Natural gas is back! Or maybe it never really left. Methane is like that Mason Williams song Classical Gas you just can’t help but like.
The Cummins introduction of a properly designed 15-liter natural gas engine has captured headlines this year. NACFE’s Run On Less – Messy Middle demonstration included no less than three examples of CNG/RNG trucks in impressive duty cycles with Wegmans in New York State, Kleysen Group in Edmonton and UPS in Arizona.
I remember the heady days around 2010 when natural gas was the proposed solution to all of transportation’s problems. It was inexpensive, it was clean, it was readily available, it had stable pricing, it was “made in the USA,” “made in Canada,” and it had infrastructure nearly everywhere. There were two major established companies producing CNG engines — Westport and Cummins. Natural gas was a sure thing.
Until it wasn’t.
Manufacturers struggled to get a few thousand vehicles into fleets. In 2013, Westport stopped taking orders for the 15-liter engines because of lack of demand — having sold only about 1,000 units since its introduction in 2007. In 2014, Cummins also halted development of a 15-liter CNG engine because of market timing uncertainty. The 12-liter and smaller engines were believed to be underpowered and unreliable. Annual natural gas Class 8 freight truck sales volumes hovered between 3,000 and 4,000 units per year from 2013 to 2019 in a heavy-duty truck market that often exceeded 300,000 units per year.
In 2017, Cummins, Daimler, PACCAR, Tesla, Nikola, Volvo and others began talking about battery electric trucks as the future of freight movement. Natural gas became an “also-ran.” The show floors at major conferences, like ACT EXPO, TMC and others, became filled with battery electric concept vehicles. Class 2b through 6 medium-duty vans, box trucks and step vans were being introduced by a herd of upstart new companies and traditional OEMs.
As 2020 arrived, the realities of introducing new battery electric trucks began to set in. Upstarts like Tesla and Nikola each had their own production delays. The traditional OEMs began launching vehicles that would not compete with their bread-and-butter diesels. The industry was assaulted by vested interests across the spectrum pushing their own causes. Companies started to run out of cash. Over the last five years, regulations favoring battery electric trucks over natural gas became more uncertain.
Some visionaries inside Cummins went public in 2021 saying they were working on a new, improved 15- liter natural gas engine specifically designed for heavy-duty trucking. Cummins was covering all the powertrain technology bases in the Messy Middle including developing hydrogen fuel cells and battery electric powertrains. But they understood natural gas was going to have a role in Cummins’ future.
Fleet testing of early pre-production engines began in 2023. Finally, in 2025, Cummins launched production of the X15N. Natural gas was back in freight news headlines.
The timing could not have been more opportune as chainsaws went to work on government agencies and regulations, and “Made In America” became a critical factor in pricing.
So here we are, Cummins has reportedly fixed all the ills that hampered those early natural gas engines. All the promise seen in 2010 has been refreshed now 15 years later. Fleets that abandoned natural gas powered Class 8 trucks are starting to reconsider them. Early experience is showing the new engine can run competitively with the diesels.
Natural gas still has the same challenges it faced in 2010, the primary one is that natural gas trucks are more expensive than their diesel counterparts. This always will be true because of significant differences in the fueling systems. However, cost differences between natural gas and diesel trucks can be mitigated to an extent through incentives, grants and mechanisms like low carbon fuel standard credits.
The infrastructure to support the trucks is still an added expense to fleets. Making a diesel maintenance facility safe for natural gas use can add significant capital costs and on-going maintenance costs.
Availability of natural gas for trucks is good but there still are regions where it is hard to find as seen in the Alternative Fuels Data Center map. That map shows 617 public fast fill stations in the U.S. and Canada capable of fueling Class 8 trucks. Private fueling exists now in many locations to help offset this challenge.
Natural gas pricing may become more volatile as world events place new strains on supply and demand. Renewable natural gas (RNG) supply is growing as reported by the Renewable Natural Gas Coalition, with 536 RNG producing facilities in the U.S. and Canada, with more planned. Safety standards, best practices for fueling and operating, and guidance for first responders are well developed and actively being improved through the guidance of groups like The Transport Project (TTP).
Natural gas trucks also come with their own version of range anxiety for drivers. Where a diesel fuel gauge measures fuel levels in gallons with some minor inaccuracy because of ambient temperature, a natural gas truck measures fuel levels in terms of pressure. Pressure is impacted by temperature in many parts of the fueling system, and the actual energy available to run the vehicle down the road will vary even if the pressure seen on the driver’s gauge is constant. Also, as with all fuel types, empty is never empty. Natural gas trucks have to have some minimum level of pressure — usually 600 psi — to allow safe fueling to start.
Natural gas fueling systems are fundamentally more complex than diesels. They have stricter standards because they cycle between 3600 psi and 600 psi. Where some diesel trucks may have one tank, natural gas trucks may have five or more, each with its plumbing. There are pressure relief systems as well. Natural gas engines also have spark plugs. All those extras add cost versus a diesel. On the plus side, emissions from natural gas trucks are negligible in comparison to the diesel and emission control systems are much simpler.
One wonders where the industry would be if a mature, reliable 15-liter natural gas engine had been available in 2010. Like all technology choices in the Messy Middle, having a place in the future is not guaranteed, but has to be earned. Natural gas is definitely back in the running as a strong option for heavy-duty trucks.
