Biochar
17 March 2009I heard a radio segment yesterday morning about something called biochar.
Biochar is what’s left behind when you subject biomass to a process called pyrolysis. That sounds pretty high-tech, but in fact it’s simply what happens when you cook food. If you cook plant or animal material enough, you end up with charcoal-like carbon stuff.
Biochar is getting a lot of attention now because some scientists are promoting its use to help slow climate change. Part of man-made climate change is due to the burning of fossil fuels and the release of large amounts of CO2 into the atmosphere. The plan:
- Trees – like most plants – absorb CO2
- Cut down the trees
- Subject the trees to pyrolysis (that is, cook them, possibly using microwaves rather than burning them) to turn them to biochar, which retains much of the CO2 in them
- Bury the biochar underground. Poof: you’ve removed CO2 from the atmosphere for hundreds or thousands of years, and enriched the soil
- Plant more trees
- Repeat as necessary
This Independent article from last year indicates that biochar has been produced and used for a long time.
More information at the International Biochar Initiative.
Not all charcoal is biochar. True biochar is the result of heating biomass in an emission free pyrolysis reactor devoid of oxygen. Biochar has been shown to be a very effective soil amendment in numerous studies in South America and Japan. It is becoming popularized enough in the US that Biochar Xtra is now even being sold on Ebay. Others are using the bio-oils derived from biochar production to replace fossil fuels. Some folks are alarmed at the possibility of vast tracts of land being denuded to produce biochar. This is not a valid concern because, due to its very low density of from 20 to 35 pounds per cubic foot, the transport of biochar over long distances is not economically feasible.