By capturing and processing the methane emitted from organic sources, renewable natural gas has...

By capturing and processing the methane emitted from organic sources, renewable natural gas has the lowest carbon intensity rating.

Image: Clean Energy

According to recent data from the California Air Resources Board (CARB), the energy weighted carbon intensity (CI) value of California’s natural gas vehicle fuel portfolio in the Low Carbon Fuel Standard (LCFS) program was below zero. 

This first-time accomplishment for the LCFS program means that not only are these vehicles producing zero emissions, the use of renewable natural gas is actually reducing overall emissions even more.

“Given the large and growing volume of heavy-duty natural gas vehicles already hard at work on California’s roads, this is an extremely significant milestone,” said Todd Campbell, chair of the California Natural Gas Vehicle Partnership (CNGVP) and vice president of public policy and regulatory affairs at Clean Energy. “When combined with the fact that most natural gas vehicles recently placed into service are powered by near-zero emission engines, the natural gas vehicle industry is providing the most substantial and cost-effective contributions towards California’s goals to reduce criteria and greenhouse gas emissions while eliminating the use of diesel in favor of renewable, low carbon fuels.”

LCFS is market-based incentive program developed to decrease the carbon intensity of California's transportation fuel and provide a range of low-carbon and renewable fuel alternatives, reducing petroleum dependency and achieving air quality benefits. To calculate the “carbon intensity” of a fuel, all greenhouse gas emissions associated with the entire life cycle of a transportation fuel, including production and consumption, are factored in to the final number.  

By capturing and processing the methane emitted from organic sources including dairy waste, wastewater treatment plants, food and green waste, landfills, and forest management, renewable natural gas (RNG) has the lowest carbon intensity rating of all fuels in the program. Some forms of RNG, such as that produced from dairy waste, can have carbon intensity ratings that are 200-300% lower than even a battery-electric vehicle powered by renewable energy such as solar or wind.

A recently released study further touts the benefits of RNG, forecasting that by January 2024 California-produced RNG for transportation will have an average energy-weighted carbon intensity of -101.74 gCO2e/MJ, generating 3.4 million tons of GHG reductions annually. At that negative carbon intensity, an average natural gas vehicle fueled by California RNG will completely offset the GHG emissions of two diesel trucks. 

RNG can be used as a replacement for conventional natural gas in transportation.

“We are thrilled to see the growing use of low carbon renewable natural gas by our customers in California and across the U.S.,” said Tom Swenson, vice-chair of the California Natural Gas Vehicle Partnership and business development manager for Cummins Inc. “This one-two punch of renewable natural gas in an ultra-clean engine allows fleets to achieve cost-effective carbon negative operations right now in a vehicle that meets their operational requirements.”

Currently, there are more than 175,000 natural gas vehicles in use in the U.S., with near-zero natural gas trucks commercially available from a number of OEMs, including Freightliner, Kenworth, Mack, Peterbilt, and Volvo.

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