Graphyte, a new company incubated by Bill Gates’s investment group Breakthrough Energy Ventures, announced Monday that it has created a method for turning bits of wood chips and rice hulls into low-cost, dehydrated chunks of plant matter. Those blocks of carbon-laden plant matter — which look a bit like shoe-box sized Lego blocks — can then be buried deep underground for hundreds of years.
Coal mines in Appalachia fit multiple criteria for this to be effective.
The older ones, sure. Mountaintop removal ones, probably not so much.