(558c) Direct Methane Capture Via Aerobic Methanotrophs

According to the IPCC’s Sixth Assessment Report (AR6), as of 2019, 18.6% of greenhouse gas emissions were methane, and as reported by the Environmental Protection Agency, in 2021 the three largest sources of methane emissions were natural gas and oil systems (32%), enteric fermentation (27%), and municipal solid waste landfills (14%). The quantity of emissions is important, as methane possesses a warming impact 86 times greater than CO2 on a 20-year timescale, and breaking this methane down into CO2 would provide near-term climate benefits. An example of these benefits, also assessed in AR6, is that reducing methane emissions would limit both peak warming levels and overshoot warming that would occur once peak global temperatures are reached. To combat methane emissions, a novel bioreactor is being developed as a potential short-term mitigation strategy. This bioreactor would be driven by the metabolic processes of methanotroph bacteria; a class of bacterium which survives solely off methane as its carbon and energy source. Microbes are being isolated which can thrive at methane concentrations of ~500 ppm, which is a common ambient methane concentration at sources like oil and gas wells, dairy farms, and landfills. Methane-rich air will be directed into this reactor, and reduced into CO2 and H2O by the bacteria, whose biomass can also be harvested as a potential value-added product. In order to ensure that this technology is adopted widely and confers a large environmental benefit, it is important to evaluate the potential environmental and economic benefits of bioreactor operations under several potential operating scenarios. In this presentation, we will present our current work to model the methane bioreactor system using spreadsheet tools and process simulation software, and evaluate its performance using life cycle assessment (LCA) and techno-economic assessment (TEA) methods. We will illustrate a range of potential system configurations that offer the best combination of environmental performance and economic benefit, and highlight key process assumptions that will warrant further research for the rest of our project.