A NUMBER OF scientists and academics are sounding the alarm about California’s plans to implement passenger rail trains that are powered by hydrogen — an ostensibly green technology that would replace old school diesel on certain railways but which critics say is still dirty, expensive and risky compared with the other ecological alternative, wire-based electrification.
Such opposition is noteworthy, in part, because hydrogen is often thought of as a potential savior on the climate change front. Critics say that, while hydrogen is indeed clean in its application as a fuel (its use in locomotion produces only water vapor as a byproduct), methods for harvesting the gas usually involve extracting and burning the same fossil fuels it is meant to replace — or, where greener methods are applied, a needlessly expensive and wasteful process.
“(Hydrogen) has been sold as something that doesn’t cause pollution but that’s not the case,” said Jeffrey Beeman, a retired materials scientist from the Lawrence Berkeley National Laboratory.
Questions about hydrogen’s viability for trains come amid the state’s push to convert thousands of miles of rail lines from diesel power to alternatives that reduce pollution and carbon emissions — which, as a general goal, has been widely applauded. The very first of these projects was the overhead wire-based electrification (a system widely referred to as “catenary”) of the Bay Area’s Caltrain, which debuted in August and does not involve hydrogen power.
Meanwhile, California Department of Transportation officials assert that, one way or another, the project to greenify California’s rail network — the plan is to replace diesel across the entire passenger train system by 2050, with almost a third of the work completed by 2034 — is steadily moving forward despite the Trump Administration’s suspension of federal funding. Caltrans says significant funding is already secured from a combination of previous federal grants plus state and private financing, and that the state sees potential paths to obtain the remainder — the anticipated total cost is $307 billion — whether the federal government continues to contribute or not.
According to Caltrans, California has already designated 440 miles of existing and planned passenger rail lines for catenary but is still deciding between catenary and hydrogen for another roughly 1,000 miles of passenger trains. California has in fact purchased 10 hydrogen train sets so far from the Swiss company Stadler Rail, though it is unknown as of yet where they will operate except for one train set that is awaiting its debut in San Bernardino. Caltrans says it is also considering non-hydrogen battery-powered trains but only for certain shorter stretches of track — batteries, by themselves, are generally not considered viable for long distance trains because of the need for frequent charging. Among the planned projects are three that connect to the Bay Area: the extension to San Francisco of Amtrak’s existing line between Emeryville and Sacramento (via the construction of a second transbay tunnel), a new rail line connecting the Dublin/Pleasanton BART station to the San Joaquin Valley and a new high speed rail connecting San Francisco to Los Angeles. Of those three, only the latter is certain to be catenary.
Contractors work on a grade separation project for the California High Speed Rail project in the Central Valley in January 2024. The high-speed trains that will ultimately connect the Bay Area with Los Angeles will rely on electric catenary to power locomotives. “Electrification makes a lot of sense scientifically, but we have to make it pencil out economically,” said Caltrans spokesperson Kyle Simerly. (California High Speed Rail Authority)
“To meet the economic justification for building catenary on a rail line, you need to have enough passenger service running on that corridor to pay it off,” said Caltrans spokesperson Kyle Simerly. “Electrification makes a lot of sense scientifically, but we have to make it pencil out economically. With today’s passenger rail … we’re trying to grow those services but not all of them have the level of ridership today that warrants the overhead costs (of catenary). So we’re looking at other options to get from diesel to zero carbon emissions.”
Installing the overhead wire systems of catenary trains is a much more drawn-out and expensive endeavor than a conversion to hydrogen trains, whose construction requires relatively few extraneous parts, Simerly said. (The Caltrain upgrade, for example, took seven years and cost about $2.4 billion; generally speaking, the installation of catenary can be up to 14 times as expensive as installing the infrastructure required by hydrogen, according to Caltrans). Simerly added that decisions about railway conversion are not Caltrans’ alone to make, but frequently require the consent of various parties including, most notably, the rail companies that own the tracks. These include giants like Union Pacific, BNSF Railway and Amtrak who, even if the funding comes from outside sources, may not have patience in some cases for the longer-term disruptions to service required by a catenary conversion.
Hydrogen’s dirty little secret
Meanwhile, critics of hydrogen-powered trains cite manifold problems.
First is that almost all the hydrogen being produced today involves the use of fossil fuels, or hydrocarbons — via a process where the hydrogen is separated from the carbon and the byproduct of carbon dioxide (and, in many cases, methane — a much more potent greenhouse gas than carbon dioxide) is released into the atmosphere just as it would be, at a different point in the process, if the gas or oil was kept intact and subsequently burned as fuel. Critics say hydrogen power has gained steam owing largely to the lobbying efforts of gas and petroleum companies that would be involved in its extraction.
“I think the issue is misunderstood, and lobbyists are catching something that seems clean and green,” said Brian Yanity, Vice President-South of the Rail Passenger Association of California and Nevada, a rail passenger advocacy group that opposes hydrogen trains. “Many of the politicians supporting hydrogen are not necessarily going to be schooled in clean rail technology.”
Simerly agreed that hydrogen power was a less-than-ideal environmental solution at the moment, but said that California expected to transition to climate-safe solutions within 10 years.
“The vast majority of the hydrogen available on the market today is on the gray end of the hydrogen spectrum, but we expect to have hydrogen that’s green from wheel to well — an entirely carbon-free operation,” he said.
YouTube video
An explainer on how hydrogen fuel is produced and the colors in the hydrogen rainbow. (Primerli/YouTube)
However, critics say even alternative methods of production — the most environmentally safe way to obtain hydrogen currently is by separating it from oxygen in distilled water via high voltage electricity generated by solar power — remain inefficient and costly compared with the efficiency of catenary. For starters, the extraction process is often complex and expensive. Second — here it can get a little confusing — hydrogen cannot in fact be burned as fuel on its own, but is rather itself converted into electricity (via a “fuel cell” on the train) for use with an accompanying battery.
“You have to compress it, store it and run it back through the fuel cell when you’re running the train and then it runs to a battery … You’re left with 40 percent of the original (electrical energy) at the absolute best,” Yanity said. “From what we know about physics, all the technological advancements in the world aren’t going to change that — maybe a little bit, but you’re still left with a lot of unnecessary inefficiency and a higher risk that something goes wrong with all these different parts.” By comparison, Yanity said catenary trains use “well over 80 percent” of the sourced electricity, while Beeman put the figure at 90 percent.
Another issue is that the apparatus for converting hydrogen to battery power usually takes up a lot of space that could otherwise be used for passengers (although Simmerly said hydrogen is mainly being considered for passenger trains that have low ridership anyway). Furthermore, the complexity of the apparatus makes it more prone to maintenance issues, