there is no source of water vapor beyond what water is retained in the charcoal and what water vapor may be introduced with the intake air. In the case of conventional automotive operation the combustion of the hydrocarbon fuel provides the H20. In the case of a charcoal gasifier, only carbon is available to combine with the free oxygen... hence, only CO fuel gas results.  Therefore, there is very little H2O available in the engine exhaust. Still, the CO2 in the engine exhaust will react with the carbon to moderate temperatures while also extending the useful life of the fuel (effectively converting heat energy to chemical energy). What I'm curious about is really bumping up hydrogen production in the fuel gas through steam injection. I think you might see a pronounced increase in engine performance.

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## buenijo

> I am curious for sure.  I would take bets that we could easily use dry pine needles as raw biomass. Hopefully, it would not cause too many clinkers.
> I will try this and see how it goes.  As far as turning the needles to carbon....My problem right now is that daylight hours are few and my automation agenda must prevail.  I, for one, can't wait for 12-21-12 - then the count down becomes a count up


I also think shredded pine needles would be an ideal biomass source to augment the charcoal. I've played with it before, and it goes through a small auger easily. Plus, (at least where I'm from) you can find suprisingly dry pine needles in large quantities on the forest floor. You might be able to just run the needles through a chipper/shredder, then straight to the hopper to let an auger feed the gasifier.

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## Lifesoup

There are quite a few historic examples of steam injection.  And no doubt, it is a proven method to increase hydrogen content.  If I were to go that route, I would probably draw inspiration from the Pedrick plate style for its sheer durability and simplicity.  But there are others too.

With the system I am developing, water is probably maximized.  It is coming from the raw biomass, charcoal water retention, atmosphere, and in turn, from the EGR.  I have actually had to design water control into the EGR line.  With this set-up, any more water and Boudouard's double arrow turns against me.  Both the CO2 and the water gas reaction are VERY endothermic.

I suppose you could incorporate some sort of induction coil or plasma arc to overcome the unbalanced endothermic side?  Something like flash super-heated steam, maybe?

My path is to maximize raw biomass and minimize charcoal.  This too gives energetic gas.  And I think some fairly simple (and cost effective) automation, thru programmable logic chip sets, will create a hands-off modern solution.

I would be very interested in cost effective ways to limit atmospheric nitrogen or to convert it, in part, to something combustible!

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## osan

> Lifesoup, what do you think about charcaoling pine needles for use in your gasifier? The reason I ask is because these are ubiquitous where I'll be moving. If you have any curiosity about how it will work, then please try it out and let us know how it goes.


Pine _anything_ creates a lot of creosote, the buildup of which leads to stack fires.  If you have never experienced one of those, I can tell you first hand that it is nothing you want to see or_ hear._  Stack fires sound like a damned jet engine, will burn through your flue in no time flat, and will take your building right along with it. 

That all said, I am not sure of the specific qualities of pine charcoal save to say that none of the many blacksmiths with whom I am familiar that use charcoal employ pine.

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## osan

I have been following this thread only loosely as the impetus to do so has been secondary to other avenues of musing.

I find the whole idea very interesting but I also raise a cautionary flag to those seeking to develop such systems.  The drive to maximize efficiency is well understood and taken by myself, but it must always be born in mind that as efficiency in such matters rises, most often so does complexity.  All this talk of EGRs and what have you illustrate these sorts of complexities. 

The reason I raise this point is two-fold.  Firstly, when we speak of being "off grid" the notion of maximal self-sufficiency is most often deeply ingrained in the discussion, however tacitly in many cases.  The more complex such systems become the more dependent one becomes on manufacturing techniques beyond the individual's capabilities.  This, of course, cannot be entirely avoided as materials such as steel are difficult to manufacture and process by lone individuals, but if "off grid" is to have a more serious meaning, I believe that maximal simplicity becomes a high virtue.

The other reason I sing the virtue of simplicity relates to the times in which we currently live.  In a sane and stable world where people live freely and are of such a disposition as to be intolerant of interpersonal trespass, whether by other individuals or mobs of them, the most common being the one calling itself "government", such added complications pose less of a potential problem to the individual making use of such sophisticated engineering.  Markets are free and where demand lies, someone somewhere will be endeavoring to meet it, most likely.  This largely ensures that those things which are important to us will be available and mostly plentiful.  The only real threat to us then posed are unavoidable shortages and natural or synthetic catastrophes of greatly significant magnitudes.  These are usually few, far between, and can be handled.

But in times such as these, where the threats posed by the ever growing power, avarice, and vicious insanity of governments in specific and of people in general, complexity can become an enemy because it usually degrades reliability.  Granted, reliability can be engineered to be rock-solid even in very complex systems (consider hard-disk drives and even automobiles), but when a failure in such well-built mechanisms occurs, the expense to correct is usually high and correction without the properly engineered replacement parts either impossible or will not provide equal reilability.

Two short examples.  We bought our current farm and in the well built house we placed brand new washer-dryer pair.  Very nice Westinghouse units that make my wife happy.  In under a year a control board went kerblooey in the dryer.  The unit was under warranty and so the manufacturer sent techs to replace the board and all has been peachy in the two years since.

Sometime after that, I smelled the acrid odor of plastic about to erupt into flame and discovered a control board on the water heater next to the washer-dryer had also gone crunch.  It was technically not under warranty any longer by perhaps 6 months, but GE was very good about it and FEDEXed me a new one, which I installed and was again well.

Now, consider my plights in a world where the economy has actually crashed, unlike today where is it hobbling along but is far from face-planted.  Where will the replacement parts for such computer-controlled machines issue?  Possibly nowhere, and tens of millions of units of this, a few hundreds of millions of that, and so forth down a very long list of common amenities will go dark, cold, and lifeless holding little to no hope of ever being revived.

Keep moving forward in your R&D by all means, but were I to be in your places I would design such that the absence of any or even all of the closed look feedback controls whose complexity renders them beyond the individual's capacity to reproduce should not render the unit inoperable.  Such units should be able to run at reduced efficiency in a "bare bones" mode.  I believe in engineering for eternity.  It is how I design mechanisms and houses and the like because I believe in the virtues of longevity and of frugality with the precious resources that so many around me appear to waste with nary a thought about it.

The common mindset as applied to military aircraft produced the F35.  Mine, the A-10. 

Let this be nothing more or less than a friendly reminder of the sort of thinking that should go into design of such devices.  Survivability is a good thing.

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## Lifesoup

> Keep moving forward in your R&D by all means, but were I to be in your places I would design such that the absence of any or even all of the closed look feedback controls whose complexity renders them beyond the individual's capacity to reproduce should not render the unit inoperable.  Such units should be able to run at reduced efficiency in a "bare bones" mode.  I believe in engineering for eternity.  It is how I design mechanisms and houses and the like because I believe in the virtues of longevity and of frugality with the precious resources that so many around me appear to waste with nary a thought about it.


Well said.  I agree with this and keep it in mind.  This also applies to developing a system that does not require constant user input and therefore frees you up for other tasks.  Now off to the shop I go!

Kind regards,

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## buenijo

Hi Osan. Thanks for chiming in, I'm always interested to hear your thoughts. I wondered myself why nobody charcoals pine wood. The only answers I were able to find include that pine has about 2/3 the energy of the same volume of many hard woods. This quality carries over to the charcoal. Also, pine charcoal breaks apart more easily, so it's particularly bad for transporting (as in, to a final sale - the end user is likely to end up with a large volume of charcoal dust). However, both pine and pine charcoal have about the same btu's per pound as their hard wood counterparts, its just fluffier and crumblier. A proper charcoaling process should drive out all the volatiles from pine, including those that cause creosote.

I concur with your statements on simplicity vs. efficiency. I admit that I fall into the trap on occasion when I consider possibilities. I do this more out of a desire to illustrate the underlying principles (i.e. the physics) involved with a process more than any other single factor. However, when I see something truly simple and functional, then I get real interested. The Gilmore Gasifier is the latest example. If the entire system required to support the technology can be as simple as the gasifier (i.e. fuel gathering, charcoaling, waste heat recovery, fuel storage, etc.), then it can be a big winner. I'm convinced it's possible to come up with a simple charcoaling procedure to produce fuel for the gasifier, yet also harvest a large amount of waste heat from the charcoaling process toward water heating and space heating, and do so in a system with no moving parts (although, a small fan or two would be useful). Also the exhaust gas recirculation line is no more complex than the line that connects the gasifier outlet to the engine. More important, it's necessary to cool the reaction and extend the life of the unit, but it also generates a richer gas. I believe even better results can be obtained with steam injection, and this can be done by placing a small copper tubing coil to be heated by the hot fuel gases leaving the gasifier. One end of the coil is connected to a small water vessel, and the other is connected to the gasifier air inlet. Like the exhaust gas recirculation, it should be self-regulating and requires no moving parts.

----------


## buenijo

> My path is to maximize raw biomass and minimize charcoal.  This too gives energetic gas.  And I think some fairly simple (and cost effective) automation, thru programmable logic chip sets, will create a hands-off modern solution.


I agree, as long as you're adding biomass, then adding steam would redundant. On that note, it seems that trickling in finely shredded pine needles with an auger might get you where you what to be. Sawdust too! I played with both of these in a small auger I built to feed a little camping stove, and I was amazed at how precisely I could control the feed rate. 

Please keep in touch with the forum. I think your work is fantastic! I saw all the videos you posted, and it makes me want one of your units, .

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## Lifesoup

buenijo,

You think better results with just steam than with raw biomass/EGR combination?

A drip on the inside of a nozzle plate box will create flash steam that is pulled in with the inlet air.

----------


## osan

> Hi Osan. Thanks for chiming in, I'm always interested to hear your thoughts. I wondered myself why nobody charcoals pine wood. The only answers I were able to find include that pine has about half the energy of the same volume of many hard woods. This quality carries over to the charcoal. Also, pine charcoal breaks apart more easily, so it's particularly bad for transporting (as in, to a final sale - the end user is likely to end up with a large volume of charcoal dust). However, both pine and pine charcoal have about the same btu's per pound as their hard wood counterparts, its just fluffier and crumblier. A proper charcoaling process should drive out all the volatiles from pine, including those that cause creosote.
> 
> I concur with your statements on simplicity vs. efficiency. I admit that I fall into the trap on occasion when I consider possibilities. I do this more out of a desire to illustrate the underlying principles (i.e. the physics) involved with a process more than any other single factor. However, when I see something truly simple and functional, then I get real interested. The Gilmore Gasifier is the latest example. If the entire system required to support the technology can be as simple as the gasifier (i.e. fuel gathering, charcoaling, waste heat recovery, fuel storage, etc.), then it can be a big winner. I'm convinced it's possible to come up with a simple charcoaling procedure to produce fuel for the gasifier, yet also harvest a large amount of waste heat from the charcoaling process toward water heating and space heating, and do so in a system with no moving parts (although, a small fan or two would be useful). Also the exhaust gas recirculation line is no more complex than the line that connects the gasifier outlet to the engine. More important, it's necessary to cool the reaction and extend the life of the unit, but it also generates a richer gas. I believe even better results can be obtained with steam injection, and this can be done by placing a small copper tubing coil to be heated by the hot fuel gases leaving the gasifier. One end of the coil is connected to a small water vessel, and the other is connected to the gasifier air inlet. Like the exhaust gas recirculation, it should be self-regulating and requires no moving parts.


