Techno-Economic Assessment for Methane Mitigation through Catalytic Oxidation from Low-Concentration Sources

Mitigating methane emissions is crucial to achieving climate targets by limiting the temperature rise by the end of the century. This study presents techno-economic estimates for methane mitigation from low-concentration sources by two catalytic routes: thermal and photocatalytic oxidation. Methane mitigation costs for inlet concentrations representative of ambient air (2 ppm), waste stream from an air separation unit (4 ppm), air close to wetlands (40 ppm), ventilation stables (300 ppmhighest reported concentration in the literature for stables), and manure storage (1 vol %) are reported. Mitigation costs (using GWP100:28) are inversely proportional to the inlet methane concentration and range between 52 and 186,000 $/t-CO₂eq in the thermal route and 48-239,000 $/t-CO₂eq in the photocatalytic route for the concentration ranges in this study. We studied the effect of different process-level characteristics on methane mitigation costs. Among other process characteristics, cheap moisture-resistant catalysts and cheap electricity can bring down the costs in the thermocatalytic route, while the availability of sunlight and higher catalytic activity are necessary for photocatalytic routes. Emissions related to electricity use will result in higher methane mitigation costs. Since methane is a short-lived gas in the atmosphere and gets converted to CO₂, the assumption around the time frame for global warming potential will also affect the mitigation costs if the costs are reported per t-CO₂eq mitigated.