I think the main hurdle to using biofuels is reducing the cost of enzymes used to break down cellulose. ("cellulases"). https://en.wikipedia.org/wiki/Cellulase
Plenty of biomass is available, but it is necessary to break down cellulose. That's hard, because nature has evolved cellulose to be very resistant to breakdown: (Why else can 1000+ year old trees exist; their central cellulose lasted that long without breaking down.)
This is first done by mechanical crushing, and then by breaking down some of the cellulose bonds employing inorganic acids, such as hydrochloric and sulfuric acid. At that point, enzymes (organic catalysts) can be used to further break down the cellulose into simple sugars, which are then converted (by yeasts) to ethanol and other simple fuels.
In other words, a lot of biochemistry.