wood gas vs biomas digester

Which is more efficient, a biomass digester or a wood gasifyer? I would assume that if a digester was running on manure, then it would use less land; the manure is a waste product, and can still be used as a fertilizer afterwards. However, a gasifyer could produce gas on demand, unlike a digester, which takes a while to get going and is a continuous process. Also, I have seen wood gasifyers built into the back of trucks, and I would imagine that carrying around a tank of manure slurry would be difficult.

How much coppice woodland would be required per mile driven with a wood gas truck? I know there are a lot of variables, but a ballpark number?

I think the two technologies don't compete because they use different feedstocks. Wood is more dense requiring heat to break it down, whereas digesters work on simpler feedstocks, so microbes are fine. Both are great if you have the feedstock to use.

Driving on wood uses about 2 lbs per mile. From that number you can determine how many miles you will drive and how much wood weight per acre to get the number you are after.

The gas on demand part is really cool. In a few minutes you are ready to go!