Many direct-air capture (DAC) technologies employ sorbent materials to remove CO2 from ambient air. These sorbents require periodic thermal regeneration — typically using steam — to release bound CO2. This thermal regeneration step is often the largest cost and energy driver for DAC processes and a key barrier for commercial scaleup.
A new precision-microwave technology simplifies thermal regeneration with the aim of lowering overall costs for DAC. The Lightswing microwave-heating method developed by Aircapture (Berkeley, Calif.; www.aircapture.com) is being applied to the company’s existing materials and DAC adsorption processes. “Most DAC systems use steam as the heat source to release the CO2 from a sorbent. That method works, and it has helped bring DAC to where it is today. But it also means heating more of the system than just the bond you are trying to break. Lightswing uses microwave energy tuned to the specific frequency that breaks the bond between CO2 and the amine sorbent only, releasing the carbon without heating anything else in the system. It replaces the regeneration step only, the actual capture process and chemistry itself doesn’t change,” says Matt Atwood, founder and CEO of Aircapture. Because Lightswing doesn’t heat the full system and directly targets only the CO2-sorbent interaction, the amount of energy required for desorption is significantly reduced, along with the need for supporting equipment.
Source: Aircapture
“There are no other microwave-based DAC processes commercially deployed today. Microwave-assisted separations have been studied in other contexts, but applying microwave regeneration inside DAC architecture is what makes Lightswing novel. Aircapture holds patents on the approach. We’re now scaling the technology up to first-of-a-kind commercial scale,” observes Atwood.
The company is currently developing a first-of-a-kind 100-ton/yr demonstration-scale deployment in Kenya as part of its selection for Tencent’s CarbonX 2.0 program. “Kenya’s Rift Valley basalt basin provides the geology needed for CO2 mineralization, making it a strong site to validate Lightswing in connection with permanent storage,” explains Atwood. He also notes that the company is leveraging Lightswing as an internal upgrade to Aircapture’s modular DAC platform for on-site CO2 production. “The goal is not to redesign DAC from the ground up. It is to replace the most energy-intensive part of the process with a more targeted regeneration method inside existing DAC architecture.”