WASHINGTON — While global transportation transitions to a cleaner future fueled by alternative power sources, North American railroads have fewer good options outside of diesel fuel.
“We love diesel; we like to take showers in diesel,” joked Michael Nicoletti, a partner at Innovative Rail Technologies (IRT), at “Toward Zero Emissions in Rail: Lessons Learned,” a panel discussion held at the Transportation Research Board’s 124th annual meeting here.
Nicoletti’s observation underscored a fundamental truth about freight railroading as it’s configured in the United States: No cheap, easily produced substance packs the same power per molecule as the fractional distillate of petroleum fuel oil refined for use in diesel engines.
That’s why an estimated 42,000 locomotives compliant with Federal Railway Administration regulations, and many more non-FRA units, run on diesel.
But, there’s a catch.
Emissions from diesel exhaust produced by locomotives, trucks and ships cause as many as 30,000 premature deaths each year. A decades-long global movement has succeeded in achieving substantial reductions in diesel emissions and given birth to an alternative fuel industry that is taking aim at perhaps the most problematic mode — rail.
“There are virtually no current standards that exist that are directly applicable to zero-emissions (ZE) equipment on rail,” said Marcin Taraskiewicz, rail and transit vehicle technology lead for HDR. While standards do exist for other applications of ZE energy sources for other industries, he said those standards aren’t always fully, or even partly, applicable for rail use.
Rail standards are still years away, Taraskiewicz said, and as the technology matures as-yet-unforeseen requirements may need to be defined in the future. No current regulations exist to govern the design and use of ZE equipment; such regulations tend to be rooted in past experience that in and of itself is lacking due to the absence of its use in significant numbers. Those difficulties are compounded since regulations lean on relevant standards, which still don’t exist for the technology.
Taraskiewicz said risk analysis is the main path forward to gain regulatory approval to operate ZE equipment.
Few manufacturers produce equipment such as batteries, fuel cells and hydrogen tanks for use in rail. Components are typically repurposed from marine, automotive or industrial applications for rail use. Testing and validation are required to demonstrate the suitability of these components in the rail environment covering shock and vibration, temperature extremes, duty cycles, and fire safety.
The choice of ready-to-run power is limited, confined mainly to multiple unit (MU) passenger trains and short range/yard locomotives. Major European builders Siemens, Stadler, Alstom, CAF and Talgo offer or are developing ZE MUs. Taraskiewicz said conversion of existing equipment to zero emission is an option, and that several operators have projects that are in the planning stages or fully underway. But with little operating experience with ZE on rail, the definition of requirements often falls on the operator.
“Operators are pursuing alternative fuels near zero emissions for long-range/heavy-haul fleets,” said Taraskiewicz, “but they don’t have the needed energy-to-weight power ratios. Cleaner diesel fuels are being looked at. Diesel is a high-energy fuel.”
Taraskiewicz said hydrogen and compressed natural gas are being worked on, but with no standards, development is slow. “Cryogenic compressed hydrogen is another option. Alternative fuels is an ever-developing field that is moving the goal posts for technology. It could take 10-15 years as standards try to catch up. Like everything else, it’s going to take some time.”
Development of standards and regulations will continue, said Taraskiewicz, equipment for rail-specific designs will evolve, and power sources of increased efficiency and energy density are expected as the technology matures and other energy sources, such as ammonia, which is hydrogen-dense, emerge as viable alternatives over the next 10 years. He said battery power for some locomotives is available for medium-distance runs of 200 miles round trip, “but anything beyond that, you’re doing diesel.”
To that end, Nicoletti said IRT is testing lithium-ion batteries in rail.
“Specific customers have specific needs,” he said. “Let the technology flourish where it does first, then emanate across the industry.”
IRT’s current product placement ranges from 1,200-horsepower locomotives for Cando Rail Services in Edmonton, Canada, to 3,000-horsepower units for the U.S. Army and Grand Canyon Railway.
Battery power has been proven in the automotive sector.
“Have you been in a Tesla? Have you felt the torque?” Nicoletti asked. “That power is on tap to give basic explanations as to how the technology works.”
He said better outreach is needed from government agencies.
“If you listen to railroad discussions, no one really knows which direction to go. They are waiting to be told which way to go. But the reality is, for a variety of reasons, I don’t expect to see a lot of this tech on the rails in my lifetime.”
The process of concurrence by the FRA, he said, protects people from the improper deployment of technology. “But [the process] is a black hole to many people. There needs to be more cooperation, and across agencies, to make it a more approachable and understood process.”
Panelist Lynn Harris, senior subject matter expert with DB E.C.O. North America, said 27 trains in Germany are now operating on hydrogen and looking to expand. His company is working with North American transit agencies and operators, but the struggle is real.
“The fuel and components will reach cost parity with diesel in eight to 15 years,” Harris said. “There are workforce issues in managing the technology. It’s more expensive than stand-alone battery power but less than overhead catenary installation. It’s not a one-size-fits-all solution but ‘hydrail’ has a viable place. It’s an evolving technology, but we don’t want to throw the baby out with the bathwater. There are significant public health benefits in railyard-adjacent communities, and workforce health benefits. There will be more inclination to ‘take the trains.’”
For its part, absent any regulations, the FRA maintains an Alternative Fuels Program to help evaluate risks for power sources other than diesel, or electric via catenary or third rail.
The agency outlined the program in letters to the industry in 2013 and 2018. A 2025 letter “is a work in progress,” said panelist Michael Hunter, executive staff director of the FRA, while observing that the rail sector accounts for a very small segment of emissions.
But for those who may be tempted to experiment, Hunter explained that the agency derives its authority for the program from the Locomotive Inspection Act. “Generally, a locomotive can be used in service only when it is in the proper condition and safe to operate,” he said.
Equipment that falls under the program includes locomotives, as well as MU locomotives, that use an alternative source of energy for power. (Interpreted broadly, a locomotive is defined as a rail vehicle capable of moving other equipment. This is notable given current development of self-propelled freight cars.)
Alternative sources of energy, Hunter said, include hydrogen gas or liquid, a rechargeable battery energy storage system, or technologies that convert other chemicals to fuel. He noted that railroads have in the recent past focused on the use of compressed natural gas and liquefied natural gas.
Hunter showed a slide of the FRA’s risk assessment matrix guiding an evaluation of the hazards and risks associated with the use of alternative fuels.
“The scenario for evaluation must be clearly defined,” he said. “Changes in the ‘use case’ can impact the probability of a hazard occurring. Assumptions and rationale must be documented, and the analysis provided to FRA for approval.”
Because there are no regulations, Hunter offered possible questions for situations that are considered on a case-by-case basis:
- Does modification of a locomotive’s fuel source from diesel to battery mean the locomotive is “remanufactured”? Answer: Maybe.
- Does modification of a locomotive’s fuel source from diesel to battery mean the locomotive has different dynamic characteristics? Answer: Maybe.
Hunter reminded attendees about other FRA safety regulations that may come into play:
- Locomotive electronics, including analysis of fuel source cutoff.
- Structural elements such as brakes and suspension.
- Vehicle/track interaction that may be affected by a changed center of gravity or mass.
- Emergency preparedness.
- System safety/risk reduction.
- Training regulations.
Regulatory compliance items may also weigh on the safety analysis to address identified hazards.
Find more articles by Stuart Chirls here.
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