Wood logs

Hi Ben
I have been reading about gasifiers for a while and it is my hope to ond day be able to start building my own gasifier.
My question concerns fuel. What do you think about the possibility of using logs instead of pellets or chips? Is there a maximum size for fuel?

Thanks for sharing your knowledge!

cghallberg

Yes there is a size requirement for the wood. It takes alot of air to break down a log. Its too slow to make motor fuel from. It definitely works for boilers, but they burn the gas as soon as it's made, we capture gas.

Using chunks ranging in size from "two thumbs" to a "small fist" is ideal. Pellets vary by quality and tend to fall apart, but there is a process that makes them work called torrefaction where the water and oils are baked out and the wood is nearly as energy dense as coal. Unfortunately you can't easily buy torrefied pellets, but they are the way of the future.

You can screen wood chips to get the fattest one out, but its not any faster than chunking and chips weigh less, so they make less gas.

Wood chunks are best, there are some good videos on youtube if you look for "wood chunking." There is a guy that can split and chunk wood with a tractor pto and a kinetic log splitter. Pretty cool.