Have any of you guys looked at the commercial gasification processes used with coal?

----------


## buenijo

> buenijo,
> 
> You think better results with just steam than with raw biomass/EGR combination?
> 
> A drip on the inside of a nozzle plate box will create flash steam that is pulled in with the inlet air.


It's been a while, but I recall (vaguely) the results of a charcoal fueled large truck that used steam injection. The amount of charcoal consumed per mile of travel was so low as to be fantastic. It was recorded during a formal test that included many different styles of gasifiers (done during WW2), and the charcoal consumption rate was about a third lower than the closest competitor. I'll have to research to find the source again. In short, the results were simply amazing. Of course, it wasn't attributed only to the gasifier as it probably had a lot to do with how the engine was optimized for that particular gasifier. I have to research the thermodynamics as I haven't looked into charcoal gasification in a long time. However, as it stands now I suspect that introducing fairly dry steam at a controlled rate will yield better results than raw biomass. Until I can verify the numbers, then consider it just a hunch.

ADDENDUM: I've been looking for some the old sources I studied, and I'm not having any luck. I think the simplest solution is to hook up a small pressure cooker on an adjustable range and inject the steam in the reactor just to see how it goes. I suspect that the thermodynamics are no better for either alternative. However, the one that achieves the highest hydrogen yield might result in better engine performance at higher rpms. I'll keep looking.

ADDENDUM: I'm at a serious disadvantage here by not having a unit lying around for testing and data acquisition. So, consider the following only the musings of a physics student. Perhaps the reactor can be super insulated which would greatly reduce heat losses. Of course, this would result in very high peak temperatures in the reactor. I propose steam injection to be used to moderate these temperatures. Furthermore, perhaps the sensible heat of the fuel gases leaving the reactor can be used to generate this steam. This configuration could be self-regulating. The kind of system I'm imagining would use a small reactor into which the charcoal is fed by an auger. A small unit should reduce the thermal mass of the unit (to allow equilibrium to be reached quickly). If the steam cools too much, then make the steam generator smaller and/or don't insulate the reactor so much. If the steam doesn't cool enough, then tap into the engine exhaust to make more steam. Again, I say inject steam and see what happens, take good data.

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## buenijo

Just making general comments on biomass gasification for the casual reader. Since the recent topic on this thread is charcoal gasification, I want to emphasize that a simple way to consider a wood gasifier is as a charcoal gasifier that charcoals the wood in situ (i.e. on demand). This is why the Imbert downdraft gasifier has been so successful on using wood fuel. In an obtuse way, it really is a charcoal gasifier. The problem with wood is that it's real hard to get the conditions in the gasifier just right under varying conditions. The solution during WW2 in the European countries that used a lot of wood fuel was to process the wood within tight specifications along with the gasifier design itself. The fuel was regularly sized wood cubes about 1-2" or so on a side, and dried to below 10% moisture. The nozzles in the Imbert gasifier are located just above a restriction in the hearth. Ash buildup around the restriction served to insulate that region from heat loss, and sometimes dedicated insulation for the hearth was provided in addition to this effect. It is extremely important for successful operation of a downdraft wood gasifier that peak temperatures in the restriction be very high. This means that the gas flow rate cannot be too low because the heat input rate will not be sufficient to overcome the heat losses, and low temperatures will result. This is why insulation is critical for low power operation or a wide turndown ratio (i.e. being able to operate over a wide power range - low to high).

So, the air enters the hearth at the nozzles to support combustion. On initial start up, the charcoal at the base of the unit is ignited while a blower fan supplies air to the nozzles. As temperature in the hearth region rises, the wood in the hopper just above the hearth will enter pyrolysis. This is fancy word that means the wood gets so hot that it gives of volatiles and water vapor (i.e. essentially the heat charcoals the wood). These pyrolysis gases given off by this process burn with the air provided at the nozzles. Unfortunately, wood has so many volatile compounds that it cannot all be combusted by this process. So, a properly designed wood gasifier must maintain temperatures high enough in the hearth so that any volatiles (i.e. tar vapors) that are not combusted will not pass through the restriction without cracking to simpler compounds that do not gum up the filter train or the engine. Again, insulation is extremely important. However, it's also important to size the fuel properly so that the tar vapors that exist in between the fuel particles are burned as much as possible and exposed to high temperatures. Otherwise, there may be regions in the fuel mass that are isolated from the reactions and essentially insulated from high temperatures. Under these conditions tar vapors can channel their way through the fuel mass and get past the restriction. It's a really tough dance because tar cracking is endothermic, so it tends to cool things down. It's very important to use dry wood. So, if everything goes well, then by the time the wood flows below the nozzles it will have been charcoaled. The products of the combustion of the tar vapors mentioned before include CO2 and H2O. However, CO and H2 are also produced. Hopefully, the vast majority of the tar vapors are burned or cracked after the gases pass through the restriction. Then, the combustion products CO2 and H2O can pass into the very hot charcoal to combine with the carbon and form more CO and H2. These reactions are also endothermic. 

Some systems like the Hot ToTTI at All Power Labs do a lot of heat regeneration to increase efficiency and allow for using wetter fuels. For example, their system uses the hot gases leaving the gasifier to heat the air before it enters the nozzles. The air can be brought up to over 1000F using this process. The heat remaining in the gases is used to preheat the wood fuel in a chamber to drive off water vapor (this water vapor is condensed out of the system). The now drier wood fuel is augered into a chamber that lies just above the main hopper. Here the exhaust gases from the engine is used to partially pyrolyse the wood fuel before it falls down into the hopper above the hearth. Jim Mason of All Power Labs notes that wood pyrolysis at relatively low temperatures produces tars that are more easily cracked. It's been pointed out that preheating air can increase tar production which seems counterintuitive. You see, increasing the temperature of the air admitted to the nozzles does not increase the supply of oxygen. All else equal it will increase temperatures. However, this higher temperature leads to a higher rate of pyrolysis. That is, the volatiles from the wood are driven off faster. With no additional oxygen available to burn these tar vapors, the only option available is for the higher temperatures to crack these additional tar molecules. So, the idea is that air preheating can increase the tar load all else equal. However, I believe this reasoning is flawed. Air preheating will add heat to the hearth region and increase the rate of pyrolysis AT FIRST. However, the process will lead to a new equilibrium condition where more charcoal is generated (i.e. the charcoal/wood line in the system rises). At this new equilibrium point the heat added to the system is retained in the charcoal and will enhance the ability for the charcoal to process the gases. Then there's the problem of bridging that occasionally pops up where the fuel doesn't flow regularly through the system. When it gets hung up the results can be temperature spikes as charcoal is consumed followed by a lot of tars that get past the hearth when the fuel mass dumps onto the hot charcoal once it's freed up. There is also the problem of not generally being able to operate a system at very low power levels. Under low gas loads, the heat loss at the hearth tends to lower temperatures which makes tar cracking difficult. However, high air preheating combined with excellent insulation (and dry fuel) is a good strategy for sustained low power operation.  

One of the reasons I am getting interested in charcoal gasifiers is because you just don't have to worry about the tar so much. This also means that fuel shape and size is not so important. Perhaps even more important is that you don't have to worry about building a gasifier with very particular hearth dimensions and nozzle diameters. You don't have to worry about a large filtration system. Now, I love the heat regeneration that APL is doing for its efficiency, but there's no reason why heat regeneration cannot be used with a charcoal gasifier. Air preheating is possible, and one can also send hot engine exhaust gases into the reactor. As mentioned in other posts, if the charcoaling is done in a stationary setting with most of the heat captured for useful purposes, then I'm thinking that charcoal gasification just might be preferable to wood gasification for fueling internal combustion engines. I really just said the same things in previous posts, but I'm trying to wrap up things in a tidy package for the reader.

More musings from the physics student here, but one of the several things I'm hoping may be possible for a charcoal gasification system is to charcoal fairly large pieces of wood to limit the fuel processing required. For example, perhaps wood can be split in 2-3" diameter sections that are 2-3 feet in length such that they can be packed in a retort for charcoaling. If this works out, then perhaps the charcoal can then be easily broken up into smaller pieces to serve as engine fuel. If this can be done along with capturing a lot of the energy for productive use during charcoaling, then it seems a lot better than a system based on a wood gasifier that requires carefully sizing the wood chips and chunks for the gasifier (especially if one desires a particularly low power system).

----------


## buenijo

> buenijo,
> 
> You think better results with just steam than with raw biomass/EGR combination?
> 
> A drip on the inside of a nozzle plate box will create flash steam that is pulled in with the inlet air.


Lifesoup, have you considered using waste heat from the system (such as engine exhaust and/or the hot fuel gases from the reactor) to heat biomass in a separate chamber, then pipe the pyrolysis gases to the reactor? Perhaps you can manage to charcoal biomass on demand with this system, then just transfer the charcoal into the reactor and replace biomass as required. Doing away with an auger and motor seems like a winner. The kind of system I'm thinking on here is similar to the APL unit, but with each stage well defined and separated to avoid fancy hearth configurations, augers, and motors. I'd have to crunch some numbers to figure out whether the system is self-sustaining on green biomass, but even if it's not it may mave merit. What I'm thinking is that that the water vapor from the in situ charcoaling could be pulled into the reactor to boost hydrogen and cool the reactor, then the volatiles would follow to do the same. Hopefully, by the time the biomass is fully charcoaled you will be left with the same amount of charcoal that was used at the start of the process. If so, then that's a good deal. Note the comment in the previous post where I state that Jim Mason of APL claims that tars generated at relatively low temperatures are more easily cracked. Perhaps this kind of process can support a wider range of temperatures in the reactor and still generate a clean gas. Also, let's not forget the potential for capturing the heat in the fuel gas outlet that might be used for air preheating. I know these sound complicated, but I'm game as long as there are no moving parts involved.

ADDENDUM: I seriously doubt the process can be self-sustaining. Even if the energy is there, it's another matter altogether in getting it where you need it. If the biomass is very dry, then maybe it can work to replenish the charcoal in a sustaining manner combined with recovering heat with air preheating. If one starts with green wood, then forget about it.

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## Lifesoup

> However, as it stands now I suspect that introducing fairly dry steam at a controlled rate will yield better results than raw biomass. Until I can verify the numbers, then consider it just a hunch.


For every CO2 the EGR brings there are 4 more N2 molecules that tag along. Maximizing raw biomass will minimizes the EGR but it will never completely eliminate the EGR.  It is needed to create headroom.  An effective tool to keep the reduction temp steady.

Of course this is not an issue _at all_ with the water gas reaction. Especially if you could easily meter the steam volume. So in that regard I see your point.

This brings me back to an earlier question: Any ideas on limiting or converting nitrogen into a combustible?  catalysts?  The gains that could come from this would be groundbreaking.

