I've been hearing about a new process (maybe not new?) for converting bio-mass to "bio-coal" efficiently.
wikipedia wrote:Hydrothermal carbonization:
HTC is a new variation (biomass conversion) of an old field (biofuel) that has recently been further developed by workers in Germany.[1] It involves moderate temperatures and pressures over an aqueous solution of biomass in a dilute acid for several hours. The resulting matter reportedly captures 100% of the carbon in a "biocoal" powder that could provide feedsource for soil amendment (similar to biochar) and further studies in economic nanomaterial production.
1.^ Maria-Magdalena Titirici, Arne Thomas and Markus Antonietti, New J. Chem., 2007, 31, 787-789. "Back in the black: hydrothermal carbonization of plant material as an efficient chemical process to treat the CO2 problem?"