|Image courtesy of the European Commission.|
RNG has vast potential across the U.S. The American Gas Foundation estimates that anaerobic digestion together with thermal gasification has the potential to replace 45 percent of the 38 billion gallons of diesel fuel consumed annually across the country. Blended with current conventional natural gas resources, this volume of RNG can contribute to greenhouse gas (GHG) emission reduction targets and fuel security objectives.
Federally, the Environmental Protection Agency’s (EPA) historical focus on air quality impacts from biogas sources provides a foundation of experience for the development of RNG infrastructure. Landfills, dairy operations and municipal solid waste streams are the most promising commercial sources of biogas – EPA has long regulated such sources and required recovery and combustion of landfill gas to improve local air quality. Increasingly, these sources are considered prime targets for methane capture and energy for transportation.
Beyond EPA requirements, Renewable Portfolio Standards (RPS) in various states typically encourages waste methane capture for electricity generation. However, without similar transportation policies, much of the RNG potential in the U.S. remains just that: according to Energy Vision, of 541 landfill methane capture systems in place across the U.S., only five use the resulting gas for vehicle fuel, and EPA counts another 501 sites as viable methane capture opportunities. 1,500 waste water facilities recover biogas and another 2,000 are considered ideal candidates, and 186 farms have anaerobic digestion facilities, while a further 6,900 could economically produce renewable gas.
RNG’s potential contribution to environmental and climate goals is shown by California’s Low Carbon Fuel Standard (LCFS) for vehicle fuels. It sets standards for the overall carbon intensity allowed for all fuels sold in the state (a declining share over time) and gives fuel providers flexibility to use a range of alternatives - including conventional natural gas and RNG. Under California’s LCFS, waste feedstocks made up less than 1 percent of biofuel volumes in 2012, yet generated 10 percent of all biofuel credits due to their exceptionally low carbon intensity. In other words, RNG made from wastes – which is nearly all sources currently suitable for transportation – helps fleets and fuel providers achieve tremendous progress toward meeting the standard.
Early adopters of RNG for transportation are often companies who already handle feedstocks and see the benefits of converting waste (which carries a cost) into a fuel that powers their businesses. Examples are:
• Fair Oaks Farms - a dairy producer in Indiana that generates 865 MMBtu or just under 5,900 Diesel Equivalent Gallons of RNG every day from their 11,000 cows, fueling 53 daily deliveries of milk, resulting in $2.5 million annual fuel savings, and GHG emissions reductions of more than 16,500 tonnes.
• The Altamont Landfill in California says it’s the largest RNG for transportation operation in the world, powering nearly 400 garbage trucks with fuel produced from the waste it hauls. Operated by Waste Management, the facility has been recognized by the EPA, the U.S. Department of Energy and the State of California, among others, for their sustainability leadership.
• Similar projects include Rodefeld Landfill in Dane County, Wisconsin, which powers nearly 30 vehicles by waste-derived RNG, and the Janesville Wastewater Plant in Wisconsin, which has produced biogas since 1970 and added a facility in 2011 to bring it to vehicle-quality standards. It plans to power over 40 vehicles by 2022.
These examples of “self-fuelling” systems show the many ways RNG can help firms reduce transport fuel costs, reduce their energy footprint, and make a substantial contribution to climate and environmental goals.
 American Gas Association, “The Potential of Renewable Natural Gas: Biogas Derived from Biomass Feedstocks and Upgraded to Pipeline Quality” (2011).
Environmental Protection Agency, “Landfill Methane Outreach Program” accessible via: http://www.epa.gov/lmop/faq/public.html. Directly venting methane has a more potent climate impact than carbon dioxide (converted through combustion and flaring).
 Energy Vision, “Renewable Natural Gas (RNG): The Solution to a Major Transportation Challenge” (2012).
 Sonia Yeh, “Status Review of California's Low Carbon Fuel Standard Spring 2013 (REVISED VERSION)”, UC Davis Institute of Transportation Studies Research Report (2013).
 1 MMBTU of natural gas = 6.81 Diesel Equivalent Gallons
 Innovation Center for US Dairy, “Case Study: Dairy Power” available at http://www.usdairy.com/Public%20Communication%20Tools/DairyPowerCaseStudy_RenewableEnergy.pdf
 Energy Vision (2012).
 Waste Management, “Altamont Landfill”: http://altamontlandfill.wm.com/index.jsp
 Energy Vision (2012).