These days there are a wide array of different BioFuels, such as - Wood - Dung - Alcohol
and so on.
BioFuels have one big advantage, which is that they are generally capable of being Renewable, although this does not mean that the necessarily are. If you chop down an entire woodland EcoSystem and then burn it, you will got lots of Energy from it, but it will take a hell of a long time to grow back, if it ever does.
BioFuels will have an increasingly more important role as an EnergySource in future. They have been rather overtaken in the last 150 years by FossilFuelss and more recently NuclearFuel.
At heart, BioFuel can be considered to be a form of SolarPower as nearly all life comes at some point from photosynthesis.
Most of the ChemicalEnergy in BioFuels is released by the formation of CarbonDioxide. This tends to release a lot more Energy than Hydrogen Combustion. Although CarbonDioxide is a greenhouse gas, this is not polluting if the BioFuel comes from a Renewable source as the CarbonDioxide will have come from the atomosphere when the plant grew.
BioFuels are therefore a fairly dense form of Energy. They can be used were the space or weight of the Fuel are a key issue—the most obvious example here is in Transport. BioFuels are already in use in this way. There has been quite a lot of research into VegetableOil based InternalCombustionEngines, as well as Alcohol supplemented Petrol, which at least makes the NonRenewable resources go further.
Most BioFuels are solid, which makes then difficult to move around—at least within a pipe. However, there are ways around this. You can convert to Alcohol through a Fermentation process, or to Methane rich gas through Gassificiation, or an AnaerobicDigestionPlant.