CAS-CLIMATE: DIRECT METHANE CAPTURE IN AIR BY AEROBIC METHANOTROPHS

University Of Washington, Seattle WA

Investigators

Abstract

Methane has a warming impact 34 times greater than CO2 on a 100-year timescale, and 86 times greater on a 20-year timescale, and its relatively short half-life in the atmosphere (~10 years) provides the opportunity for near-term climate mitigation. This project targets creation of a technology that would set the stage to slow global warming by removing methane from air at significant scale. Removing methane from the atmosphere is challenging due to the low concentration (1.89 ppm). This project focuses on creation of technology to remove methane from the air over sites where emissions result in locally higher concentrations in the air, such as many landfills, sewage treatment plants, coal mines, oil and gas wells, feedlots, and hydroelectric dams, using methane-consuming bacteria (methanotrophs). Many methanotrophs can be stably maintained at 500 ppm methane, making this concentration a possible target for reactor deployment. Tens of thousands of such sites in the United States are projected to contain 500 ppm or more methane in the overlying air, providing the opportunity to achieve atmospheric methane capture at scale. Although biofilter technology exists to remove methane from gaseous waste streams, it is optimized for more concentrated methane and is not practicable at 500 ppm methane. This project aims to result in a laboratory prototype for consuming methane from sites with 500 ppm or greater in the air, with a goal of a 10-fold increase over current capacity (methane consumed/m3 treatment volume/year). The project will start with methanotrophs identified in the Lidstrom lab that have 2- to 4-fold higher rates of methane consumption at 500 ppm than any in the literature, and develop improved strains and optimized growth conditions including consortia. The team will then model, test, and optimize for methane consumption a modified biofilter configuration using optimized microbial communities. Concurrently with experimental work, the team will develop an integrated modeling framework, coupling process simulation with impact assessment, to assess the bioreactor systems under several potential operating scenarios. The team will then conduct linked techno-economic and environmental life cycle assessment studies to illustrate the potential for economic feasibility and environmental benefit for widespread application of the bioreactor systems and guide further research and development work. The experimental and modeling teams will work closely and collaboratively, in an iterative design process to build the final framework and obtain a robust assessment of feasibility. The long term goal is to see these bioreactors as standard equipment at landfills, sewage treatment plants, feedlots, hydroelectric dams, coal mines, and elsewhere. This methane capture would have a powerful impact on the climate future, especially when coupled to parallel efforts to reduce methane emissions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.