Want to sequester carbon, create fuel and improve soils in a single step? Then smoulder biomass (such as corn stover or peanut hulls) in the absence of oxygen. The first byproduct is "biochar" (also called "agrichar"), a fertiliser responsible for the rich "terra preta" (black land) soils of the Amazon. The second byproduct is biodiesel, more than enough to fuel the smouldering. And the entire process is carbon negative! The recent International Agrichar Initiative 2007 Conference presented the latest research on this exciting topic. Is this the birth of a new wedge in the fight against global warming?
Update: A quote from the last link, which is the best one to read if you are short on time:
The attendees were clearly excited by this potential, and, unlike other meetings concerned with climate change, an electric buzz of optimism was in the air. Joe Herbertson, director of a consulting company called Crucible Carbon, said, "When I heard about this technology, the hairs went up on the back of my neck. This is the best news on climate change I've ever heard."
One reason for the excitement is agrichar's potential to address a range of problems from poor soil fertility to waste disposal to rural development. About half the world's population relies on charcoal for cooking fuel, and the production of charcoal drives deforestation in Africa and other places. Smoky, inefficient charcoal kilns pollute the air with noxious gases that harm health and heat the planet.
An effort to replace these kilns with modern, efficient pyrolysis units would relieve the pressure on forests by reducing waste and adding the ability to use any source of biomass, including agricultural waste products such as rice hulls. The ultimate objective is to produce enough charcoal to have some left over to bury and increase soil fertility, leading to a bootstrapping effect where increased yields provide both more food and more biomass for energy.