Rail technology provider Wabtec (NYSE: WAB) and scientists with the U.S. Department of Energy’s Oak Ridge National Laboratory and the Argonne National Laboratory are working together to develop a hybrid locomotive engine that can run on both hydrogen and diesel.
The project, which has been underway since November, will run for four years and consist of two phases. Phase one will be development of the hybrid engine and phase two will create new hardware that would serve as the next generation of locomotive engines to be gradually introduced into the marketplace.
What’s unique about the program is that it builds upon DOE’s existing research on running hydrogen in combustion engines for light-duty and heavy-duty cars and trucks. However, DOE is starting to shift its focus to include non-road sectors, such as vehicles used in rail and marine transport, according to Josh Pihl, group leader for applied catalysis and emissions control research at Oak Ridge, located in Tennessee.
The timing for the project was also fortuitous for the parties involved since DOE was seeking to shift its research focus and Wabtec to find a home for a single-cylinder engine that had been part of GE Locomotives’ research and development center. Oak Ridge reached out to Wabtec in June 2021 about housing the engine at the national laboratory.
“The big benefit of hydrogen locomotives is that they potentially reduce carbon dioxide emissions,” Pihl told FreightWaves. “So the Biden administration is very focused on trying to minimize greenhouse gas emissions from the entire energy economy of the United States.”
Oak Ridge estimates the North American locomotive fleet emits approximately 87.6 billion pounds of carbon dioxide annually.
“Right now, all of the locomotives that are out there are running on diesel fuel,” Pohl said. “They’re pumping out lots of CO2. And so hydrogen would be a way to continue to run those locomotives but not have CO2 emissions [because] when you burn hydrogen, all it makes us water.”
The two phases of the project
The project will seek to displace diesel fuel by about 50% to 60% with hydrogen in order to create a retrofit option for existing locomotives, according to Dean Edwards, research and development lead at Oak Ridge. Future research could include replacing diesel with renewable diesel or biodiesel to reduce emissions even further, Edwards said.
“[Locomotives] have a lifespan of 30 years or more,” he said. “So, introducing new [hybrid] technologies and new hardware into the existing fleet takes a long time. If we want to have an immediate impact on the carbon emissions, we need to have something that we can implement [for] all the existing fleet rather than wait for the large turnover.”
To get ready for the first phase of the project, Oak Ridge scientists worked to assemble all the support equipment the locomotive engine would need: air supply, coolant, water and peripheral systems, according to Edwards.
“It’s a single-cylinder engine, so it’s not a full engine that would be on the locomotive,” he said. “It’s a research setup. It’s a full-scale, full-sized system, but it doesn’t have a lot of the support equipment that you would have on the actual locomotive built in. So, we’re having to pull in and upgrade all of the sides [since the lab was set up for light-duty vehicles].”
One of the benefits of this stage is the research is using one cylinder off of a locomotive engine model already in use. Figuring out what production hardware will be needed for retrofits “should translate pretty directly” since there are supply chains and materials already in place to manufacture these engines, Pihl said.
But phase two is “where a lot of the challenges are going to be,” Edwards said.
Phase two will involve developing new hardware for the next generation of engines that would be gradually introduced into the marketplace. This stage involves finding ways to completely displace diesel fuel with hydrogen.
This is where Argonne, located in Washington, comes in. It will develop computer simulations to help guide some of the hardware design and the experiments Oak Ridge will be working on, Pihl said. Oak Ridge will then feed the data back to Argonne so it can improve the simulations. The process will entail going through a cycle of improved experiments and models in order to refine results.
A November news release describes Argonne as developing a modeling framework to study combustion and emissions control technologies used in hydrogen engines since it is the combustion process that drives engine efficiency and reduces emissions. Scientists will also be developing simulation software to predict the behavior of combustion engines when operating conditions change and modifications to hardware are made.
Wabtec has a separate research and development agreement with Argonne for the second phase. Software developer Convergent Science is also part of that agreement.
Although Wabtec provides some of the funding for the project, there are other contributors as well. The program is also receiving money from the Vehicle Technologies Office under DOE’s Office of Energy Efficiency and Renewable Energy.
What’s next after the project
There are other challenges associated with the research project. One is the potential for increased nitrogen oxide (NOx) emissions. Since hydrogen burns hot amid high-temperature combustion, that can cause an increase in thermal NOx emissions, “and that can be a problem,” Edwards said.
“[Hydrogen] can have higher NOx emissions than conventional diesel,” he said. “So that’s another thing we want to keep watch on and figure out how we can, again, through dilution or through other approaches, keep those temperatures low enough so that we’re not offsetting carbon losses with ridiculously high nitrogen oxide emissions as well.”
The other issue Oak Ridge scientists and others may have to work through is how to introduce the hydrogen into the engine and make sure it’s well mixed.
“Hydrogen burns very quickly, so one of the things we don’t want to happen is engine knock where it starts burning before you’re ready for it to burn because that can damage the engine or just give you non-optimal performance,” Edwards said. “We want to avoid that.”
Once scientists have finished their work, it will be up to Wabtec to create a product, advertise it and put it out into the marketplace, Edwards said.
Although Wabtec will have access to the intellectual property, all parties are committed to publishing the research to share it broadly with the community of rail engine builders and engine builders, Pihl said.
“One of the things that excites me about this particular project is … the things that [Edwards] learns … are going to be very applicable to other engines as well,” Pihl said. “People are also talking about hydrogen internal combustion engines for on-road trucks, for example. And I think some of the challenges — and there are challenges of running hydrogen in an internal combustion engine — are going to be fairly common across different engine platforms. And so what [Edwards] learns in terms of ‘how do you make that work’ can be applied to other engines.”
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