Natural Gas Vehicles for America (NGVAmerica) and the Coalition for Renewable Natural Gas (RNG Coalition) announced that California fleets fueled with bio-CNG achieved carbon negativity last calendar year for the second straight year.

According to data from the California Air Resources Board, 98% of all on-road fuel used in natural gas vehicles in California in 2021 was renewable natural gas (RNG). The annual average carbon intensity score of bio-CNG in that mix was -44.4 gCO2e/MJ, according to the data.

Data from Q1 2022 puts the carbon intensity average of bio-CNG at -61.4 gCO2e/MJ, according to NGVAmerica.

“For the second straight year, California fleets fueled with bio-CNG achieved carbon-negativity in their 2021 transportation operations,” said Dan Gage, NGVAmerica president. “And since 98% of natural gas dispensed in California for use as a motor fuel is from renewable sources, California natural gas vehicle fleets consistently achieve a zero-carbon footprint and virtually eliminate criteria pollutant emissions that contribute to asthma, heart disease, and poor air quality.”

In addition to their negative greenhouse gas emissions, ultra-low NOx medium- and heavy-duty RNG-fueled trucks and buses perform at levels that are 95% below the federal nitrogen oxide (NOx) standard and 98% below the federal particulate matter (PM 2.5) standard.

"RNG facilities address methane emissions from society’s inevitable waste streams, mitigate the environmental impacts of those emissions and convert captured methane into domestic, renewable, clean fuel and energy,” said Johannes Escudero, founder/CEO of RNG Coalition. “These numbers highlight the critical role that RNG is playing in decarbonizing the medium- and heavy-duty transportation sectors today.”

According to NGVAmerica, RNG used as a transportation fuel in California grew 163% over the last five years. NGVAmerica and RNG Coalition report that in 2021 a total of 178.37 million gallons (diesel gallon equivalents) of natural gas were used as motor fuel in the state. Of that, 174.28 million DGE were from renewable sources.

The group also said that data from CARB’s Low Carbon Fuel Standard program confirmed that bio-CNG remains the only net-zero carbon motor fuel in California’s alternative motor fuel portfolio, which includes ethanol, biodiesel, renewable diesel, bio-CNG, bio-LNG, electricity, alternative jet fuel, and hydrogen.