Among many others, the famous ecologist James Lovelock defended biochar carbon sequestration. He published in his recent book that we have to turn agricultural wastes into charcoal and bury it. This is how Gaia would remove excess CO2 from the atmosphere.
To rename charcoal as biochar is criticized by both authors, but the current debate justifies the name biochar. Biochar should be distinguished from charcoal, which is produced to be used as a fuel. Those images are presented by Biofuelwatch. Neither charcoal produced for the industry nor charcoal produced in Virunga National Park (threatening the last Mountain Gorillas) will establish a carbon sink. Carbonizing biomass which would otherwise decompose or would be burned and its use as soil amendment, this is biochar. Carbonizing rainforest will not create a carbon sink. The carbon trade and biochar carbon sequestration could enable farmers to invest into long-term soil fertility and reduce deforestation. The utilization of waste biomass would actually mitigate those concerns associated with bio-fuel production.