----------


## Lifesoup

> Lifesoup, have you considered using waste heat from the system (such as engine exhaust and/or the hot fuel gases from the reactor) to heat biomass in a separate chamber, then pipe the pyrolysis gases to the reactor? Perhaps you can manage to charcoal biomass on demand with this system, then just transfer the charcoal into the reactor and replace biomass as required. Doing away with an auger and motor seems like a winner. The kind of system I'm thinking on here is similar to the APL unit, but with each stage well defined and separated to avoid fancy hearth configurations, augers, and motors. I'd have to crunch some numbers to figure out whether the system is self-sustaining on green biomass, but even if it's not it may mave merit. What I'm thinking is that that the water vapor from the in situ charcoaling could be pulled into the reactor to boost hydrogen and cool the reactor, then the volatiles would follow to do the same. Hopefully, by the time the biomass is fully charcoaled you will be left with the same amount of charcoal that was used at the start of the process. If so, then that's a good deal. Note the comment in the previous post where I state that Jim Mason of APL claims that tars generated at relatively low temperatures are more easily cracked. Perhaps this kind of process can support a wider range of temperatures in the reactor and still generate a clean gas. Also, let's not forget the potential for capturing the heat in the fuel gas outlet that might be used for air preheating. I know these sound complicated, but I'm game as long as there are no moving parts involved.


Good timing to mention this!  You nailed it!

The engine exhaust was whispering this to me for quite a while.... Eventually I had to succumb.  I think there is promise here.  This chamber of engine pyrolysed wood _can go_ fluidized once the gasses are extracted.  The difficulty is in limiting condensation,in the line, back to the reactor.  Oh yeah, and those pesky N2 molecules are still crowding real estate.

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## Lifesoup

Just a quick tid-bit:

I found out fairly quickly that anything reactive-charcoal comes into physical contact with witnesses advanced degradation; even if your temps are in the zone.  This has to be accounted for when you are considering _feeding_ charcoal directly into the reaction area.  There needs to be a void between the most intense oxidation and the air inlet structure or you will (very) quickly exceed common material limits.  The wood gas guys allow for ash build up as insulation in critical areas, but ash build up in a char bed blocks reactive surfaces and causes rock hard clinkers.  A small void space is of great use.

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## Lifesoup

Charcoal is a very cool material.  It is highly reactive and highly insulating.

I can demonstrate this to people by holding a 2" piece of charcoal between my index and thumb.  I use a bic lighter to start it glowing right there between my fingers.  Then I blow on the lit spot while I have the observer hit it with my infrared thermometer.  The temp immediately goes off scale (1000 degrees F) while my fingers remain unaffected.  There is no smoke either; just heat waves.

A cool way to demonstrate the reactivity is like this:  I have the observer hold my propane torch (lit).  I then stand several feet away from them with an open top bucket of charcoal and give it a shake.  A few seconds pass and the torch starts lighting off a bunch of micro fire flies as the charcoal particles contact the flame.

Oh yeah, I almost forgot: gardens absolutely love the stuff!

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## buenijo

> Charcoal is a very cool material.  It is highly reactive and highly insulating.
> 
> I can demonstrate this to people by holding a 2" piece of charcoal between my index and thumb.  I use a bic lighter to start it glowing right there between my fingers.  Then I blow on the lit spot while I have the observer hit it with my infrared thermometer.  The temp immediately goes off scale (1000 degrees F) while my fingers remain unaffected.  There is no smoke either; just heat waves.
> 
> A cool way to demonstrate the reactivity is like this:  I have the observer hold my propane torch (lit).  I then stand several feet away from them with an open top bucket of charcoal and give it a shake.  A few seconds pass and the torch starts lighting off a bunch of micro fire flies as the charcoal particles contact the flame.
> 
> Oh yeah, I almost forgot: gardens absolutely love the stuff!


That's great stuff! Thanks for sharing. I've studied biomass gasification quite a bit in my spare time over the last couple of years, but I think I've now been bitten hard by the charcoal gasification bug. I've got ideas to keep me busy for a decade or longer, and I know more are coming. . My first hands on project will almost certainly be based in charcoal gasification with extensive heat regeneration.

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## buenijo

> Good timing to mention this!  You nailed it!
> 
> The engine exhaust was whispering this to me for quite a while.... Eventually I had to succumb.  I think there is promise here.  This chamber of engine pyrolysed wood _can go_ fluidized once the gasses are extracted.  The difficulty is in limiting condensation,in the line, back to the reactor.  Oh yeah, and those pesky N2 molecules are still crowding real estate.


Lifesoup, I added an addendum to the previous post. Basically, I suspect that if one starts with very dry wood, then it may be possible to use the heat from the engine exhaust to charcoal the wood at a rate sufficient to replace the batch of charcoal used to initiate the process IF there is enough heat regeneration in the system elsewhere. For example, the pyrolysis gases from the charcoaling process must be admitted to the reactor, and the air pulled into the reactor must be preheated as much as possible by the hot fuel gases leaving the reactor. Even better, some of the pyrolysis gases can be combusted in the feed tube to add heat to the reactor directly. Furthermore, the reactor must be highly insulated against thermal losses. Under these conditions is may even be possible to generate enough charcoal to store up for transport applications (I'm assuming the previous system is a stationary cogen system like a battery charging station - BTW, in that case all the heat cannot be transferred to the wood for charcoaling, so a system for water heating could be used to catch more wandering BTU's). 

For those reading, I know this sounds complex, and it is certainly work intensive to build, but when there are no moving parts involved, then I believe the "complexity" is justified if fuel consumption can be greatly reduced. It takes a lot of time and effort to design things right, but as long as the end result is made of readily available and inexpensive components with few or no moving parts, then it will be a winner.

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## buenijo

> Have any of you guys looked at the commercial gasification processes used with coal?


Hey Osan. Personally, I have not looked into commercial scale coal gasification.

----------


## buenijo

> For every CO2 the EGR brings there are 4 more N2 molecules that tag along. Maximizing raw biomass will minimizes the EGR but it will never completely eliminate the EGR.  It is needed to create headroom.  An effective tool to keep the reduction temp steady.
> 
> Of course this is not an issue _at all_ with the water gas reaction. Especially if you could easily meter the steam volume. So in that regard I see your point.
> 
> This brings me back to an earlier question: Any ideas on limiting or converting nitrogen into a combustible?  catalysts?  The gains that could come from this would be groundbreaking.


Sorry, I missed these questions. I haven't heard of any system to convert N2 to a combustible, at least not one that would be favorable from an energy balance perspective. N2 is very stable, so I doubt it's a good candidate here. The simplest nitrogen based combustible I can think of off hand is ammonia, but as far as I know it requires a H2 or CH4 feedstock with catalysts. What you're looking for is some way to convert more heat to fuel gas, but it seems to me that there is plenty of CO2 (or H2O) to take advantage of the high temperatures in the reactor. Beyond the reactor the only heat source is the engine exhaust, and temperatures are rather limited there. Please note that is all speculation as I have not done the research. Off hand, it seems to me that an ideal system would absolutely minimize thermal losses in the reactor, then use either CO2 recirc or steam injection to convert as much heat in the reactor as possible to fuel gases. Either approach could be self-regulating, but I speculate that steam might be preferable for enhancing engine performance. As far as the heat in the engine exhaust goes, well, drying biomass to prepare it for charcoaling seems like a good idea, and there's always heating applications in the stationary setting.

ADDENDUM: Just wondering that perhaps a cross-draft configuration would be preferable for your purposes. It seems this configuration would confine the heat to a smaller volume that can be more easily controlled to minimize thermal losses. Also, this would minimize thermal losses on shut down, it would reach equilibrium temps more quickly, and it should maintain a tighter control of reactor conditions during engine transients (i.e. less temperature variation during operation with tighter feedback control, depending on how the heat regeneration systems are configured).

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## Lifesoup

> Sorry, I missed these questions. I haven't heard of any system to convert N2 to a combustible, at least not one that would be favorable from an energy balance perspective. N2 is very stable, so I doubt it's a good candidate here. The simplest nitrogen based combustible I can think of off hand is ammonia, but as far as I know it requires a H2 or CH4 feedstock with catalysts. What you're looking for is some way to convert more heat to fuel gas, but it seems to me that there is plenty of CO2 (or H2O) to take advantage of the high temperatures in the reactor. Beyond the reactor the only heat source is the engine exhaust, and temperatures are rather limited there. Please note that is all speculation as I have not done the research. Off hand, it seems to me that an ideal system would absolutely minimize thermal losses in the reactor, then use either CO2 recirc or steam injection to convert as much heat in the reactor as possible to fuel gases. Either approach could be self-regulating, but I speculate that steam might be preferable for enhancing engine performance. As far as the heat in the engine exhaust goes, well, drying biomass to prepare it for charcoaling seems like a good idea, and there's always heating applications in the stationary setting.
> 
> ADDENDUM: Just wondering that perhaps a cross-draft configuration would be preferable for your purposes. It seems this configuration would confine the heat to a smaller volume that can be more easily controlled to minimize thermal losses. Also, this would minimize thermal losses on shut down, it would reach equilibrium temps more quickly, and it should maintain a tighter control of reactor conditions during engine transients (i.e. less temperature variation during operation with tighter feedback control, depending on how the heat regeneration systems are configured).


I agree N2 is a stable mess. It seems that by default it makes up 79% of the fuel gas.  Slightly more or less dependent on gasifier design.

Because of the inert nitrogen, plan on your internal combustion engine returning _at least_ a 30% power drop when operating on wood gas or hydrogen enriched charcoal gas.  The sheer volume of N2 crowds out and dilutes the combustible gasses.  This isn't a show stopper by any means, but it would be great to come up with ways to limit or convert N2.  Advancing the engine's ignition timing would help.  Even better if combined with an increase in cylinder compression.  Those mods, however, aren't really applicable on small engines.  On a non-modified gasoline engine the power drop is probably closer to 40% plus.

Yeah, I like the cross drafts.  I kinda like them all I guess.  I think my favorite right now, is the Gilmore/Kalle.  Air induction is preheated.  The open top allows easy introdution of supplemental fuel.  It does not need a grate....etc.

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## Lifesoup

Got some results from the weekend's woodgasser expirements..  This one is pretty simple.  Right now it is running on hardwood pellets.  It has no grate.  The flare looks really good and that is without any significant filtration (beyond the oversized cyclone), it will soon be time to fire the engine!

[IMG][/IMG]

[IMG][/IMG]

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## jmdrake

> I did a search of the forums here and was surprised to see virtually no mention of wood gasification technology. So, I'm providing an introduction to the technology. Those who have read my other posts know that I'm particularly interested in small scale steam power with biomass fuel and extensive waste heat recovery. However, if suitable biomass fuel is available, you don't mind the fuel processing required, and electrical power delivered at a high rate is the primary goal, then wood gasification might be ideal.
> 
> These videos provide a good demo:
> 
> http://www.youtube.com/watch?v=mnjDq...eature=related
> http://www.youtube.com/watch?v=FL7vj...eature=related
> 
> These videos provide more thorough explanation:
> 
> ...


Good info!  Unfortunately the "part 1 - 6" videos are all private.  

Mother Earth News had plans for turning an old water heater into a woodgas generator. 

http://www.motherearthnews.com/uploa...eratorORNL.pdf

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## buenijo

Lifesoup, you're having too much fun.

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## buenijo

Jmdrake, I deleted the videos and replaced it with a link to an excellent lecture on wood gasification by Jim Mason at All Power Labs.

