Methane's contribution to radiative forcing is second only to that of CO2. Though previously neglected, methane is now gaining increasing public attention as a GHG. At the recent COP26 in Glasgow, 105 countries signed “the methane pledge” committing to a 30% reduction in emissions from oil and gas by 2030 compared to 2020 levels. Removal methods are complementary to such reduction, as they can deal with other sources of anthropogenic emissions as well as legacy emissions already accumulated in the troposphere. They can also provide future insurance in case biogenic emissions start rising significantly. This article reviews proposed methods for atmospheric methane removal at a climatically significant scale. These methods include enhancement of natural hydroxyl and chlorine sinks, photocatalysis in solar updraft towers, zeolite catalyst in direct air capture devices, and methanotrophic bacteria. Though these are still at an early stage of development, a comparison is provided with some carbon dioxide removal methods in terms of expected costs. The cheapest method is potentially enhancement of the chlorine natural sink, costing as little as $1.6 per ton CO2-eq, but this should be carried out over remote areas to avoid endangering human health. Complementarity with methane emissions reduction is also discussed.
|Journal||Advances in Applied Energy|
|Early online date||26 Jan 2022|
|Publication status||Published - Feb 2022|
Bibliographical note© 2022 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Funding: This research was supported by the National Key Research and Development Plan (Key Special Project of Inter-governmental National Scientific and Technological Innovation Cooperation, Grant No. 2019YFE0197500), National Natural Science Foundation of China (Grant No. 51778511), the European Commission H2020 Marie S Curie Research and Innovation Staff Exchange (RISE) award (Grant No. 871998), Hubei Provincial Natural Science Foundation of China (Grant No.2018CFA029), Key Project of ESI Discipline Development of Wuhan University of Technology (Grant No. 2017001), and the Fundamental Research Funds for the Central Universities (Grant No. 2019IVB082).