[Ryan]

Biomass that is lignocellulosic (very fibrous) is still considered difficult to digest conventionally. Some facilities add some of these materials to a digester, but not as the primary feedstock. There are a number of companies/researchers developing processes for breaking down these materials, whether a pre-grinding step, or an additive to breakdown cell walls.
At the moment, the Canadian government promotes these efforts via grants for supporting R&D and ‘next generation’ feedstocks