The Promises and Limits of Biomethane as a Transportation Fuel

The document examines biomethane derived from landfills, wastewater treatment centers, and dairies as a replacement for diesel and natural gas in California's heavy-duty vehicle fleets. While acknowledging its climate benefits over fossil fuels, the authors highlight that California's total biomethane potential from waste would meet only 3% of the state's natural gas demand and 15% of its diesel consumption. The report warns that promoting compressed natural gas (CNG) vehicles could inadvertently increase reliance on fossil natural gas due to this supply gap. It concludes that biomethane provides the greatest emissions reductions when used to generate electricity or hydrogen for electric vehicles, but that battery electric vehicles powered by the grid remain the most effective path for meeting climate goals.

• Biomethane from waste sources in California is insufficient to meet the state's energy demands, potentially covering only 3% of total natural gas demand and 15% of diesel consumption if used exclusively for transport.
• Increasing the adoption of compressed natural gas (CNG) vehicles may risk increasing California's overall consumption of fossil natural gas because biomethane supply is limited.
• Biomethane offers the most significant climate and air quality benefits when used to produce electricity or hydrogen for electric vehicles rather than being used directly in CNG vehicles, due to higher efficiency.
• Battery electric vehicles powered by the current electricity grid outperform low-NOx CNG vehicles fueled by landfill biomethane, providing 30% lower global warming emissions and 20% lower NOx emissions.
• The life cycle emissions benefits of biomethane vary by source; biomethane from dairy manure can result in 'negative' life cycle emissions because it offsets significant uncaptured methane emissions.
• The climate benefits of biomethane can be undermined by methane leaks within the natural gas distribution infrastructure.

APA

Union of Concerned Scientists (2017). The Promises and Limits of Biomethane as a Transportation Fuel. https://www.ucs.org/sites/default/files/attach/2017/05/Promises-and-limits-of-Biomethane-factsheet.pdf

Chicago

Union of Concerned Scientists. The Promises and Limits of Biomethane as a Transportation Fuel. 2017. https://www.ucs.org/sites/default/files/attach/2017/05/Promises-and-limits-of-Biomethane-factsheet.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=The Promises and Limits of Biomethane as a Transportation Fuel |date=May 2017 |url=https://www.ucs.org/sites/default/files/attach/2017/05/Promises-and-limits-of-Biomethane-factsheet.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2017promises, author = {{Union of Concerned Scientists}}, title = {{The Promises and Limits of Biomethane as a Transportation Fuel}}, institution = {Union of Concerned Scientists}, year = {2017}, month = may, url = {https://www.ucs.org/sites/default/files/attach/2017/05/Promises-and-limits-of-Biomethane-factsheet.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }