Hydrothermal cabonization is an approach to convert almost any kind of biomas into fuel. Biopact has written about hydrothermal carbonization and there's quite a bit about it on the web. Here are some carbonization links that might be useful. Please let me know if you come across any more I'll add them to the bottom of the list... and if you'd like to rank them for me that would be interesting. As would details of the catalyst and an energy balance. Many thanks to David Benson for giving me the idea.
MPG:Coal from Biomass
A Stroke of Genius? A New Recipe for Coal
Back in the black: hydrothermal carbonization of plant material as an efficient chemical process to treat the CO2 problem?
Biomass Refinery for Biomass Town