Woody Gasifier: Off-grid with just wood?

Wood goes in, gas comes out

Wood goes in, gas comes out

Biomass is currently used to create electricity in many places in the U.S.  The process is fairly simple.  Chop down some trees (a renewable resource), burn them (with the required air permits), create electricity.  While sometimes the trees burn in a boiler to create steam which turns a turbine, it is also possible to break the tree into a gas, and burn the gas directly in a turbine (like a natural gas engine). While this is being done on the MW scale, I was intrigued when I saw this product pop into my inbox:

The Off Gridder is the first multi-fuel gasifier for the home power generation market.  Using wood pellets, wood chunks, chips and certain types of agricultural waste, it is able to meet the power needs of an efficient home in as little as 2-4 hours a day.  Beneficial bi-products include heat for hot water and biochar for gardening.

I was pretty intrigued by the Off Gridder at this point, so I checked out the website at  So basically you put in wood, let the thing warm up, and then you get some gas.  But the gas alone isn't enough.  You'll have to buy a generator to pipe the gas into, then the gas is burned in a combustion chamber, which moves a piston, that turns a turbine, which creates the electricity.  So while the Off Gridder will get you half way there, you will still have to invest in a generator.  Diesel generators are usually used in times of emergency power.  In this case you are just replacing the diesel fuel with wood gas.

While this is not a new idea or technology, an actual biomass gasifier for residential use is a pretty new application.  The creator of the Off Gridder (who also created Victory Gas Works - an online community for Gasification.  A very niche community...), Ben Peterson, was featured in September's Popular Mechanics as one of 10 Incredibly Cool DIY Projects.

After checking out the Off Gridder website, I think this is actual a pretty cool device for people serious about creating their own energy...with two caveats:  1.) you have to live around a lot of trees that you don't mind chopping down and using for feedstock and 2.) I hope you don't have many neighbors who mind listening to a generator for a few hours each day.  So basically, this device is great if you live in the woods.  But most people who want to get completely off the grid do live in the middle of the woods, so in that case, this could be the perfect fit.

***Update - 9/28/09 - I contacted Ben at to ask about any suggested generators people can use with the Off Gridder and here was his response:

Thanks for the awesome write up. I put together a page on engines here:
and force people to go through it on the way to the sales page so that they are educated about the product.

For power and fuel economy I think a 4 cylinder natural gas generator in the 30 kw range is ideal. Derate to about 60% with woodgas, making 17-18kw. I like the older stuff you find on ebay for about $2,000 with only a few hundred hours of run time. Westerbeke makes good gensets, but they are a little more expensive.

Slow speed generators running at 1800 rpm are much quieter than the little 3600 rpm buzz machines. They last longer too.

So I have to say, the more I learn about this product the more intriguing it becomes.  Unfortunately it is more of a hands on type project, but if you like to tinker, it could be a pretty neat DIY.  Also, Ben got back to me within an hour, so you know they have a good focus on the customer.  I also thought it was pretty cool that he puts on a workshop to help people learn about the product:

I wonder if anyone has thought of becoming an Off Gridder installer, much like you currently have Solar installers?

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Dave and Chris. Wood gas is actually a mixture of Hydrogen gas and carbon monoxide. There is no need for hydrogen generator.
Hi I'm Hugues from Nortern Quebec, Canada. I decided to move from the big city to live full time at my cottage. We are in the middle of the woods no city hydro. So I've spent lots of money in solar panels batteries, wind turbine and of course generators. Well we had a really hard winter not a lot of sun, hardly no wind just cold and lots of snow. So needless to say our little generator had quite the work out and it cost me a small fortune in gas. That's what brings me here, I've been looking everywhere for a good gasifier design and so far looks like Woody gasifier is a good place to start, but the website is no longer and I can't find the blue prints anywhere. Do you know where I can find them and also do you have any suggesting on other gasifiers, docs and video tutorials. Thanks in Advance Hugues
ckmapawatt's picture
Hugues, Try this site: or try this community: You could always just use a <a href="" rel="nofollow">bicycle power generator</a> :)
Seems to me that you could hook to grid and push far more in during the day than you could ever use during the night. If a solar grid was also in the mix it would really be close to geting paid for your power,and how good would that be? I wish I could buy a big enough grid that it would pay for itself on a pc of property I have that is perfect for them,but am unable to move on it yet. Think that is possible? I know I am off topic but its All about going off the grid in the long run. LOVE the woody going to get one,just wish I could use that heat to heat the house along with the generator use. Since I heat with wood totally any how,have for 15 yrs are more. Thanks Bill monteith-
Great sites thanks But I was looking for an small unit like the one showed in the pictures above. Are the blue prints available on the net ? Thanks in advance
Chris: I was wondering about adding a hydrogen generator to the mix, if that might add to the engine performance.
ckmapawatt's picture
Dave, can you elaborate on hydrogen generator? Would this be something external that you would hook up to the woody gasifier that would pump hydrogen into the wood gas? If so, how would you create the hydrogen? Here's are post on <a href="" rel="nofollow">natural gas fuel cells</a>.
Can you give me an approximate wood consumption for a 24 hour period on a 7kw generator? Thanks, Rick
I am looking for a gasifier for a match with my whole house generator I could buy. Can you get back to me with a good match and pricing? Thanks TOM
ckmapawatt's picture
Tom, Check out our updated post on<a href="" rel="nofollow"> Electricity from Trees</a>.


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