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## buenijo

Lifesoup, I'm just thinking outloud here as I often do. I'm trying to imagine various configurations for charcoal gasifiers that can provide advantages. I was thinking on how a downdraft wood gasifier pyrolyses the wood near the hearth, then the air provided at the nozzles combusts most of these pyrolysis gases to sustain the high temperatures. The combustion products then pass to the hot charcoal where CO and H2 are produced. The problem with wood is that there are so many volatile compounds that it overwhelms the ability for the charcoal to handle the load. If all the pyrolysis gases were fully combusted, then there would not be sufficient charcoal available to generate a quality fuel gas. The result would be a weak gas and very high thermal losses. This effect is seen when one tries to drive a wood gasifier too hard. Admitting air at too high a rate increases combustion, but the fuel cannot be pyrolysed at an ever increasing rate proportional to demand. So, a higher proportion of pyrolysis gases get combusted, and the gasifier temps spike while fuel quality drops. Actually, tars are still likely to be carried through under these conditions because there's less time under high loads for complete combustion and tar cracking. Anyway, during normal operation the downdraft system has to manage to crack the remaining tars with high temperatures and/or catch them with a filter system. Is there another solution that is not necessarily more elegant or efficient, but simpler to operate, reliable, allows sustained low power operations, and produces a richer fuel gas? Perhaps heat from the system can be used to heat wood and provide pyrolysis gases to the charcoal reactor at a favorable rate, _and do so independent of the air supply_. Perhaps the pyrolysis gases can be fed through the base of the reactor and channeled through the hottest part of the reaction to crack the tars. A combination of feeding volatiles to the reactor at a lower rate, and the effect described by Jim Mason where tars generated by pyrolysis at lower temps are more easily cracked, may generate a clean fuel gas that is also a lot richer than traditional wood gas. 

Maybe it's possible to start the process with bone dry wood to provide the volatiles quickly while charcoaling the wood at the same rate that it's consumed in the reactor. I don't know, I'm just thinking out loud here.  

Synopsis: Basically, what I'm talking about is instead of burning pyrolysis gases and passing them through a hot charcoal base as is done in downdraft wood gasifiers to reduce combustion products to syngas, what about burning charcoal to generate CO and very high temperatures, then passing pyrolysis gases independently through the hot charcoal bed for cracking? Insulation to minimize thermal losses where appropriate and heat regeneration into the reactor (i.e. air preheating) should enhance results (assuming the idea is at all viable).

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## Lifesoup

buenijo,
Excuse my bias.  I'm going to give this conversation some reference points:
[IMG][/IMG]

In an effort to avoid misunderstanding.....
Lets call the darkest inner area the "oxidation lobe": indicated as 2
Lets call the slightly lighter area that surrounds the oxidation lobe the "reduction lobe"
Lets call the area near # 1 the gas "uptake annular"

If I understand you correctly, you would like to inject oxygen deficient, long chain, pyrolysis gasses into the oxygen depleted but highly reactive reduction lobe.  Is this correct?  Or, is it that you would simply like to add these gasses anywhere within the non-reactive zones and allow convection to do the rest?

I think I like where this is heading

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## buenijo

Lifesoup, well, my ideas here are definitely half-baked, so honestly I really don't know. What I was visualizing is a configuration that confines the reaction within a high temperature refractory at the base of a charcoal hopper, then admitting the pyrolysis gases in the bottom of this region (via a line that penetrates the base of the unit). In my visual, the air was admitted in the base as well with the air supply nozzle extending further into the fuel bed than the gas line. The purpose of the refractory was to try force the volatiles to move through the reduction lobe. The fuels gases would move through the charcoal hopper for filtering.

----------


## Lifesoup

buenijo,

Please notice, in the diagram, that the uptake annular is completely surrounded by the reduction lobe.  This ensures that all gasses, including vapor and pyrolysis gasses carried in convection currents, must pass through the reduction lobe.  A single thermocouple at or slightly above the uptake annular can monitor for the appropriate heat range of ~700 celsius.  Increasing or decreasing the amount of reduce-able supplemental fuel is a practical and reliable method of maintaining the optimal reduction lobe size.

That is one of the several reasons I advocate this configuration.

Charcoal is not going to be perfect carbon.  The intense heat of the 2 lobes will drive the remaining volitiles out for some distance outside of the reaction zones.  The ability to allow tars to pass must be eliminated by design.  This design is forgiving to less than perfect charcoal. I think it could be adapted to your proposal too. 

FWIW, trying to filter out anything more than the tiniest amount of tar is a loosing battle.  Cracking tar is the only way.  I like to make sure the fuel gas is tar free before any significant filtration is used.  The filtration is to remove particulates.

----------


## buenijo

I see what you mean. That's very clever. If you can feed particulate biomass at a highly controlled rate, then it seems your system is preferable to admitting pyrolysis gases. Can this system deliver tar free gas at very low engine power levels?

----------


## Lifesoup

> I see what you mean. That's very clever. If you can feed particulate biomass at a highly controlled rate, then it seems your system is preferable to admitting pyrolysis gases. Can this system deliver tar free gas at very low engine power levels?


The system outlined in the diagram came from the fertile mind of Torsten Kalle. It is quite clever and a very good foundation for modern refinement.

The diaphram at the top of the unit responds to engine demand allowing it to produce high quality gas over a large range - including low draw.  As the demand for fuel increases the pressure drop in the vessel causes the air nozzle to extend.  There is a corresponding growth in the two lobes when this happens, so even though the nozzle-to-uptake annular distance has increased, the reduction lobe still surrounds the annular.  Under low draw the nozzle and uptake annular are physically closer to each other so the smaller lobes still provide coverage.  Elegant.

----------


## buenijo

> The system outlined in the diagram came from the fertile mind of Torsten Kalle. It is quite clever and a very good foundation for modern refinement.
> 
> The diaphram at the top of the unit responds to engine demand allowing it to produce high quality gas over a large range - including low draw.  As the demand for fuel increases the pressure drop in the vessel causes the air nozzle to extend.  There is a corresponding growth in the two lobes when this happens, so even though the nozzle-to-uptake annular distance has increased, the reduction lobe still surrounds the annular.  Under low draw the nozzle and uptake annular are physically closer to each other so the smaller lobes still provide coverage.  Elegant.


It seems I missed this stop during my gasification travels. "Elegant" is right! I was thinking on adjusting nozzle length as a function of demand, but allowing the d/p to do it is just plain brilliant. I see how you got into this. In fact, I feel myself getting sucked into it too. In any case, I've got enough material to keep me from being bored for a while. 

If you have particularly good resources on the Kalle design, then please send them my way.

----------


## buenijo

I came across this discussion of the Kalle Gasifier: http://www.hotel.ymex.net/~s-20222/gengas/kg_eng.html. What a brilliant chain of reasoning.

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## Lifesoup

> I came across this discussion of the Kalle Gasifier: http://www.hotel.ymex.net/~s-20222/gengas/kg_eng.html. What a brilliant chain of reasoning.


The paper you just linked is a good one!
Unfortunately, it would appear that many of the specifics have been lost to time.  At least, the information is not readily available on the internet.  This is the case with quite a bit of the charcoal gas technology.  It's a shame really.  If you come across more please post it.

I have taken a "hands-on" approach to better understanding kalle's ideas

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## buenijo

> I have taken a "hands-on" approach to better understanding kalle's ideas


It's good you did. There's no substitute for experience! I'm speaking objectively here as my experience is so limited, but I have just enough experience to understand how little I know. I may be a university student, but I'm nothing like some of the young engineering students I've met. Some of those pinheads couldn't find their dicks without a mathematical model. I say empirical results are the way to go. Trial and error, testing, testing, and more testing! Anyway, this particular pic says a lot:

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## Lifesoup

I agree that empirical science is the way.  It is a balance of thoughtful analysis, resolute decision making, and doing. Design weaknesses become apparent then improvements ensue.

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## buenijo

Article on making charcoal: http://www.pssurvival.com/ps/charcoa...aking_2003.pdf

Video on making charcoal: http://www.youtube.com/watch?v=fBYaP5K0AkE

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## buenijo

Lifesoup, I watched your videos again on your charcoal unit. I'm real interested in what you're doing and how it progresses. Please keep us informed. In particular, I'm wondering about how far you've gone in replicating the Kalle design that is illustrated in the pic I attached to post #85. It seems you constructed a bellows actuator on your unit similar to that shown in the pic. Does it function in the same manner? Did you provide an adjustable screen/grate that moves as a function of engine output? If so, then how did you come to adjust the dimensions and spring constant to isolate the reduction zone? Did you measure the temperature at the screen/grate to do this? Sorry, I'm getting a little ahead, but I sure am curious about your project and how it comes along.

----------


## buenijo

Lifesoup, just sharing my speculations. I find myself fascinated with the prospect of extreme heat regeneration in a charcoal gasifier. Imagine using excellent insulation combined with regenerating as much heat as possible from the engine exhaust and hot fuel gases to accomplish air preheating and steam generation. It seems that such a configuration can be self-regulating (i.e. negative feedback) once it's properly designed (heat exchangers properly sized and positioned, and insulation in place). Adding steam would cool the reactor and should lower the temperature of the exiting fuel gases which would reduce the steam generation rate all else equal. Ideally, the heat added by preheating the air supply with engine exhaust can achieve an optimal balance where steam generated from the sensible heat of the exiting fuel gasses is pushed hard toward the water gas reaction. There would be no moving parts to these additions, and all one has to do is add water and charcoal. Furthermore, this configuration can regenerate more heat than any other scheme. Most of the heat in the exiting fuel gasses can be picked up by a compact copper steam generator coil in counterflow fashion, and the air preheater can be compact when heated by the engine exhaust because the mass flow rate of the engine exhaust is a lot higher than that of the air supplied to the reactor.

----------


## Lifesoup

> Lifesoup, I watched your videos again on your charcoal unit. I'm real interested in what you're doing and how it progresses. Please keep us informed. In particular, I'm wondering about how far you've gone in replicating the Kalle design that is illustrated in the pic I attached to post #85. It seems you constructed a bellows actuator on your unit similar to that shown in the pic. Does it function in the same manner? Did you provide an adjustable screen/grate that moves as a function of engine output? If so, then how did you come to adjust the dimensions and spring constant to isolate the reduction zone? Did you measure the temperature at the screen/grate to do this? Sorry, I'm getting a little ahead, but I sure am curious about your project and how it comes along.


Good observations. Yes I have constructed the diaphragm and yes the unit does have the capability of changing based on demand.  This unit, however, is my R&D test mule so its configuration is constantly evolving.  Kalle's approach was brilliant but his unit did not allow for easy introduction of raw biomass.  Mine does.  The path I am currently following, with this unit, is to maximize raw fuel, minimize charcoal usage and automate to the minimal level that will allow hands off operation.  I'm getting there.

Last night I ran the tractor on garbage plastic I had laying around.  That was satisfying.  I'll attach a pic of last night's flare....  It is what you are aiming for as far as color.

[IMG][/IMG]

The easiest way, I know of, to monitor (quantifiably) the appropriate temp and size of the reduction lobe is by installing a high-temp K type thermocouple just above the uptake annular.  If you are reducing there, you are good to go.  Of course, good observation of *reaction color*, gas quality, *flare color*, engine running state, etc., are also very beneficial and these things come with experience.

