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Wood gasification: Not how, but whether  RSS feed

 
Micky Ewing
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Location: Merrickville, Ontario
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This is not a fair question for our guest author, Ben Peterson, but it's one that bothers me a great deal so I feel compelled to ask. For me the biggest question about wood gasification is not how, but whether.

The destruction of the worlds forests is already one of the major problems of our time and is leading to huge increases in desertification, soil loss, flash flooding and green house gas emissions. Now, with fossil fuels becoming less affordable (fracking bubbles notwithstanding), people may turn to wood gasification to try to keep all the engines running. And the truth is that we would quickly strip the entire tree cover of the planet if we simply switch from oil to wood.

So, Ben, my question is this: would it not be better for us all to curb our appetite for energy rather than burning up our forests in an effort to extend our happy motoring for another few years? Like I said, not a fair question. Nevertheless, I would like to hear your thoughts and other peoples' as well. If nothing else, I will feel better having raised the issue in people's minds.
 
Ben Peterson
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Micky,

Fair points to raise. Since you need dried wood it's really best to used seasoned wood thats already dead on the ground. Branches are already a sized diameter and just need to be cut to length. There are plenty of dead trees from windstorms in my area but maybe not yours. Prescott AZ would be an example of a place with some trees, but not an abundance of tree waste. There is ton's of construction debris for the taking.

The reason wood gassers won't destroy the world's forests is because chunking wood takes time and energy and as such we want to do it as little as possible. Its a feedback loop. The more we burn, the more we work. A year of wood gassing will get your mind thinking about efficiency.

I am working on a house design that will consume just a sip of energy, so I can hopefully power many houses from one gasifier/ solar array. Efficiency is the cheapest form of energy. Thicker walls, passive gain and simpler appliances are easy ways to get there. So to answer your other question: "Yes we should curb our appetite"

Our commuting lifestyles are the real energy drain on society. If we could get back to communities where all the tools you need to make a living are close, then we could dramatically shrink our energy use. People tend to live where they can get jobs. We have to brings the jobs out to the people better.
 
                    
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Location: AR ~ozark mountain range~zone7a
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I doubt gasifiers are even making a dent in forest supply, because gasifiers are simply not in widespread use...hard to say what the future holds. But forestation or biomass is readily renewable, 'stored solar energy' that is to say recently stored solar energy...verses the petroleum fuel based on ancient stored solar energy. Hybrids of renewable & ancient fuel are in use in mobile applications, at this time, so there is that to consider also. Also if you have noticed the RMH type stove is claimed right here at Permies.com to burn at rates 10X less fuel is required, as compared to a normal camp fire...so a gasifier does also use much less wood fuel/BTU as compared to a normal camp fire. That is because of the efficiency of the set-up, which determines fuel consumption rate.

As far as what Elliot Harrah was referring to, I think he brings a good point that I too am also interested in, 'cracking temperature'...and I would ask Ben Peterson, has there been any practical english speaking examples of using catalyst after the woodgas hearth? {I know the typical automotive catalytic converter was not yet invented back in the 1930-40's} And if so, perhaps Ben would like to share his experience using catalysts applied to gasifiers. I am wondering why automotive catalytic converters are not used more often on their gasifiers to further crack the CO2, just off the hearth, before any cyclone or other type condensers. Here is a video of what I am referring to. And while I'm asking questions, how come typical gasifiers are not using firebrick in the hearth area, there again, to increase smoke temps? https://www.youtube.com/watch?v=VKJzMjhuoKw

james beam

 
Micky Ewing
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Location: Merrickville, Ontario
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Thanks, Ben and James, for your replies.

Ben, I'm glad to hear that efficiency is a high priority for you, and I agree that big gains could be made by reorganizing our communities and economies. Your assurances regarding the abundance of dead wood and the limiting effect of the high labor cost of gasification are not very convincing though. Re. dead wood, any permie will tell you that dead wood plays a vital part in forest health. Also, if dead wood is in short supply, people will "make" dead wood from living wood. With relatively little time and effort, a few dozen or a few hundred trees can be girdled with an axe or chainsaw and they will be quite dead by next year.

Regarding high labor input, well, automation has played a big part in the destruction of our forests, and I see no reason why this would change. A wood chipper run on wood gas, or a machine like the one in this video are both "great" labor-saving devices.



Just imagine a hybrid of Exxon and Domtar operating at 10,000x this scale and you will get an idea of the sort of threat I foresee. Not that any of that is really necessary. We were doing a fine job of razing the forests long before the chain saw came along. And that was just when we were using the wood for cooking, heating and building. Imagine how much worse it will be if we are also trying to fuel our fleets of cars, trucks and tractors, let alone our power plants and factories.

