From “unconventional” methane production and recovery to biological mitigation options: A literature review relying on text-mining tools
This report aims to address climate change by focusing on methane (CH4), a greenhouse gas with high global warming potential. Methane is the second most important greenhouse gas in terms of concentration and impact on the climate. This highlights the importance of focusing on processes that are able to lower the methane concentration in the atmosphere, where it is considered a significant contributor to climate change. This can be achieved by (a combination of) emissions avoidance, recovery, mitigation, capture and combustion or use.
This review, in itself, is also significant in terms of scientific process. The narrow literature review allowed for the (manual) definition of a mapping structure. By using text-mining tools, this structure can now be applied to a broader set of scientific documents. Such scaling up will enrich the mapping and help to enhance the mapping structure. This enhanced knowledge gathering will in turn lead to better mapping of ongoing activities and thus mapping of the gaps within.
The review analysed 109 scientific communications, mapped along various dimensions:
— by type of document: 17 documents reviewed specific aspects of methane;
— by environment (e.g. atmosphere, soil, freshwater and saline water) and by source of methane held in these environments;
— by process: methane production through methanogenesis, methane absorption for separation or for storage, genetic approaches, as well as methanotrophy, methane oxidation and methane conversion;
— by by- and co-products, such as carbonates, chromate, copper, iron, manganese, nitrous compounds (N2O, NOx), ammonia, nitrate, sulfur and sulfate, but also fuels and chemicals, such as lactic acid, methanol and acetate;
— by technologies relying on living organisms and micro-organisms, such as biochar, biotrickling filtration, digesters, microbial fuel cells and relevant genetic technologies (e.g. next-generation sequencing), or relying on ((in)organic) materials such as membranes, sorbents or pressure swing absorption;
— by stage of development: demonstration or commercial projects, patents, estimates of the potential for methane emission reduction, quantified costs, other economic aspects, programmes and partnerships.
The review provides a list of possible technologies and constitutes a step towards finding the most cost-effective approaches to methane emission mitigation. It identifies processes and technologies for the biological oxidation of methane, as well as for methane recovery and controlled biomethane production. However, it also highlights how broad the topic is and the numerous questions that remain. As such, this review calls for additional and more targeted investigations. The most salient investigations are as follows:
— the ongoing efforts to thoroughly identify the spatial/geographical distribution of greenhouse gas sources to better understand the contributions of each greenhouse gas, source and sector to global warming;
the role of microorganisms in methane production and mitigation and the ethics of genetically modifying such natural processes;
— the added value of joint anaerobic oxidation of methane and denitrification processes, leading to both nitrous oxide (N2O) and CH4 consumption, which are powerful greenhouse gases;
— the feasibility of developing the air capture/consumption of greenhouse gases besides and/or coupled to carbon dioxide (CO2).
Technology is an enabler. Should the technological bottlenecks above be removed, the economic, environmental and social benefits could be realised.
MARMIER Alain;
SCHOSGER Jean-Pierre;
2020-12-02
Publications Office of the European Union
JRC121995
978-92-76-22969-8 (online),
1831-9424 (online),
EUR 30392 EN,
OP KJ-NA-30392-EN-N (online),
https://publications.jrc.ec.europa.eu/repository/handle/JRC121995,
10.2760/09370 (online),
