It is a brew of complex organics, principally acids with poor energy output characteristics.
The production process gives us two product streams. One is char, whether charcoal or biochar and the so called biofuel. The most energetic components, the volatiles are typically burned in the actual production process. Advanced processes can apply pressure and additional heat to improve the output by reforming the complex organics into better grade fuels like hopefully methane. All this consumes a lot of the available energy.
It all likely ends up as slightly superior to coal gasification but that is faint praise. It remains an option that is used because you have no choice and someone is prepared to subsidize it.
What it has going for it is that there is little patent protection possible, so you and I can waltz into a funding source and ask for gobs of money to build a plant. There will be a lot of such folks, just as in the ethanol boom, who will round up the necessary funds on this tale of joy and build away. They will all lose money, just as ethanol is doing today.
The point that I need to make is that even if it can be made to operate profitably, which is not totally unreasonable, the capital is unlikely to ever be recovered. Otherwise, there would already be thousands around the country long since paid of.
My real regret is that this is a diversion of capital from projects that deserve every penny of support.
I would far rather see a drive on creating cattail paddies that produce massive amounts of starch as ethanol feedstock. It would also employ thousands and not interfere with food production.
More importantly, the electric car is now imminent. We need a massive increase in base grid power on top of the rapidly expanding solar and wind sources.
We need to hugely expand geothermal energy production in the state of Nevada. Power plants can be built there readily and as often as necessary. What is most important, there is nothing to invent. Of course, we can expect some meathead to redo Icelandic history by using cheap steel inappropriately. The rest will not.
Very shortly someone will be asking why nothing was done for the past several years to prepare for the looming energy crunch.