During a recent round-table session I attended with British scientist and Gaia author James Lovelock, it was easy to walk away feeling helpless about the climate problems humanity faces. But when pressed, Lovelock said he does believe there’s potential in “biochar” — that is, converting some of the world’s biomass (e.g. forest slash, agricultural residues, fast-growing grasses grown on depleted soils, farmed algae) into charcoal and sequestering the black mass in soil or under the ocean. This is done through a process called pyrolysis, which when creating the charcoal locks in about 60 per cent of the biomass’s carbon. Charcoal stays inert and chemically stable for hundreds of years. Best to turn some of the world’s biomass into charcoal instead of letting the biomass rot and release methane into the atmosphere. At least that’s the thinking.
In the end, it’s the rough equivalent of making coal, but doing it in a few hours instead of a million or so years. It’s considered better — and likely cheaper — than the capture and sequestering of fossil-fuel CO2 emissions because it doesn’t just avoid the release of emissions; so-called charcoal sequestration can lead to the extraction of CO2 from the atmosphere. This makes it carbon negative. Turning some of the biomass into charcoal prevents new emissions, but the new generation of biomass that grows also absorbs CO2 from the atmosphere. Over time, the cycle of charring biomass and growing new biomass can act like a big global carbon vacuum.
The trick is doing it on a large enough scale to matter. EnCana researcher Subodh Gupta, a big believer in charcoal sequestration, recently argued at the Canadian International Petroleum Conference in Calgary that the best way to demonstrate that the approach works is to start with the organics and even some plastics collected from municipal solid waste. It solves many problems. Continue reading Creating a carbon vacuum: turn MSW into charcoal and bury it