Trace methane destruction using microwave plasma effluent

Since pre-industrial times, atmospheric methane concentrations have more than doubled, from 700 to 1900 ppb contributing to ~30% of the current global temperature increase. Capturing atmospheric methane is highly inefficient due to its low concentration, so capture or destruction at the point of origin would be a preferable mitigation strategy.



We experimentally tested the performance of microwave plasma for the destruction of trace methane (< 1 mol %). We evaluated a range of gases in the plasma and injected methane containing air downstream, aiming to use species formed in the plasma to convert methane into species with a lower global warming potential. We use Fourier Transform Infrared Spectroscopy (FTIR) to measure the concentration of methane and other generated products within the effluent of the reactor.

Our current analysis indicates that none of the tested experiments demonstrate lower energy-cost than the already existing methods for the removal of trace methane, with only oxygen showing the potential of becoming as energy-efficient. However, we also demonstrate the simultaneous destruction of trace methane and the production of NO_x, which is of particular interest to agriculture. This process offers opportunities to efficiently produce nitrate fertilizers whilst simultaneously eliminating enteric methane emissions from agriculture. This work underscores the potential synergies between using plasma for environmental remediation and sustainable resource utilization in agriculture.