Biomethane and RNG represent a widely underutilized energy resource in NA. The ample supply of organic feedstocks from food waste, wastewater solids, agricultural biomass and municipal waste solids has historically been ignored, mainly because of the inexpensive and plentiful supply of fossil fuels. As attention has turned to GHG reduction and demand for renewable energy has grown, the popularity of RNG projects has spiked sharply in NA over the past decade, growing from 53 operational projects in 2014 to over 334 in 2024.
There are currently 165 projects under construction, with plans for another 322. RNG offers numerous environmental, economic and energy benefits, particularly as incentives have increased. RNG is regulated at both the state and federal levels to support decarbonization efforts and prevent harmful constituents from reaching the atmosphere. There are many programs at the state and federal levels that allow RNG producers to sell their products through pathways. Each pathway requires specific measuring protocols as does the RNG end user.
RNG has been a source of lighting and heat since the mid-1800s; it is used to fuel streetlamps across Europe. In the 1930s, microbiology emerged as a leading science, enabling the identification of anaerobic bacteria and the development of conditions for methane production. Currently, this method is also being used to power hydrogen fuel cells, providing backup power to data centers. The mid-2000s saw real growth in RNG as methane upgrading technology improved, allowing producers to meet natural gas pipeline quality standards. By capturing organic wastes for upgrading, RNG offers fuel diversity and availability as biogas sources are generated, continuously allowing for high availability.
RNG projects bolster local economies by creating jobs through infrastructure projects, production and sale of vehicles suited for RNG use and plant operations.
Improved air quality is a secondary benefit of RNG production. Covered digesters trap harmful constituents, preventing them from escaping into the atmosphere and protecting facilities and agricultural personnel from high levels of H2S and bacterial pathogens. It also prevents contamination of waterways and groundwater supplies from animal waste and landfill runoff. When upgraded properly, RNG can achieve a Btu value of 1008 or more.
Federal and local RNG pathways have been developed and are continuing to be adopted at the state and regional levels. EPA’s renewable fuel standard (RFS) program and California’s Low Carbon Fuel Standard/ California Air Resources Board (LCFS/CARB) are the most popular of these. But with regional adoption of carbon reduction pathways, like the Midwest Renewable Energy Tracking System, RNG’s future in the North American energy equation is secure.
Upgrading, or refining, biogas is defined by the application and the intended end use of the gas or fuel. Upgrading biogas consists of separating undesired constituents like CO2, H2S and VOCs from a majority concentration of methane. Biogas consists primarily of methane and CO2, along with high concentrations of H2S and moisture, all of which must be upgraded to acceptable levels. Gas can undergo minimal upgrading, such as reducing moisture, H2S and/or CO2 to power motors for kW production, drive compressors for injection or fuel cells for backup power. Each of these methods fulfills a specific need for state green energy programs, federal and state air quality standards and national fuel standards programs. At this stage, it is still biogas. It becomes RNG only after being upgraded to meet pipeline specifications. It can then either be injected or transported to a pipeline for distribution.
RNG offers multiple avenues through which producers can market methane. The currency used is Renewable Identification Number credits and Renewable Energy Credits. These credits are tangible, tradable currency that represent a qualifying renewable fuel. These credits have played an important role in the development of RNG/biodiesel in North America and are part of the RFS program and LCFS.