The spring rate isn't that difficult.  Just overcome the weight being held by a small margin.

In addition to the unit you see in those videos, I am developing 2 other configurations.  One is a raw wood gasser.  The other is a scaled down kalle inspired generator that I am hoping will power a motorized bicycle.

----------


## Lifesoup

> Lifesoup, just sharing my speculations. I find myself fascinated with the prospect of extreme heat regeneration in a charcoal gasifier. Imagine using excellent insulation combined with regenerating as much heat as possible from the engine exhaust and hot fuel gases to accomplish air preheating and steam generation. It seems that such a configuration can be self-regulating (i.e. negative feedback) once it's properly designed (heat exchangers properly sized and positioned, and insulation in place). Adding steam would cool the reactor and should lower the temperature of the exiting fuel gases which would reduce the steam generation rate all else equal. Ideally, the heat added by preheating the air supply with engine exhaust can achieve an optimal balance where steam generated from the sensible heat of the exiting fuel gasses is pushed hard toward the water gas reaction. There would be no moving parts to these additions, and all one has to do is add water and charcoal. Furthermore, this configuration can regenerate more heat than any other scheme. Most of the heat in the exiting fuel gasses can be picked up by a compact copper steam generator coil in counterflow fashion, and the air preheater can be compact when heated by the engine exhaust because the mass flow rate of the engine exhaust is a lot higher than that of the air supplied to the reactor.


My initial thoughts:
Using EGR to manage the reaction* is* self regulating since an ICE is essentially an air pump.  Engine induction and exhaust vary directly with each other in real time.  More intake demand = more oxygen into the reaction and more heat, but it also means more exhaust recirculation to balance the reaction.


To my way of thinking, steam injection is a much more challenging method of generating H2 and managing the reaction temp as precisely.  This is because most methods are not variable directly with engine demand and the water-gas reaction is VERY endothermic.  If you can find that sweet-spot of  self regulation, that would be great. I think it will be challenging.  Also, in some locations (like where I live) humidity can become a serious variable that will keep you on you toes as it changes day-to-day and seasonally.  

In my journeys, I have found it to be a design challenge to create a unit that keeps the fuel gasses dry enough to make the ICE happy.

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## buenijo

> My initial thoughts:
> Using EGR to manage the reaction* is* self regulating since an ICE is essentially an air pump.  Engine induction and exhaust vary directly with each other in real time.  More intake demand = more oxygen into the reaction and more heat, but it also means more exhaust recirculation to balance the reaction.
> 
> To my way of thinking, steam injection is a much more challenging method of generating H2 and managing the reaction temp as precisely.  This is because most methods are not variable directly with engine demand and the water-gas reaction is VERY endothermic.  If you can find that sweet-spot of  self regulation, that would be great. I think it will be challenging.  Also, in some locations (like where I live) humidity can become a serious variable that will keep you on you toes as it changes day-to-day and seasonally.  
> 
> In my journeys, I have found it to be a design challenge to create a unit that keeps the fuel gasses dry enough to make the ICE happy.


Yes, I understand the EGR is self-regulating. I'm just speculating on extreme heat regeneration and how using both water and air preheating to catch every possible wandering BTU might get impressive efficiency. However, whichever configuration proves most practical is the way to go.

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## Lifesoup

> Yes, I understand the EGR is self-regulating.


No doubt. I figure you understand this and much more.....
I was just setting the premise to compare based on some of the challenges I perceive with steam.  I am very much open to any suggestions as long as I can figure a way to pull it off.

My brother-in-law gave me a huge bag of (char) coal for Christmas
Awesome gift!

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## buenijo

> My brother-in-law gave me a huge bag of (char) coal for Christmas
> Awesome gift!


I got a good laugh out of this.  

It seems value truly is subjective as the "Austrians" argue.

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## buenijo

Lifesoup, I had started looking into charcoal gasification in lieu of wood gasification for the prospect of devising a compact gasifier to dual-fuel a small automobile. However, I am now considering a very low power battery charging system. In particular, supplementing with particulate biomass (such as shredded pine needles) combined with heat regeneration and insulation seems ideal under these conditions. Things get so much simpler when designed for constant output. I'm starting to appreciate the potential for supplementing a charcoal gasifier with biomass, especially since I'll be moving to a region where pine needles are ubiquitous (east Texas). 

I'm sharing speculations here yet again. I’m wondering if dropping particulate biomass directly into the oxidation zone of the reactor is desirable. It seems preferable to allow heat from the reactor and exiting fuel gases to first pyrolyse the biomass to allow preheated air to combust these pyrolysis gases, then send these combustion gases into the reactor along with excess air. What do you think? The idea here is that forcing oxygen to react first with these pyrolysis gases is the best way to extend the life of the charcoal. Adding biomass beyond a certain rate could make the introduction of tars likely. However, combusting the pyrolysis gases first should allow for adding biomass at the highest possible rate. This should add heat directly to the reactor with excess air maintaining the peak temperatures required for efficient reduction. 

What I'm visualizing is adding a grate of sorts to the end of the feed tube to contain the biomass long enough for pyrolysis, adding the nozzle tube to the end of the feed tube, then placing the screen over the nozzle tube and fuel gas tube (outer tube)... and also insulating the outer tube to encourage preheating of the incoming air. I'm also considering a stationary system with a fairly tall charcoal hopper and feed tube.

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## Lifesoup

I like your thoughts on designing for DC generation.  DC generation with a battery buffer would not require strictly consistent RPMs over varying loads.

As far as dropping in raw biomass: I think you have outlined a temperature and process gradient that naturally occurs as you drop raw biomass directly into the oxidation zone.

I drop an ounce or so of hardwood pellets into the oxidation zone at a time and observe the effect by looking down the induction pipe.  I can see that the immediate area the pellets fall into cools.  The pellets begin to pyrolyse within seconds and then they begin to convert to reactive charcoal as the temp comes back up.  All the while the reduction lobe is monitored at the uptake annular to eliminate the possibility of tar production.  It is easily intuitive.  I'm not sure how physical separation points would make any significant gain and it would add some degree of design/build difficulty.

In this arrangement, we are approaching a hybrid operating mode that brings the charcoal reactor closer to a wood gas generator.  It makes its own charcoal.

As with a wood gas generator, I can see a benefit to preheating and drying the raw fuel before it enters the oxidation zone.  With charcoal, this would help us standardize the feed rate by eliminating some (variable) water thereby conserving some charcoal BTUs.  Pre-heating with heat capture from the gas uptake side (wondering BTUs) seems like the way to go.

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## buenijo

> I like your thoughts on designing for DC generation.  DC generation with a battery buffer would not require strictly consistent RPMs over varying loads.


I'm glad you agree. There are so many reasons why this is preferable for off grid. The ideal off grid power system would minimize the battery system while also protecting it from excessive discharge at all times. The battery really is the Achilles heel of off grid power systems. I like the idea of using DC wherever possible, and use inverters for AC only where necessary. We went AC for the benefits of using transformers in transmitting power, and this doesn't apply in the off grid setting. The holy grail of off grid power systems in my mind (w/o violating physical laws and able to be constructed with existing technologies) is a super durable small engine that operates at extremely low speeds, low power, quiet, biomass fueled, high thermal efficiency, with good waste heat recovery, and operated at long intervals. A modern steam engine could be ideal (what a shame we don't have them). However, perhaps the system you're developing can work well with existing engines. I've considered modifying existing small engines by fitting them with heavy flywheels and optimizing the spark and timing for very low speed operation on wood gas to get efficient operation at low outputs for battery charging. Getting a modest battery to LAST is the goal... serious money saving potential here. 




> As far as dropping in raw biomass: I think you have outlined a temperature and process gradient that naturally occurs as you drop raw biomass directly into the oxidation zone.
> 
> I drop an ounce or so of hardwood pellets into the oxidation zone at a time and observe the effect by looking down the induction pipe.  I can see that the immediate area the pellets fall into cools.  The pellets begin to pyrolyse within seconds and then they begin to convert to reactive charcoal as the temp comes back up.  All the while the reduction lobe is monitored at the uptake annular to eliminate the possibility of tar production.  It is easily intuitive.  I'm not sure how physical separation points would make any significant gain and it would add some degree of design/build difficulty.
> 
> In this arrangement, we are approaching a hybrid operating mode that brings the charcoal reactor closer to a wood gas generator.  It makes its own charcoal.
> 
> As with a wood gas generator, I can see a benefit to preheating and drying the raw fuel before it enters the oxidation zone.  With charcoal, this would help us standardize the feed rate by eliminating some (variable) water thereby conserving some charcoal BTUs.  Pre-heating with heat capture from the gas uptake side (wondering BTUs) seems like the way to go.


I see your system as sorta redesigning the biomass with lower free water and chemically bound water (i.e. volatiles) to make an ideal fuel for a gasifier, along with sharply separating the zones for more control. I like it because it seems it will work for very low power operation, which interests me for the reasons listed above. The ideal biomass fuel for gasification would be dry, and it would contain about 20% fewer volatiles (see figure 3.5b of Handbook of Biomass Downdraft Gasifier Engine Systems, http://taylor.ifas.ufl.edu/documents...ne_Systems.pdf , page 18). It seems the goal is to make your charcoal last as long as possible before replenishment is required. It still seems likely to me that pyrolysing the biomass before it falls into the oxidation zone can help (speculation, of course). Perhaps adding a grate above the oxidation zone will work.  Pyrolysis gases generated at lower temperatures are reported by Jim Mason of APL to crack more easily. So, perhaps those generated by this process and not combusted will be more easily cracked, and perhaps this can be part of the means to maximize the introduction of biomass to the system. NOTE: I know I'm splitting hairs here, but I'm really interested in getting the initial charge of charcoal to last as long as possible.

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## buenijo

Lifesoup, BTW I had tunnel vision earlier by not considering the benefits of adding biomass incrementally to the reactor. I never doubted that it would extend the run time more than other options, but I was afraid of the tars and the added complexity. I now see the potential clearly... even in the automotive setting. In that case using quality wood pellets makes sense. Many don't realize how little volume good hard wood pellets take up. A suprisingly small storage tank of pellets could take a car a good distance, and a dual-fuel configuration could make for a particularly compact system. Lots of ideas already.

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## buenijo

I did a bit of research on pine needles. I referenced two studies that I'll link later. I found that pine needles are on average more than 9000 btu/lbm on a dry basis. This about 5% higher than the best hard woods. The ash content is about 3%. Anything under 5% does not normally present any problem with slagging. Finally, the bulk density of shredded pine needles is on the order of 10 lbs per cubic foot. 

Me thinks pine needles might be a good candidate for gasification. I am aware of one operating gasifier that is optimized for pine needles. However, I have no details on the system. It seems shredded pine needles added to a charcoal gasifier would work well.

