An anonymous reader quotes a report from the Washington Post: For decades, scientists have tried to figure out ways to reverse climate change by pulling carbon dioxide out of the atmosphere and storing it underground. They’ve tried using trees, giant machines that suck CO2 out of the sky, complicated ocean methods that involve growing and burying huge quantities of kelp. Companies, researchers and the U.S. government have spent billions of dollars on the research and development of these approaches and yet they remain too expensive to make a substantial dent in carbon emissions. Now, a start-up says it has discovered a deceptively simple way to take CO2 from the atmosphere and store it for thousands of years. It involves making bricks out of smushed pieces of plants. And it could be a game changer for the growing industry working to pull carbon from the air.

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. The approach, the company claims, could store a ton of CO2 for around $100 a ton, a number long considered a milestone for affordably removing carbon dioxide from the air. […] Graphyte’s approach uses the power of plants and trees to photosynthesize and pull carbon dioxide from the air. While trees and plants are excellent at carbon capture, they don’t store that carbon for very long — when a plant burns or decays, its stored carbon comes spilling back out into the air and soil.

Graphyte plans to avoid that decomposition by taking plant waste from timber harvesters and farmers and drying it thoroughly, removing all the microbes that could cause it to decompose and release greenhouse gases. Then, in a process that they call “carbon casting,” it will compress the waste and wrap it into Lego-like bricks, for easier storage about 10 feet underground. The company says that with the right monitoring systems, the blocks can stay there for a thousand years. […] Graphyte is planning to build its first project in Pine Bluff, Ark., and the company hopes to sequester its first carbon for a customer in 2024. It remains to be seen whether Graphyte will be able to scale up its operation to removing millions of tons of CO2 from the atmosphere. The company will need to secure many sources of plant waste and build many small processing centers around the country to be successful. “The simplicity of the Graphyte approach is so exciting,” said Daniel Sanchez, who runs the Carbon Removal Lab at the University of California at Berkeley, and serves as a science adviser for Graphyte. “You don’t need very expensive equipment or processes. And it locks up a lot of the carbon in the wood — nearly all of it.”

“People that are academics probably thought about this before and were like, ‘That’s way too simple,'” Sanchez said, laughing. “‘No one’s ever going to do that.'”