The waste sector in California could transition to an all-RNG fleet and cut its petroleum use in half by 2030 by building an on-site anaerobic digestion system at a solid waste management facility in each large town, according to a new white paper from CleanFleets.net and the California Compost Coalition. This would require millions of dollars of funding from the state, which the industry groups call an “appropriate way to incentivize” projects that are otherwise unattractive to private investors.

In Biomethane Transportation Fuel Powering the Solid Waste Industry: Community-Scale Distributed Fuel Production Facilities, the authors describe a closed-loop system in which supply perfectly meets demand. The refuse trucks collect organic waste, the anaerobic digestion system turns the food scraps and yard waste into purified biogas, and then the trucks are refueled with the RNG while parked overnight. According to the paper, this system would best serve a city of 100,000 people that generates 25,000 tons of organic waste each year. With a footprint of less than an acre, the system would easily fit within an existing waste management site.

To ensure that compost materials are clean, the anaerobic digestion system would require the use of refuse trucks dedicated to collecting organic waste. Ideally, two green waste trucks could deliver sufficient waste to produce enough RNG to run seven CNG vehicles using 40 dge each a day.

The investment from California would be significant. To start, the authors are calling on CARB to spend $600 million—$100 million per year for six years—to convert the sector’s remaining 15,000 diesel trucks to CNG. They estimate the capital cost for building more than 250 anaerobic digestion facilities by 2025 to be $4.95 billion. According to the paper, the state could help finance these projects through grant programs, such as the CEC’s AB 118 program; tax-exempt bonds; and other incentive programs.

The authors calculate that 255 anaerobic digestion systems would annually produce 84 million dge of RNG. With its annual demand for transportation fuels at 200 million dge, the waste sector would still need sources of RNG outside its own production facilities.

The California Compost Coalition filed the paper to the CEC docket to “support the new funding of $25 million proposed by the Governor as part of the Cap-and-Trade proceeds for 2016–2017.”