"Heat of Combustion of Various Southern Pine Materials"
http://www.srs.fs.usda.gov/pubs/ja/ja_howard001.pdf

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## buenijo

Just sharing a wild idea. I was checking out some chipper/shredders powered by gas engines. Here is one example: http://www.amazon.com/Patriot-Produc...ot+chipper+6.5 . I saw the results of chipping branches with this particular product and the size of the chips are ideal for a small gasifier. Anyway, notice the shaft protruding from the flanged bearing at the center of the chipper rotor housing. Imagine coupling a small pulley or sprocket to this shaft to allow the system to operate an alternator for battery charging. What I am visualizing is being able to roll the unit to a battery charging station that allows the chipper to be secured relative to a stationary alternator. Once the belt or chain is connected, then the engine can drive the alternator. I considered this primarily because I like the idea of powering a stationary engine at very low speeds to extend the life of the engine and to reduce the noise. However, you need a heavy flywheel to operate these small single cylinder engines at low speeds. Well, in this case the chipper rotor provides the flywheel. If the alternator is driven by the engine at the proper gear ratio, then the countertorque presented by the alternator will prevent the engine from exceeding the desired low speed. The governor of the engine should keep the throttle fully open during operation for higher engine efficiency, and the lower speed of the engine is better for the lower burn speed of wood gas. I don't think the timing of these small engines can be changed, but operating the engine at a low speed effectively advances the timing so it should work well on wood gas.

When it comes time to produce fuel for the gasifier, just disconnect the chipper and roll it out to the work site and start chipping. I suppose one could run the chipper off the gasifier with a long hose, but chipping with gasoline fuel would provide more power and would also clean off any tar deposits that might have accumulated while running on wood. So, there is a good argument for running on gasoline occasionally in this setting. It seems reasonable since the gasoline fuel used relative to wood would be miniscule.

Also, while I'm throwing out wild ideas, I see no reason why the exhaust from a stationary engine cannot be used to heat a thermal mass such as used in a rocket mass heater configuration. Basically, this entails imbedding a lot of ductwork inside a thermal mass to heat it up. The rocket mass heater burns wood for just a few hours each day with most of the heat stored in the thermal mass. By all accounts it is extremely effective. So, throw in some ducting for engine exhaust.

Video of rocket mass heater: http://www.youtube.com/watch?v=4usXIAoy9us

NOTE: Capturing the heat from a batch charcoaling process with this kind of thermal mass seems ideal.

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## buenijo

I'm wondering about a charcoal gasifier used to power a low power battery charging system, and optimized for a steady state. It seems to me that the temperature of the fuel gases leaving the gasifier might be used as a control for an auger motor that feeds particulate biomass into the system. Cartridge style adjustable thermostats in this temperature range are very affordable, and so are small ac gear motors. Basically, the thermostat is a normally open switch that prevents the auger motor from operating. However, in high fuel gas temperature (setpoint determined by experimentation) the thermostat switch will close to start the auger motor and feed biomass into the charcoal reactor. This in turn will cool the fuel gases to below the setpoint. Choosing a motor and auger that operates at an ideal speed will minimize cycling.

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## Lifesoup

> I'm wondering about a charcoal gasifier used to power a low power battery charging system, and optimized for a steady state. It seems to me that the temperature of the fuel gases leaving the gasifier might be used as a control for an auger motor that feeds particulate biomass into the system. Cartridge style adjustable thermostats in this temperature range are very affordable, and so are small ac gear motors. Basically, the thermostat is a normally open switch that prevents the auger motor from operating. However, in high fuel gas temperature (setpoint determined by experimentation) the thermostat switch will close to start the auger motor and feed biomass into the charcoal reactor. This in turn will cool the fuel gases to below the setpoint. Choosing a motor and auger that operates at an ideal speed will minimize cycling.


The char itself does and amazing job of keeping the gas cool.  The exit gasses follow a very slow and linear heat-up as the charcoal bed is depleted.  It is a good way to determine when the char bed needs to be topped off.

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## torchbearer

wood gas = methyl alcohol?

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## buenijo

> wood gas = methyl alcohol?


Hi Torchbearer. The short answer is no, but there may be some methanol present.

The term "wood gas" refers loosely to the gases generated through wood gasification. The primary combustible products include carbon monoxide (CO), hydrogen (H2), various volatile organic compounds ("tar" vapors), and methane (CH4). A gasifier designed for fueling internal combustion engines will see very few tar vapors. CO and H2 are the dominant fuel gases present.

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## Lifesoup

> wood gas = methyl alcohol?


I would think that methyl alcohol could be recovered from the charcoal making process.....

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## buenijo

> The char itself does and amazing job of keeping the gas cool.  The exit gasses follow a very slow and linear heat-up as the charcoal bed is depleted.  It is a good way to determine when the char bed needs to be topped off.


Hi Lifesoup. Yes, I noticed how sending the hot fuel gases through the fuel mass cools the gases well. Of course, when the fuel runs low this thermal mass is no longer present, and the fuel gases get really hot. I noted how Gary Gilmore uses the rising gas temperatures as an indication that it's time to add charcoal (and NOT melt the hose!). My problem with this configuration is that it's not a steady state system, and therefore it will impair a control system during operation. I'm considering a highly insulated fuel gas delivery tube (the outer tube that surrounds the inner air supply tube). This should stabilize the temperature of the outgoing fuel gases quickly after start up. Under these conditions it seems the fuel gas temperature should be proportional to the temperature in the reactor. If so, then it can be used as a proxy for a control system.

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## buenijo

> I would think that methyl alcohol could be recovered from the charcoal making process.....


Actually, I'm quite sure this can be done. In fact, Tom Reed did a lot of work on this during the 1970's. Although, I believe it is mostly formed from the CO and H2 components of wood gas.

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## Lifesoup

Interesting article on making a small 12 VDC engine generator.  Gotta love those Honda engines...

https://homepower.com/sites/default/...tras/mark8.pdf

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## Lifesoup

> I'm considering a highly insulated fuel gas delivery tube (the outer tube that surrounds the inner air supply tube). This should stabilize the temperature of the outgoing fuel gases quickly after start up.


What kind of materials do you have in mind?

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## buenijo

> What kind of materials do you have in mind?


Whatever works, . This would be a trial and error game. I wouldn't try to insulate anything near the reactor because that's just asking for trouble. I'm interested in a stationary system, so a rather tall hopper with a corresponding long tube should stabilize the temperature well (and provide some air preheating). Also, I'm interested only in a steady state system. Under those conditions I think using the fuel gas temperature can work rather well.

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## buenijo

> Interesting article on making a small 12 VDC engine generator.  Gotta love those Honda engines...
> 
> https://homepower.com/sites/default/...tras/mark8.pdf


Check out this beefy 3 phase permanent magnet alternator: http://www.windynation.com/products/...net-alternator (1000 watts DC at 680 rpm, 24 volts). I've had my eye on this used with their 80 amp 3 phase bridge rectifier: http://www.windynation.com/products/...idge-rectifier .

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## Lifesoup

> Whatever works, . This would be a trial and error game. I wouldn't try to insulate anything near the reactor because that's just asking for trouble. I'm interested in a stationary system, so a rather tall hopper with a corresponding long tube should stabilize the temperature well. Also, I'm interested only in a steady state system. Under those conditions I think using the fuel gas temperature can work rather well.


Have you considered a repeat cycle timer versus the thermostat/snap switch solution?  Thoughts?

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## buenijo

> Have you considered a repeat cycle timer versus the thermostat/snap switch solution?  Thoughts?


Actually, yes. I've also considered just using an auger motor that operates continually at an ideal rate. However, I'm concerned about whether or not the auger will deliver fuel at a reliable rate. Also, a thermostat should make the system easier to deal with a wide variety of fuel sources. Of course, whatever works is the way to go. Yet, it does seem that a simple thermostat combined with using an auger motor that operates at the slowest acceptable speed would achieve the tightest feedback while still allowing for a rather simple system. Perhaps a variable speed motor would be useful for use with the widest range of fuel sources (from fluffy shredded pine needles to dense hard wood pellets), but then again maybe adjusting thermostat setpoint with different fuel sources can be a solution... and maybe more dense fuels will see a slower rate of pyrolysis that would be self-regulating. Testing is required.

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## Lifesoup

> Testing is required.


I'll see how tightly I can track that temperature.

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## Lifesoup

> I did a bit of research on pine needles. I referenced two studies that I'll link later. I found that pine needles are on average more than 9000 btu/lbm on a dry basis. This about 5% higher than the best hard woods. The ash content is about 3%. Anything under 5% does not normally present any problem with slagging. Finally, the bulk density of shredded pine needles is on the order of 10 lbs per cubic foot. 
> 
> Me thinks pine needles might be a good candidate for gasification. I am aware of one operating gasifier that is optimized for pine needles. However, I have no details on the system. It seems shredded pine needles added to a charcoal gasifier would work well.


Promising!

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## buenijo

> I'll see how tightly I can track that temperature.


Cool.

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## buenijo

https://homepower.com/sites/default/...tras/mark8.pdf

Holy crap, 13,000 hours on that little Honda? That's almost unbelievable. I would not have expected more than 5000 hours even under optimal conditions for such a small engine. In fact, for my use I was expecting to have to replace the engine every 2-3 years or so by running the engine every day for 3-5 hours. 13,000 hours is 9 years! Awesome. Yep, you gotta love those Honda engines.

Anything you can suggest on increasing the life of small engines will be very interesting and greatly appreciated. It seems the most important single variable is clear: pick the right engine. Operating the engine at a low speed and at a constant output is also ideal for clear reasons. I have also considered adding an auxiliary oil filtration system, and running synthetic oil... and being very careful about maintaining proper oil level in the engine. Any other suggestions?

Damn, I'm still stoked about the 13,000 hours.

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## Lifesoup

> Anything you can suggest on increasing the life of small engines will be very interesting and greatly appreciated.


Cast iron Kohler engines are great too.

As to engine life extension:

Don't let them lug. It amplifies internal stresses.

Don't overheat them, but run them long enough to get up to temp and burn off condensates in the oil.

If you really want to improve things, improve the oil capacity and filtration. Some of the oil by-pass filtration set-ups actually boast analytically cleaner oil after use than when it was new in the bottle.

Clean the intake air well.

With these gas producers, it is paramount that the gas is free of any dust of an abrasive nature. This needs to be a design consideration. A charcoal producer running too hot or with too high of a specific gasification rate, will make hard abrasive dust (fused ash). Soft charcoal will amplify this. Check the ash/dust for water solubility to be sure. The bad stuff is like sand - it will not dissolve.

Dry the gas to eliminate as many of the corrosives as possible. If you route the gas through the carb, make sure the butterflies aren't aluminum. As a matter of fact keep aluminum out of the filter train too. When it corrodes and gives way it will be heading for the engine.

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## buenijo

> Don't let them lug. It amplifies internal stresses.
> 
> Don't overheat them, but run them long enough to get up to temp and burn off condensates in the oil.
> 
> If you really want to improve things, improve the oil capacity and filtration. Some of the oil by-pass filtration set-ups actually boast analytically cleaner oil after use than when it was new in the bottle.
> 
> Dry the gas to eliminate as many of the corrosives as possible.


About how low an RPM can these single cylinders go? The reason why I considered the idea of using the engine on a chipper to drive an alternator is because the rather massive chipper rotor is directly coupled to the shaft. I don't know if it would be worthwhile to take the engine speed to 1200 (or lower), but that's what I was considering. There is certainly an ideal speed that optimizes efficiency. I would just determine it by testing. However, the heavy flywheel would allow me to test below an otherwise lugging speed. I'll need a chipper/shredder anyway, so why not?

