Biomass itself is not used directly, instead you can convert it into useful fuels using catalysis. There you take the feedstock and do chemistry over a catalyst to generate, say, CO2 and Hydrogen (called syn gas) which can then be used to make methanol (CH3OH) which is a great fuel, or ethanol.
You might also get CO and water which can be transformed into CO2 (a feedstock) and hydrogen for fuel cells.
So biomass is a bit like oil – you have to use it as a starting point to obtain the fuels you want.
But it is easier to produce and process and more sustainable. We are starting a big European Union funded project next week to work on this topic!