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Burying Plant Waste Removes CO2 from the Air. But Can It Scale?

By Maria Gallucci, Canary Media

Startup Graphyte is joining efforts to store biomass underground. Its technique is one of many that aims to use nature’s scraps to help the world decarbonize.

In Arkansas, millions of acres of spindly pines and hardwood trees are logged every year to make plywood, planks and paper, a process that generates plenty of bark, sawdust and other woody waste. Still more land across the state is carpeted by low and grassy rice crops, which leave behind husks and stalks after every harvest.

These scraps of biomass are rich in the carbon dioxide that plants absorb during photosynthesis, presenting an opportunity for those looking to take on climate change. Companies and scientists have dozens of ideas for how nature’s leftovers might help the planet. They can be made into alternative fuels for airplanes and cargo ships to displace petroleum. They can be turned into chemical products, transformed into hydrogen or used to nourish farmland.

The startup Graphyte is doing something else: Burying biomass to trap CO2 deep in the ground.

Last month, the Memphis-based company opened a first-of-a-kind facility at an empty warehouse in Pine Bluff, Arkansas. Graphyte takes waste from nearby rice and timber operations, runs it through a gas-fired drum dryer, then molds the residues into polymer-sealed bricks. The idea is to keep moisture from seeping in, which would cause biomass to decompose and release CO2 — sending the planet-warming gas back into the air.

Graphyte, which is backed by Breakthrough Energy Ventures, plans to store the beige blocks in polyethylene-lined pits, similar to how construction debris is buried in landfills today. The one-year-old company expects state regulators to issue its landfill permit sometime later this spring. Once that’s in hand, Graphyte can begin stashing CO2-rich bricks beneath the fields of southern Arkansas.

Barclay Rogers, the company’s CEO, said Graphyte was born out of the desire to find a more affordable and energy-efficient way of permanently removing CO2 from the atmosphere. Climate scientists agree that at least some carbon removal is necessary to achieve net-zero emissions by 2050. But the current slate of techniques remain unproven, expensive and energy-intensive — potentially limiting their uptake over the coming decades.

“We need technologies that can scale very quickly,” Rogers said in mid-March, speaking from a coffee shop near the company’s facility, which it named Loblolly after the local pine tree species. (He declined for now to share how much the facility cost to build and operate, or how much funding the company has raised to date.)

Rogers said the brick-burying project will remove 15,000 metric tons of CO2 from the atmosphere this year. That’s equal to only 4 percent of the annual emissions from a single U.S. gas-fired power plant. Still, it’s notably more carbon-removal capacity than the largest existing direct air capture projects, including Climeworks​’s Orca plant in Iceland and Heirloom​’s new facility in California, which claim to capture up to 4,000 tons and 1,000 tons of carbon per year, respectively.

Graphyte’s first customer, American Airlines, has agreed to purchase 10,000 metric tons of permanent carbon removal from the Arkansas facility, to be delivered in early 2025.

Read the full article in Canary Media


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