Refining ethanol from wood waste has been an ongoing research topic around here for awhile.
So far though it seems to take almost as much energy to produce as it would make.
According to the article below, a researcher has discovered a new way of extracting energy from "biomass" - you know that stuff you have left over after pruning or removals.
Perhaps in the future, we can begin selling the stuff or using it to run our vehicles.
TG Daily - Does gasoline grow on trees?