 
William Bronson
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Location: Cincinnati, Ohio,Price Hill 45205
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I have a question.
At what point is energy use low enough? Should one have IV lines , internet,rocket stoves?
Each requires energy,and using any of them uses resources.
I think woodgas is as woodgas does.
It could be a part of a sustainable local system or the next cause o deforestation.

Woodgas might save the oil that iwould be needed to medivac my child.
It could also increase the particulates that plague myself as an asthmatic
 
Ben Peterson
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Good questions:

If woodgas was going to raze our forests it would have done it by now. There was much more widespread use of this tech 100 years ago. The economy of woodgas makes it suck for big business because the energy is spread out. An oil field is a huge puddle of energy that just needs to be slurped up with a pipeline, so the economy of it works better.

For individuals however walking out to the back 40 for an arm full of wood can work.

When we take wood from the forest we don't have use for the small scrubby stuff, so it can get left. To live is to use energy. If you want to leave branches on the ground in your neighborhood thats cool, but your energy may come from a strip mined tar sand pit in Canada that wiped out many square miles of forest. Or one states drinking water may be getting pushed into the ground to drive out natural gas for another.

These aren't easy answers. We make an impact. So lets make the smallest impact and do the most with the opportunity we are given.

James:
Catalytic converters aren't used in gasifiers generally because the amount of soot they produce fouls the converter. There is very little C02 to crack off the hearth, but water vapor could potentially be cracked. In that video link they were breaking down plastics it said so it's a little different gig. The internal temperatures to crack oils are best at 1100 C and above. The higher the temperature, the shorter the residence time needed for the oils to fully convert from a liquid into a gas.

Charcoal is really the best low tech catalyst and it's at the heart of the system. A wood gasifier is really just a charcoal gasifier that makes its own char.

I have played with catalysts for making fuels and they are expensive to buy or time consuming to properly make and get reactive. Catalysts are an area of some really cool research and they are beginning to play a role in reducing emissions in diesel gensets and all sorts of chemical synthesis. For the average guy though its alot of cash and extra time to mess with. When solid oxide fuel cells come of age I think you will see catalysts play more of a role.

The reason that refractory brick isn't used more is because of its weight. That shit is heavy! I have done some custom cast ceramic hearths and you need a damn forklift to move the part that holds it.

Another reason you don't see firebricks is because round gasifiers are the norm. They light better and are structurally strong. Refractory bricks can work so if you have some, then play around a bit and see what they can do.

 
Rick LaJambe
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Location: Surrey, British Columbia
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With oil and natural gas, we consume it and it is gone. Wood is classified as a "renewable resource", and as such, we can replace what we used by planting more trees to grow and produce more wood. It is something that requires more foresight and planning to not end up in a situation where there is worsened deforestation,but it is something that can be managed. Oil cannot be replenished in our lifetime, but forests can.

Are permaculturalists not focused on planning for permanent abundance? We plant trees and bushes to produce our food, ground cover, building materials, animal feed and habitat. Branches fall, trees die. Mark Shepard wrote in his book that he has reached a point on his farm where they have more wood waste than they can use for home heating or woody mulch so he was looking to wood gasification to deal with what was becoming a problem; huge piles of tree and hazelnut bush trimmings. He states that trimmings from an acre of hazelnuts can produce $90 worth of electricity. "The problem is the solution"

Instead of focusing on how wood gasification would fit our current situation, wouldn't it make more sense to think about how we could make our situation fit wood gasification? One could probably calculate the number of trees they would have to personally plant every year to cover their (reduced) energy needs and plant far more. And as Ben said, it's a lot of work gathering and prepping all of that wood. Once you have done the work necessary to produce the energy for yourself, you are going to appreciate it more and be much more conservative. It's no different than growing your own food. Once you understand the effort that went into growing the meal on your plate, you appreciate it more and waste less.
 
Micky Ewing
Posts: 105
Location: Merrickville, Ontario
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Thanks to everyone for the replies. William, your question is at the heart of the matter but I would give it a small edit and throw it back at you:

At what point is energy use low enough?


For humanity as a whole, the answer seems to be "never". That's no different than for any other species, but with our ability to reason and foresee the consequences of our collective action, perhaps we have the motivation and the ability to change.

I prefaced my original question with the admission that it wasn't a fair one. That's because it's not really about wood gasifiers; it's about society's ability to regulate itself. We really have to get a firmer grip over how our resources are managed, including our forest resources. Logging companies have always deflected criticism with the claim that forests are a renewable resource. While that is true in theory, it has yet do be demonstrated for more than a generation or two by anyone except indigenous peoples isolated from the remorseless encroachment of Western civilization. That has to change.

OK, I better getting off my soapbox now, before I start talking politics and get myself banned!

 
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