This page will not get into the How-To’s of gasification or too deeply into the physics of it. I am not a scientist or engineer -I’m just a concerned guy living in Suburbia who happens to know alot of cool people that like to weld. What this page WILL get into is why I am convinced that gasification is a paradigm shifting technology.
We should start with a VERY high level description of how wood chips can power an Internal Combustion Engine (ICE). When carbon burns (the wood chips in this case) you create water vapor and carbon dioxide as moke, along with what ever other pollutant were in the wood -and you also get a bunch of heat. Gasification takes these three by products of pyrolosis and uses them to fuel a second reaction by concentrating the heat onto a bed of charcoal. These coals reach 1800+ degrees in the gasifier, which is hot enough to break the water vapor into hydrogen, and the CO2 into carbon monoxide. Both of these gases are combustible. The rest of the gasifier is then designed to first cool the gas -a cooler gas is more dense- to under 100 degrees, and to filter out any remaining water vapor and tar. The resulting vapor is 20% Hydrogen, 20% Carbon Monoxide, and roughly 60% Nitrogen which is merely a background gas. When under 100 degrees or so, this mixture is roughly 118 Octane and will run an ICE with a modified carb that will accept a 1:1 air/fuel mix. The Gen Gas site and our Videos go into MUCH more detail. The model in the videos is sized to run a 30hp engine, which should be enough to power a 15kw generator on about 10 #’s of chips/hour.
So, with the intro done, I’d like ot explain more why I think gasifiers rock.
First off, Gasification -in its current state- is open source and grass roots. Most of the people cobbling together gasifiers are normal Joe’s and Jane’s: backyard tinkerers. Using the FEMA plans (located in the Resource Page) normal people, using normal tools like welders and saber saws and normal items like steel drums and pipe, can make a fully functioning wood chip gasifier just like we did in a few days of work. No CAD designs, no high tech fibers imported from China, just good old grime under the nails tinkering. The plans are free, the parts are usually salvaged, and the skills are not hard to come by. What I find exciting about it is that you and I – WE can make our OWN energy at home for little money. And if you build it yourself, you can fix it yourself should it break. And since you built it, sourcing parts is no problem.
Secondly, Gasification makes both electricity and heat in one unit, simultaneously. I guess to be entirely honest -it makes heat and syngas, but as our design is for a Co-Gen unit I will stick to the oversimplification. Most energy systems today do one or the other. You can heat your home with a wood burner or masonry stove, but you still need to power the lights and computers with something. PV and Solar are getting slicker by the year, but both are still very expensive. Making hot water from a PV unit is costly, and while dumping excess wind energy into a hot water tank is fairly common, as we are using the waste heat from the gasification process to heat a home it will always be availible whenever we are using the unit. That means we can design it into the home energy system as a main component, not just something to use as an extra should we have a surplus of wind. I like that alot. The final two are my favorites though.
Fuel. Using the data we’ve gathered for burn rates, burning our gasifier 2000 hours a year (40 hrs/wk, 50 weeks a year) will use about 20,000#’s of wood. As the gasifier runs well on softwoods, it is possible to establish a “coppice” forestry system to grow your own fuel should you have access to land. In a Coppice System, decidious softwoods are grown rather than coniferous trees as is most common in American Forestry. Softwoods like Maple, Willow, Box Elder, Poplar, etc will regrow from their stumps after their trunks are harvested. This means that the root structure is in place after harvest and no replanting is needed. Because the full root system is there, the regrowth is very vigorous -as anyone trying to cut down a Box Elder knows! This means that once your wood needs are known it is possible to set up a rotational stand of trees where one row is cut every year -you cut the first row, then move to the second row the next year while the first resprouts. If you designed you plot right, by the time you get to the end of your plot, the first row has regrown to a sufficient thickness that you can start over -now THAT is sustainable forestry! Entire industries could be rebuilt on woodchips as a fuel source. In Europe, coppice plantings of Hybrid Willow net about 60,000 #’s of chips every 3 years per acre – so roughly 1 acre of willow trees will be needed to run a gasifier this long. 2000 of run time with a new Generac generator would net about 35,000 KWh of energy – 2x what an efficient, modest home uses!
Bio-Char. The main “waste” product from gasification is that for every pound of chips you put in, you get about .5 pounds of charcoal out the bottom. Luckily this charcoal has ALOT of uses. It can filter water, it can be used as a secondary fuel source (it cooks veggie brats nicely!), or it can be used to create Terra Preta or Bio-Char. Terra Preta is so cool I plan on dedicating a whole page to it, suffice it to say that it seemingly enables soils to lock their fertility in for millenia as the charcoal prevents leaching. HUGELY exciting for us sustainable farmers! Also, Charcoal is very stable –essentially 50% of the carbon input into a gasification system is sequestered for centuries … we begin to heal the atmosphere with every KW of energy we produce with these systems!!!
So there you have it: Do it yourself Co-Gen using renewable, sustainably grown forestry products whose end product is not only electricity and heat for your home, but Bio Char that will allow you to farm sustainably for generations in a way that actually pulls more carbon from the air than it emits.
Be the Change!