Bill Gates-backed Graphyte is scaling up its carbon casting process to make solid blocks from waste plant material.
A new company called Graphyte says it has developed a startlingly simple and inexpensive process it calls carbon casting to remove carbon dioxide from the atmosphere. The startup, incubated by Bill Gates’ Breakthrough Energy Ventures, revealed a process for turning plant waste into carbon-storing blocks that can be buried underground for thousands of years. Carbon casting costs around $100 per ton of CO2 removed, a long sought-after milestone for affordable carbon removal technology. If Graphyte can scale up effectively, its natural method of capturing and storing carbon could play a pivotal role in reaching global net zero emissions.
Graphyte’s carbon casting process compresses plant matter like wood chips and rice hulls into solid blocks, wrapping them in an impermeable barrier before burial underground. The dried, compressed plant waste contains stable carbon extracted from the atmosphere by natural photosynthesis. Devoid of microbes that cause decomposition, the blocks can remain intact for centuries without releasing their stored CO2. This is a reverse-extraction of sorts, interring carbon underground rather than exhuming fossil fuels.
Carbon removal is considered essential to supplement emissions reductions and decarbonize the global economy. Projections by the UN’s Intergovernmental Panel on Climate Change consistently show the need to remove 5-10 gigatons of CO2 yearly by mid-century, around 12-25% of current emissions. Some sectors like aviation, steel and cement are extremely difficult to fully decarbonize with renewable energy. Most scenarios limiting warming to 1.5°C involve massive scaling of carbon removal alongside rapid emissions cuts.
“We’ve bet the future of our planet on our ability to remove CO2 from the air,” Chris Rivest, a partner at Breakthrough Energy Ventures told the Washington Post. The investment firm was started by Bill Gates and a coalition of private investors to fund transformational energy breakthroughs. Rightly so, Gates has been outspoken about carbon removal technology’s critical importance in addressing climate change.
At $100 per ton, Graphyte’s carbon casting approach reaches a cost target that could enable the large-scale carbon storage required. Direct air capture, which uses giant machines to separate CO2 from ambient air, costs $600-$1200 per ton. Startups working on direct air capture, like Carbon Engineering and Climeworks, have raised hundreds of millions in investment, but costs remain prohibitive. Biomass for energy production with carbon capture at $100-$200 per ton is more affordable but relies on unsustainable biomass supplies that preclude scaling beyond hundreds of millions of tons per year.
Graphyte’s carbon casting feedstock is waste plant matter diverted from decomposition, avoiding competition with food production or land use. The company plans to source raw materials from timber and agricultural operations that generate millions of tons of unused biomass yearly. The carbon casting process condenses the plant matter into 50 times its original density, easing transportation and underground storage requirements. The lack of complex engineering is also an advantage over costlier methods as it means the process may be deployed in developing nations where much of the biomass originates.
Graphyte plans to build its first commercial-scale carbon casting plant in Pine Bluff, Arkansas, capable of removing 250,000 tons of CO2 annually. The company aims to sequester millions of tons per year in distributed plants nationwide. Graphyte will need to prove the scalability of its sourcing, logistics, and underground storage operations. Responsible monitoring and accounting of buried carbon is also essential to ensure permanence.
Still, the potential is enormous if Graphyte succeeds in deploying its natural carbon casting carbon removal solution. With adequate investment and execution, its inexpensive recycled carbon blocks could substantially impact carbon neutrality. Gates and his fellow investors are betting on the transformative power of innovation to address climate change. If this ingeniously simple idea pays off, it could set an example of how human creativity and natural systems can work together to repair and regenerate the planet.