I considered an auxiliary oil filtration system, but I can't find anything small enough for this kind of use. I suppose I'll have to rig something when the time comes. Is synthetic oil in this application worthwhile?

I had also considered pulling the fuel gases through a desiccant. Hell, charcoal might work well and followed by some really good particulate filters.

It seems overheating on producer gas is unlikely... or am I wrong? The prospect of taking a very small engine 10,000 hours has got me really interested. I hope a gasifier can work well here at such low outputs. I'm hoping for 1 hp continuous, so you can see how wood gasifiers had me rather frustrated.

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## buenijo

I discuss a rather wacky idea in another thread on this forum (the steam engine discussion). Basically, I'm considering an approach to charring wood on demand in a controlled process to generate steam for heating applications. I wonder, perhaps thinking along these lines can help to devise a reliable low power wood gas engine system. I see dealing with excess volatiles as the primary challenge that wood gasifiers have to face (well, assuming dry wood). So, perhaps a wood gasifier could burn off a portion of the volatiles to heat the system externally. Perhaps engine exhaust and extreme insulation can be used for the same purpose (as I mentioned elsewhere). I'm wondering what kind of configuration is ideal. I have considered a fairly compact charcoal gasifier with the Kalle-type tube extending down into the mass of fuel and to the bottom of the vessel. The tube is long to get good preheating of the air (however, perhaps a cross draft design is appropriate for a small unit to prevent bridging - the air could be heated by the fuel gases with another heat exchanger). There is a highly insulated shroud around the vessel. Engine exhaust gases are sent directly into the base of this shroud. Now, I considered that there would not be any heat transfer to the reactor directly. In fact, I expect the base of the vessel to be at a higher temperature than the engine exhaust. However, preheating the air sent to the reactor will compensate (actually, perhaps cooling the base of the vessel with engine exhaust will make it last longer, and there will likely be ash and char that insulates the inner wall of the vessel well to minimize or prevent any drop in peak reactor temperature). 

ADDENDUM: More musings (I'm bored). I'm curious about the potential for engine exhaust heat in pyrolysing dry particulate biomass that is augered into a charcoal reactor. How far into the charring process could this take things? Could most of the steam and pyrolysis gases be pulled in with the air intake? Would this be desirable? The way I see it, the potential is there. After all, this is basically what the Imbert does. Except, in this case, the heat that drives pyrolysis is not taken from the reactor itself. All else equal, this should help to maintain higher reactor temperatures to crack whatever tar gases are not combusted and carried into the reactor with the wood chips. What I'm suggesting is forcing dry particulate biomass into a Gilmore gasifier not into the air inlet, but into the charcoal hopper itself to replenish the charcoal (it seems this may be necessary to maintain the geometry of the system - the shape of the reduction lobe - as I can't see how feeding the biomass with the air supply can replenish charcoal to this region). The biomass is sent through a long tube that is aggressively heated with engine exhaust. A small tube is connected to the air inlet in hope of pulling in come pyrolysis gases that can be combusted to raise reactor temperatures and just plain get rid of some of the tars. Perhaps adding heat to the reactor in this manner and burning off some tars will allow any volatiles carried into the system with the fuel to be cracked in the reduction zone as the convection currents carry them through the system. Seems like a lot of trouble to have an auger and heat exchange system, but if it can produce a clean gas from particulate biomass at extremely low flow, then I say it's worth it. I suggest using the temperature of the engine exhaust leaving the biomass heater as a control for the auger motor. Of course, I'm considering a steady state system (low constant output). Also, why not send the engine exhaust across this biomass auger feed tube and into the biomass hopper? Might at well dry the fuel well before it gets forced through the feed tube by the auger, and this can only increase pyrolysis.

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## buenijo

I take the position that a wood gas engine system can be a viable system for powering an off grid home. However, if solar insolation is good, then photovoltaics should be the primary means of generating electricity. A wood gas engine system should be limited to backup power generation during periods of inclement weather when solar flux is low, and used for heating applications (which would be particularly useful in a cold climate during winter). However, if a region sees low solar insolation and has plenty of wood fuel, then I think it can be a practical system for primary power generation. The following discussion assumes this configuration. Note that while the charcoal systems are very interesting, I'm convinced that having to generate charcoal is unacceptable . Therefore, I'm focusing only on wood gasification. 

The problems associated with operating wood gas engine systems at low power levels can be solved with thermal masses and batteries. Since a wood gas engine system cannot operate reliably at low power levels (at least not without extensive fuel processing and careful design), then the most practical system would have to use a fairly large engine and gasifier used to bulk charge a large industrial battery at a high rate. Heat exchangers can be placed to pick up heat from the system using water (and storing hot water in an insulated storage tank). The basic idea here is to bulk charge the battery intermittently while harvesting heat, then tap these energy stores when the system is not running. One might put high power electrical loads on line while the system is charging (opportunity loading). In this manner the system may have to be charged only about 2-3 times weekly (of course, depending on the system requirements). When I write "bulk charging" I mean purposefully not achieving a full charge. An industrial lead acid battery does not require a full charge more often than about once a month (I emphasize "industrial" lead acid battery here). Since charging these batteries beyond the bulk stage is very inefficient and stressful on the battery, then I have come to believe strongly that it should be minimized. However, it MUST be done on a regular basis, and at least monthly, and I also suggest doing a short equalization at this time as well. These industrial lead acid batteries are rated for 1500-2000 full cycles, and in this setting the units will conservatively last 10 years if properly maintained (including adding water, keeping proper battery temperatures, not undercharging/overcharging, and getting that full charge on a regular basis, and periodic equalization of cells). A suitable battery purchased new would cost about $130-150 per rated KWh of storage capacity (assuming a forklift battery). 20-30 KWh capacity is about the right size for a modest off grid home operated in this manner, so expect to pay at least $3000 for the battery. While expensive, it's not so bad if it lasts ten years. The complete system would be bulky and heavy, and I see no way around this. 

Google "Ken Boak lister powercubes" for a description of his combined heat a power system based on a wood gas engine system. While not configured quite like this, it is very close.

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## buenijo

http://northernselfreliance.com/biomass/woodgas/

A very small gasifier has been developed over the last 5 years by mechanical engineer Stephen Abbadessa. It seems very promising by all accounts. It is called the "Victoria", and it will be offered for sale very soon. Designed to run on small wood chips, it can power small engines efficiently at outputs lower than most gasifiers.

ADDENDUM: The smallest of the gasifiers called "Anastasia" was recently tested by Engineer775 (of YouTube) with excellent results. No videos available, but anyone who watches his YouTube channel knows that a thumbs up from Engineer775 is solid endorsement.

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## buenijo

http://wiki.gekgasifier.com/w/page/3...esel%20engines

A single cylinder Lister type Diesel engine is converted to 100% wood gas without modifying compression ratio. Turns out the stock 17:1 compression ratio works well with 100% wood gas. The only modification required was removing the stock injector and replacing it with a long reach spark plug. According to the account the spark plug was easy to install. Next, an after market ignition system was installed with a sensor placed on the engine block and flywheel to control timing. The engine/generator system was originally rated at 2500 watts electrical and delivered 2750 watts electrical on wood gas. 

So, 17:1 is not a problem with wood gas... maybe even higher? If so, then perhaps testing some Diesel generators with a dual-fuel configuration with wood gas admitted to the intake manifold might not be so unreasonable.

NOTE: Currently, All Power Labs is experimenting with placing the spark plug in a different location on the Indian Lister type diesel that allows for retaining the stock fuel injector. This allows the engine to operate on 100% Diesel or 100% wood gas (or dual-fuel). Incidentally, this engine could be fueled by any combustible gas with sufficient octane rating (ethanol would work, maybe natural gas) and any Diesel fuel oil (vegetable oil, heating oil, transmission fluid, lube oil - or at least mixtures of these would work). It's hard to imagine a more versatile and rugged off grid power plant, particularly when extreme heat recovery is used.

VIDEO: http://www.youtube.com/watch?v=b7licWmX8KE

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## buenijo

U.S. source for Lister type Diesel engines (Alaska and Kansas): http://diesel-electric.us/

Powering a Lister type Diesel engine with a wood gasifier (spark ignition modification OR dual fuel) combined with heat recovery for all heating applications is among the most practical off grid power plant configurations I've yet seen. The main problem with this option is the general lack of availability of parts, and the dubious quality of machinery coming out of India. However, if one can get a hold of a good unit with spare parts, then it can be a good system. BTW, a note on Diesel fuel. I've heard claims that adding 15-20% gasoline to waste vegetable oil, then allowing a couple of days for settling, will allow all the water and many of the more dense impurities to settle out. The more dense layer of water and impurities can be drained out, or the oil/gasoline mixture can be pumped from the top. The fuel is then filtered and can then be used directly as Diesel fuel (the quick and easy biodiesel solution). I don't know how well it works as I haven't done it, but here is a forum where it is discussed: http://beyondbiodiesel.org/forum/index.php . I've heard one claim that many other oils can be blended in the same manner (lube oil, hydraulic oil, transmission oil). This should interest those considering a wood gas/Diesel dual-fuel configuration.

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## buenijo

http://www.youtube.com/user/flash001USA/videos

See the linked youtube channel for some great videos on building a wood gasifier. A few things this guy did to simplify the design are particularly noteworthy. First, he was able to minimize the welding requirements. This guy had never welded before starting his gasifier project, and he did all his welding with the cheapest possible welding equipment he could get a hold of. All joints that did not require welding he was able to seal with high temperature RTV silicone and/or gaskets. Second, the way he formed the hearth is particularly interesting. He uses a mixture of sand and plaster of paris to add a thermal mass and some insulation. Third, he makes use of existing components well. Finally, his videos provide a step by step on the process he uses to fabricate the system. He also provides a generator run test and even measures fuel consumption rates.

Also, note that he uses a single nozzle to provide air to the hearth, and he does not penetrate the hearth region for this. Rather, he runs piping down inside the fuel hopper with the nozzle directed into the hearth. This is an excellent idea, and I considered a similar approach using several lengths of steel tubing that can direct air down into the hearth via the hopper with minimal obstruction to the fuel (the minimize the possibility of bridging). I recommend using stainless steel tubing for this and this approach will allow for easily adjusting the position of the "nozzles" (i.e. the end of the tubes at the hearth) for testing.

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## buenijo

A controlled test was performed at Auburn University to measure the efficiency of a truck fueled by wood. The vehicle is a Dodge Dakota owned by Wayne Keith. The test entailed driving the truck at 50-55 mph on level ground, then measuring the fuel consumption. The consumption of wood gas was then compared to the consumption of gasoline under the same conditions (note that the truck in question also runs on gasoline). The result was 21 mpg on gasoline and 29 mpg equivalent on wood gas. In other words, the truck required 37% more energy in the form of gasoline to travel a set distance as compared to wood gas. Now, the thermal losses from the gasifier system was not factored in this case. When these losses of about 20-30% are considered, then the overall mpg equivalent on wood comes to approximately 20-23 mpg. In other words, this test showed equal or higher overall efficiency on wood compared to gasoline. Folks, this is just plain amazing.

