When plants are burned or decay, carbon is released, combining with oxygen to become CO2. But when the same plants are heated in a kiln without oxygen, a process called pyrolysis, about half of that carbon turns into charcoal, a substance so inert it takes hundreds of years to revert to CO2.
Pyrolysis can be performed on an industrial level—a Wisconsin-based company called best Energies sells a device that processes about two tons of wood or other biomass (including turkey waste) an hour—or on a small scale anywhere on earth. The resulting “agrichar” or “biochar” makes a great soil amendment, which means fewer greenhouse-
enhancing fertilizers, and more crops that can be turned into more biochar…It’s the most virtuous of circles.
Added bonus: Pyrolysis produces a gas that can be burned to produce more energy than the pyrolysis itself requires—energy that beats wind or solar in that it’s actually carbon negative. Cornell University’s Johannes Lehmann, a leading expert on the subject, believes the US could convert huge amounts of logging and agricultural leftovers into biochar, and even grow crops just for that purpose. Pyrolysis, he estimates, could eventually offset nearly a third of America’s CO2 emissions.