Download White Paper: An Assessment: California’s In-State RNG Supply for Transportation 2020-2024

Study spotlights large volumes of carbon-negative renewable natural gas fuel to be produced in California

In the summer of 2019, staff at the California Air Resources Board (ARB) drafted a proposal to disqualify natural gas vehicles (NGVs) from one of the state’s most popular programs promoting the purchase of advanced, clean transportation technology, the Heavy-Duty Vehicle Incentive Program (HVIP). Proponents of increasing the use of near-zero emission NGVs fueled by renewable natural gas (RNG) opposed the modification suggested by the air agency’s staff. After several months of back-and-forth, the parties eventually reached an arrangement. The accommodation limited future HVIP funding to natural gas-fueled heavy-duty vehicles equipped with an 11.9L low NOx engine. The compromise added an additional requirement: in order to qualify for the HVIP funding, the new vehicle must be fueled with RNG produced within the state of California.

At the time that this understanding was reached, neither the ARB nor the NGV/RNG industries had any sense of the supply of California-produced RNG. When this new constraint was placed on future NGVs applying to the HVIP, no one knew how much in-state RNG was being produced in California. Nor was it known when new supplies would be coming online and how much California RNG would be available in the future. The only projections performed on future RNG supply were theoretical. Without better data on the in-state supply of RNG, it is not possible for ARB or the industry to know if HVIP applicants will be able to comply with this new requirement. Moreover, if other authorities try to apply this same constraint to their state and local vehicle incentive programs, the effort would be hampered by the same absence of data. The estimated RNG inventory described in this report attempts to fill this void.