This is a good PowerPoint by Lee Enterprises experts, Dr. Hugh McLaughlin and Dr. Gerald Kutney, about the status of biochar at the end of 2018.  It talks about what biochar really is, biochar applications and markets, torrefaction, steam thermal, slow and fast pyrolysis, hydrothermal liquefaction (HTL), hydrothermal carbonization, biomass gasification, and the history and future of biochar.