A Cheap, Low-Tech Solution For Storing Carbon? Researchers Suggest Burying Wood

Researchers propose a "deceptively simple" way to sequester carbon, reports the Washington Post: burying wood underground: Forests are Earth's lungs, sucking up six times more carbon dioxide (CO2) than the amount people pump into the atmosphere every year by burning coal and other fossil fuels. But much of that carbon quickly makes its way back into the air once insects, fungi and bacteria chew through leaves and other plant material. Even wood, the hardiest part of a tree, will succumb within a few decades to these decomposers. What if that decay could be delayed? Under the right conditions, tons of wood could be buried underground in wood vaults, locking in a portion of human-generated CO2 for potentially thousands of years.

While other carbon-capture technologies rely on expensive and energy-intensive machines to extract CO2, the tools for putting wood underground are simple: a tractor and a backhoe.

Finding the right conditions to impede decomposition over millennia is the tough part. To test the idea, [Ning Zeng, a University of Maryland climate scientist] worked with colleagues in Quebec to entomb wood under clay soil on a crop field about 30 miles east of Montreal... But when the scientists went digging in 2013, they uncovered something unexpected: A piece of wood already buried about 6½ feet underground. The craggy, waterlogged piece of eastern red cedar appeared remarkably well preserved. "I remember standing there looking at other people, thinking, 'Do we really need to continue this experiment?'" Zeng recalled. "Because here's the evidence...."

Radiocarbon dating revealed the log to be 3,775 years old, give or take a few decades. Comparing the old chunk of wood to a freshly cut piece of cedar showed the ancient log lost less than 5 percent of its carbon over the millennia. The log was surrounded by stagnant, oxygen-deprived groundwater and covered by an impermeable layer of clay, preventing fungi and insects from consuming the wood. Lignin, a tough material that gives trees their strength, protected the wood's carbohydrates from subterranean bacteria...

The researchers estimate buried wood can sequester up 10 billion tons of CO2 per year, which is more than a quarter of annual global emissions from energy, according to the International Energy Agency.