Pillar to Post: Peter Welander's Blog
News and comment from Control Engineering process industries editor, Peter Welander
Your next home appliance: bio-gas generator
January 26, 2010
Last Sunday, Joe gave me the results of some searching he’d done on the Internet about wood gas generators. (We discuss this topic frequently, and I keep telling him that I can’t believe he’s never dabbled in it given all his other interests.) Anyhow, apparently there’s a company in China that manufactures a commercially built wood gas generator with the catchy name JXQ-10A, designed to power a stove for heating and cooking.
I asked Kevin Chisholm of Wattpower what these appliances cost. He says, “We import them from China, for distribution throughout North America, and arrange shipping to the container unloading terminal nearest the customer’s location, in that they are shipped in ‘less than container load’ (LCL) lots. For simplicity, this can be called ‘the major freight terminal nearest you.’ The cost at this point is about $1,250, depending when the order is placed, the value of the U.S. dollar, etc. The customer looks after terminal charges, local taxes, his broker, and local delivery charges.”
From what I can tell, the unit has a cylindrical tank that’s about 48 in. tall and 18 in. diameter for the fuel. Next to it is a gas cooler and filter unit that is shorter and wider. It has a self-contained electric blower to suck air through the burner tank and pressurize it for delivery. You fill the tank with wood chips or whatever fuel is handy and light it from the bottom. Once the burning is stabilized, you can pull gas out of the chamber, cool it, and send it to the two-burner stove to cook dinner. Various reports say it is good for several hours of operation.
This makes a lot of sense. I can imagine that out in rural areas of China such a generator would be hugely practical. Compared to an old-fashioned wood-burning cook stove, this would be very sophisticated and probably much cheaper than trying to buy propane or butane. Users caution against trying to feed this gas into an engine. It carries much tar which accumulates in the cylinders and can ultimately glue everything together. Those that insist on using it with an engine say that with regular enough cleaning, the engine will continue to work. Flat-head engines (like the one on Joe’s sawmill) are preferred for this service since it’s easier to take the head off.
There are more sophisticated units built domestically that have additional filtration to remove tar so the gas can be fed directly to an engine without the ill effects. There are areas where wood, forest residue, and agricultural leftovers are abundant and effectively free. Moreover, using bio-scrap avoids the need to consume fossil fuels.
The downside is that wood gas has lots of carbon monoxide and tends to be a trifle carcinogenic. You really don’t want your gas generator indoors. Is this sort of thing for everybody? Maybe not, but short of having a neighborhood nuclear reactor or ethanol distillery in the basement, this offers one of the only practical approaches for using your own biofuels outside of having a fireplace in the living room.