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.
