Researchers at the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) say they’ve created what could be the most affordable carbon capture system to date.
The new process takes flue gas from power plants, using a solvent to strip out CO2, then converts that CO2 into methanol, which is useful as a fuel, solvent and as an ingredient in plastics, paint, construction materials and car parts.
Water-rich solvents must be boiled at high temperatures to remove CO2 and then cooled before they can be reused, driving up costs. In its approach, PNNL designed solvents that contain less than 5% water, reducing the energy required to release the captured carbon dioxide by boiling.
Researchers say the process uses 17% less energy to accomplish the same task as commercial counterparts. That translates to a 19% reduction in capture cost—as low as $38 per metric ton.
Commercial systems soak up carbon from flue gas at roughly $46 per metric ton of CO2, according to a DOE analysis.
PNNL scientists said they believe the resulting methanol, one of the world’s most widely used chemicals, would incentivize large industrial emitters to capture and repurpose their carbon. In addition to methanol, the team can convert CO2 into formate, methane and other substances.
PNNL chemist David Heldebrant likened the system to carbon recycling.
“Instead of extracting oil from the ground to make these chemicals, we’re trying to do it from CO2 captured from the atmosphere or from coal plants, so it can be reconstituted into useful things,” he said.
Heldebrant said deploying this technology will reduce emissions, but it could also help stir the development of other carbon capture technology and establish a market for CO2-containing materials.
The new system is designed to fit into coal, gas or biomass-fired power plants, as well as cement kilns and steel plants.
Carbon capture and storage (CCS) has been identified as a necessary element in mitigating climate change and achieving net zero emissions, especially in sectors that are difficult to decarbonize, like steel and chemical production.
PNNL noted a significant amount of work remains to optimize and scale the technology, and it could be several years before it is ready for commercial deployment.
Creating methanol from carbon dioxide is not new. But the ability to both capture carbon and then convert it into methanol in one continuously flowing system is. The process has traditionally occurred as two distinct steps.
The capture-and-convert process is not CO2-negative. The carbon in methanol is released when burned or sequestered when methanol is converted to substances with longer lifespans.
But Heldebrant said this new development “sets the stage” for the work of keeping carbon bound inside material and out of the atmosphere.
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