Open AccessComparative Life Cycle Evaluation of the Global Warming Potential (GWP) Impacts of Renewable Natural Gas Production Pathways
Author(s) -
Srijana Rai,
Danny Hage,
James Littlefield,
Gabrielle Yanai,
Timothy J Skone
Publication year - 2022
Publication title -
environmental science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.851
H-Index - 397
eISSN - 1520-5851
pISSN - 0013-936X
DOI - 10.1021/acs.est.2c00093
Subject(s) - life cycle assessment , natural gas , environmental science , global warming potential , compressed natural gas , renewable energy , greenhouse gas , global warming , manure , production (economics) , fossil fuel , anaerobic digestion , biochemical engineering , environmental engineering , waste management , engineering , climate change , biology , ecology , methane , economics , mechanical engineering , macroeconomics
Renewable natural gas (RNG) sources are being considered in future energy strategy discussions as potential replacements for fossil natural gas (FNG). While today's supply of RNG resources is insufficient to meet U.S. demands, there is significant interest in its viability to supplement and decarbonize the natural gas supply. However, the studies compare the life cycle global warming potential (GWP) of various RNG production pathways are lacking and focus mostly on a singular pathway. This effort is an attempt to close this gap and provide a comparison between the life cycle GWP of three major RNG pathways and the FNG pathway. The three RNG pathways evaluated are anaerobic digestion (AD), thermal gasification (TG), and power-to-gas (P2G) using various feedstocks. The functional unit is 1 MJ of compressed RNG ready for injection into the natural gas transmission network. The results show that RNG production is not always carbon neutral or negative. Depending on the pathway, the GWP impact of RNG production can range from -229 to 27 g CO 2 e/MJ compressed RNG, with AD of animal manure and AD of municipal solid waste being the least and the most impactful pathways, respectively, compared to the 10.1 g CO 2 e/MJ impact for compressed FNG.