I have had trouble until recently finding information that strikes me as reliable.
So thanks to PDA for this link from the COP15, a presentation by Sohi and Shackley of the UK Biochar Research Centre entitled Biochar: carbon
Also thanks to Dano for this link to a very credible company called CoolPlanet:
Cool Planet is a technology company that is developing sustainable products to address three of the world’s largest markets: energy, food and water. Currently we are commercializing a technology to create green fuels and biochar in a way that can change the world for good.
Our green fuels are chemically identical to fossil fuels and can be blended into the current fuel supply to reduce greenhouse gases from the air without sacrificing performance or increasing prices at the pump.
Our biochar products sequester carbon and deliver transformative benefits to industries as diverse as agriculture, chemicals and pharmaceuticals.
Our technology allows us to build smaller, significantly less expensive facilities closer to biomass feedstock, so we can expand rapidly, achieve lower scale-up risk and continuously innovate and improve with each distributed facility.
Our strategic investors include BP, Google Ventures, Energy Technology Ventures (GE, ConocoPhillips, NRG Energy), and the Constellation division of Exelon.