Trucking fleets operating RNG-fueled trucks save money, slash emissions, and benefit from proven, affordable, clean technology without delay and without compromising existing business operations. RNG is a solution that allows fleets to achieve better than zero results immediately. It is not just carbon reductions that are in play, however. More demanding federal limits on nitrogen oxide emissions and increased durability requirements for new engines make RNG a smart choice for truck operators looking for an alternative to diesel trucks and their increasingly complex emission control systems.
2024 saw the launch of Cummins’ highly anticipated 15L X15N engine, leading a suite of Cummins natural gas engines serving commercial operators. Available now in Peterbilt, Kenworth, and Freightliner chassis, the X15N delivers up to 500 horsepower and torque of up to 1,850 lb-ft, providing a viable workhorse alternative to traditional diesel engines.
Additionally, the Volvo Group’s and Westport Fuel System’s Cespira joint venture is continuing efforts to accelerate the growth of High-Pressure Direct Injection (HPDI) technology into North America. Volvo already uses this technology in Europe for its natural gas internal combustion engine offerings. HPDI technology can run on zero- or carbon-neutral fuels (i.e. hydrogen and biomethane) with diesel-like fuel efficiency, power, and torque.
There are approximately 1,200 heavy-duty natural gas fueling stations in the U.S. While nearly all natural gas motor fuel dispensed in California is RNG, it’s not just California fleets that have access to it. In 2024, 63 percent of RNG motor fuel use occurred outside of California, up from 57 percent in 2023.
The carbon intensity (CI) of renewable natural gas motor fuel continues to drop. Derived from landfills, wastewater, forest waste, food waste, and agricultural waste, RNG continues to make up more and more of the natural gas motor fuel market. In 2023, 79 percent of natural gas used in on-road transportation was RNG, up from 69 percent in 2022. Since RNG is interchangeable with any natural gas vehicle (NGV), RNG is one ultra-low-carbon/carbon-negative fuel that does not require the build-out of new specific infrastructure since it is dispensed from existing stations.
Data from the California Air Resources Board shows the average carbon intensity of the bio-CNG mix sold in California in 2024 dropped to -194 gCO2e/MJ, the lowest CI of any transportation fuel or technology in the state, including electric. That means that fleets operating natural gas vehicles in California are achieving a carbon-negative transportation outcome today.
Cost Effective, Price Predictable RNG
Sourced domestically, natural gas motor fuel is less volatile to global market swings, providing price stability and savings to fleets of all sizes compared to traditional fuels. Toward the end of 2024 the price for natural gas was $0.70 to $0.83 less than diesel in some regions of the country. For fleets with trucks that drive tens of thousands of miles and consume significant gallons of fuel, the price differential results in real savings and helps to offset the higher price of natural gas trucks.
It is also important to highlight that fleets contracting for RNG often see even more savings as they can benefit from economic value associated with renewable identification numbers and in some cases low-carbon fuel credits or clean fuel credits. Under the U.S. EPA’s Renewable Fuel Standard Program, RNG sales generate RINs that can be sold to obligated parties (e.g. fuel marketers and fleet users), sometimes for several dollars per gallon equivalent. For fleets moving to natural gas trucks, ensuring that they are negotiating with fuel suppliers for a portion of the value of RNG credits can be critical to achieving a lower overall total operation of cost and accelerating payback.
Incentives and Regulatory Outlook
Another important financial incentive for NGV fleets has been the $0.50/gallon Alternative Fuel Tax Credit (AFTC). Fleets interested in building their own fueling facilities also benefit from the Alternative Fuel Infrastructure Tax Credit that is now worth $100,000 per qualifying piece of alternative fuel refueling equipment. Of course, changes in Washington are spurring change in energy and tax policy. The outlook for extending incentives that favor natural gas and domestic renewable fuels like RNG is bullish. The Transport Project’s top priority this year is securing passage of the Renewable Natural Gas Incentive Act, which would provide a $1.00/gallon tax credit to end users of natural gas motor fuel derived from renewable sources.
Perhaps more so than any time in the recent past, the regulatory outlook for truck emission requirements is extremely volatile. California’s regulatory future is uncertain. To make increasing emission reduction gains quickly in the commercial space, California regulators should reembrace ultra-low-carbon, near-zero technologies like RNG-fueled trucks. At the federal level, U.S. EPA’s reopening of its Phase 3 HD GHG regulations likely will also support the growth of technologies like RNG.
The Final Word on RNG
NGVs fueled by RNG offer a more cost-effective, less disruptive yet still progressive compliance schedule for commercial fleets of all shapes and sizes. RNG-fueled trucks allow fleets the ability to affordably comply today on their road to achieving full carbon neutrality.
Daniel J. Gage is President of The Transport Project, a national coalition dedicated to the decarbonization of North America’s transportation sector through the increased use of gaseous motor fuels including renewable natural gas and hydrogen.