Southern California Gas Co. (SoCalGas) has filed a stakeholders agreement with state regulators calling for the Sempra Energy utility to begin a broad-based program to buy renewable natural gas (RNG) for eventual sale to homes and small businesses.

It is the latest in a series of moves by the nation’s largest gas distribution company to decarbonize its system and comply with a state law calling for specific biomethane targets. Last year, SoCalGas set a 20% target by 2030 for the amount of RNG to replace traditional natural gas.

In its filing to the California Public Utilities Commission (CPUC) Friday, SoCalGas and a variety of stakeholders outlined a proposed plan for offering RNG to residential and small commercial/industrial customers. The stakeholders include consumer advocate groups, including the CPUC independent consumer advocacy unit, national environmental groups and industrial organizations.

Under terms of the proposal, millions of California energy consumers would have the option of purchasing a portion of their needs from RNG, the byproduct of landfill gas, wastewater treatment plants, household waste, grass clippings and farm animal waste.

“The program is expected to create increased demand for RNG, increasing supply and lowering its cost over time, similar to what has happened with renewable electricity from solar and wind,” said SoCalGas spokesperson Melissa Bailey.

In the last four years, SoCalGas and other gas distributors around the nation have sought more RNG for their distribution systems and for alternative fuel vehicles. In California a 2016 law calling for substantial methane emissions reductions sparked greater interest in RNG and decarbonizing the state’s gas delivery network.

With goals of 5% RNG penetration by 2022 and 20% by 2030, the SoCalGas pending RNG tariff request is one of the steps to achieving those goals. In addition, legislation is being pursued that would require the CPUC to establish an RNG procurement program similar to a bill passed last year by the Oregon legislature.

In other news, a report by NGVAmerica and the Coalition for RNG concluded that 39% of on-road fuel used in natural gas vehicles last year was RNG. For the past five years, RNG use in transportation has increased 291%. Last year, 717 million gallons of gasoline gallon equivalent (GGE) of natural gas was used for transportation, including 277 million GGE that was renewable.