The reason these results were obtained is partly because wood gas burns slower than gasoline vapors. The engine in this relatively small truck is an 8 cylinder engine that has to work at a relatively low speed and at a relatively low output relative to its rated hp. Under these conditions the efficiency of the engine on gasoline is quite low. However, the conditions are favorable for wood gas. Since the engine was operated at the same speed and average cylinder pressure during the test (55 mph on level ground), then I've considered only three explanations for the results. (1) the simpler fuel gases available in wood gas (CO and H2) were more completely combusted, and/or (2) the slower combustion of wood gas delayed combustion during the power strokes to reduce peak cylinder temperatures (to understand this effect, consider that a very rapid burning fuel would see more combustion while the piston is near the top of the cylinder - this would result in higher peak temperatures which would transfer more heat to the coolant - this would lead to lower cylinder pressure as expansion continues and would lower the average engine torque - this would require more fuel to be burned as compensation to maintain the same average cylinder pressure and keep the engine power constant), and/or (3) there is reduced pumping losses when wood gas is used (wood gas has low energy density, so perhaps the throttle was open a great deal more to admit the require mass flow rate of gases including air and wood gas). Most likely it's a combination of these factors. Now, I expect the results to be quite different under different conditions. For example, if the engine were operated where efficiency is highest with gasoline, then I expect the efficiency would be poor on wood gas. 

The results of this test led me to consider more favorably the idea that a vehicle can be fueled effectively and efficiently on wood. In particular, I believe a dual-fuel configuration might be ideal. In this case, a relatively small wood gasifier is used to supplement fuel to a conventional vehicle. The idea here is that, since the vehicle requires no more than 20 hp or so to maintain speed on level ground in most cases, then wood can be the dominant fuel whenever the vehicle is cruising. However, gasoline is available for higher power to achieve greater acceleration and hill climbing as required. The configuration is to admit a wood gas/air mixture to the intake manifold past the MAP sensor, then operate two separate throttles: one for the wood gas/air mixture, and the stock accelerator pedal. The wood gas/air throttle is not allowed to fully shut during operation (use a mechanical stop). The purpose is to allow just enough air flow through the gasifier to keep it hot during operation. So, imagine a hand throttle on the steering column for the wood gas. After accelerating to speed, the wood gas throttle can be operated with the gas pedal slowly released (or both could be operated in tandem during acceleration, or just use wood gas for slow acceleration). Since the majority of fuel is consumed while cruising, then it stands to reason that this approach could replace most of the gasoline consumption with wood. Also, according to the test here, it seems reasonable that the efficiency on wood can be high at low engine outputs typical with cruising on level ground. A major benefit is the ability to use a smaller gasifier, and in particular a smaller gas cooling and filtration system as compared to what is required to power a vehicle on 100% wood with good performance. Also, it seems likely that good results can be obtained with a four cylinder engine (there are many more compact pickups available with 4 cylinder engines - a 100% wood gas truck will not do well without a large engine).

http://driveonwood.com/sites/default...l%20Report.pdf

Wayne Keith's truck: http://www.youtube.com/watch?v=JlNACAEa3vo

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## buenijo

I've come to view these wood gasifiers in a particular way that seems to simplify things. I now consider them as charcoal gasifiers that process pyrolysis gases in addition to combustion gases. Charcoal gasification was covered in previous posts. Air enters these units and the oxygen reacts with the surface of the charcoal to generate combustion gases (primarily CO2). The CO2 is then reduced in the high temperature carbon environment to form CO (the fuel gas). What little moisture is available (in the air or some water in the charcoal) is likely reduced as well to CO and H2, but CO is the main fuel gas produced here. It was mentioned that engine exhaust gases are sometimes introduced to a charcoal reactor (with the intake air). This is done primarily to moderate the extremely high temperatures in a charcoal gasifier, but it also increases efficiency significantly. After all, it increases the supply of CO2 to the charcoal. Since the reduction of CO2 to CO is endothermic, then it serves to reduce temperatures by converting heat to additional chemical energy in the form of additional CO fuel gas (an elegant solution to temperature control). Note that steam can also be admitted with the intake air to moderate the high temperatures, and this will increase H2 production.

With this in mind, now consider a wood gasifier as a charcoal gasifier. In a downdraft wood gasifier there is charcoal at and below the nozzles, and wood above the nozzles. When the wood gasifier is first started it is the charcoal that is ignited just as in a charcoal gasifier. As the temperature rises, then the wood starts to enter pyrolysis (gets converted to charcoal by releasing water and volatiles/pyrolysis gases/tar vapors). At this point the combustion of charcoal slows and the combustion of pyrolysis gases begins. Eventually, very little of the charcoal is consumed in combustion. Rather, the charcoal is consumed in the reduction of the combustion gases CO2 and H2O (C + CO2 => 2CO , C + H2O => CO + H2). These reactions are endothermic meaning they consume heat to drop temperature, so it's extremely important to insulate against heat loss at the hearth. An important consideration is that wood contains such a high proportion of volatiles that it's difficult or impossible to combust all the pyrolysis gases generated. Therefore, peak temperatures must be very high to crack the tar vapors not incinerated at the nozzles. If temperatures fall, then the likelihood of introducing tar vapors with fuel gas rises, and the energy density of the gas can fall (lower proportion of fuel gases generated). So, basically the task is simplified to considering a wood gasifier as a charcoal gasifier that generates it's own charcoal from wood real time (in situ), and the task is to retain heat and keep the temperature high enough to ensure a quality gas. Other considerations beyond insulation include:

1. Making sure the wood is as dry as practical. Free water is very good at dropping temperatures.
2. Making sure the wood is properly sized to prevent bridging (make sure it flows well - if it gets hung up, then the charcoal can be consumed leading to excessive temperatures and poor gas quality - the wood fuel can then get freed up and fall on the hot charcoal and dump tar vapors through the system). So, wood pieces should not be too large and not irregularly shaped (fines, etc.).
3. Making sure the wood is properly sized to ensure good combustion of tar vapors. If fuel is too small, then the air may not penetrate the fuel bed and react with the available tar vapors. As much of the tar should be burned as possible at the hearth to achieve high temperatures and save charcoal for gas processing. High peak temperatures are important to crack whatever tars are not burned. Note that nozzle size and orientation play a critical role in making sure air penetrates the fuel bed. 
4. Air preheating. The hot fuel gases can be used to heat the combustion air to high temperature before it enters the nozzles. Since the mass flow rate of the fuel gases is higher than that of the air, then the air can be taken up to nearly the same temperature as the fuel gases. A lot of heat can be regenerated into the system this way. At first this process will increase the rate of wood pyrolysis. However, a new equilibrium condition will be established where the level of charcoal in the system rises. The result is that charcoal (an excellent insulator) will shield some of the wood from the heat and slow the rate of pyrolysis back down to the previous level. The final result is that more heat is added to the combustion zone which increases peak temperatures. This helps to crack tars that are not combusted, and it adds heat to the reduction zone. The result is a richer fuel gas and enhanced tar cracking ability (i.e. a more efficient gasifier and cleaner gas, all else equal). 

In my opinion, a good wood gasifier will be had by emphasizing these points: sizing wood properly, using very dry wood, sizing and positioning nozzles to penetrate fuel bed with air, super insulation at the hearth, aggressive air preheating, deep charcoal bed, running system within proper turndown ratio. Beyond this is the matter of fuel gas filtration which should be relatively simple with a good gasifier that makes little or no tar, and fuel gas cooling which is simpler with air preheating.

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## buenijo

http://www.vaillant-export.com/homeo...y/development/

An interesting system for residential heating applications is being developed in Germany using zeolite desiccant. This is fundamentally very similar to configurations I discussed in previous posts where the waste heat from a wood gas engine system is used to regenerate zeolite (or silica gel) for heating or cooling applications. The system in question uses natural gas to regenerate the zeolite. The steam driven off the zeolite is condensed to provide heat, and once regenerated the water vapor that evaporates off the condenser (a store of water) generates additional heat through adsorption. 

Personally, I am interested in this process for optimizing net energy recovery from a small wood gas engine system operated intermittently (daily) to bulk charge a battery system (and I've mentioned the prospect in previous posts). I like the prospect of achieving a relatively simple and low tech off-grid home combined heat and power system. The ideal system in my mind would use a direct current electrical system and minimize the use of electronics (like battery charge controllers and inverters - to avoid additional energy losses, reduce costs, increase simplicity and reliability), and most important it would have to be extremely efficient in making use of wood fuel. Photovoltaic systems are fantastic for off grid power, but I still find myself fascinated with the prospect of achieving the same end with low tech hardware. Perhaps there is a place for this approach in some settings.

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## buenijo

I considered recently that it may be cost effective to power a small coal gasifier engine system in the off grid setting using anthracite coal. It turns out that home heating with coal is still fairly popular in some regions, and processed anthracite coal in 50 pound shrink wrapped bags is sold at reasonable pricing. The main problem is the costs involved in shipping if one is not near the source. Good news is that anthracite stores indefinitely. So, it's possible in principle to purchase a large quantity of this fuel source and put it in storage. I need to do more research on this fuel source, but all information I have available so far suggests that pea gravel sized anthracite coal could work very well in a gasifier engine system. If it can be had cheaper than alternatives, then perhaps it should be considered seriously as a viable energy source for remote living.

Video of rice coal home delivery ("rice" refers to sizing - this is anthracite): http://www.youtube.com/watch?v=JlOFA81rhxg

NOTE: It might be that a high quality bituminous coal would work well. The benefit here is that many more regions produce this grade of coal where sources for anthracite are very limited.

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## buenijo

New gasifier stoves:

www.youtube.com/v/m_jWz3H-48M

www.youtube.com/v/-mEMZ8UE7oY

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## buenijo

Interesting gasifier: https://www.youtube.com/watch?v=HrbrTWGwY0w

The basic idea here seems similar to what Lifesoup was working on where raw biomass is added to a charcoal gasifier. There is no reason whatever that such a process cannot be sustained indefinitely such that charcoal never need be generated directly - after all, this is what a wood gasifier does (generates charcoal from wood as it goes). The benefit of using a charcoal gasifier and adding biomass is fewer tar vapors to deal with. It seems this approach attempts to add biomass at a controlled rate to prevent having to generate charcoal and to generate a tar free fuel gas with a relatively simple design. The problem as I see it is a reliance on a highly refined fuel (pellets, small chips) and having to feed the fuel at a controlled rate (which will finally require automation). Also, if not precisely controlled, then one would have to generate charcoal separately, and I don't consider that to be practical.

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## Ronin Truth

You don't want to be behind them at a stop light.

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## buenijo

> You don't want to be behind them at a stop light.


True!  However, this system is for stationary use.

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## Lifesoup

I'm cracking ~1.3 gallons of water per hour to run a generator that uses roughly the equivalent in gasoline - when it's running on gasoline.  The water is displacing N2 from the intake charge.  The combination of increased H2 content and reduced N2 makes for some potent gas. Also char sublimation is notably reduced.

It's still not as potent as gasoline, but it is approaching.  I make no modifications to engine timing or compression.  I always want to be able to valve back to gasoline at will.  However if the engine were tuned for this biogas, no doubt the comparison would be even closer.

You could probably stand getting behind me at a light.

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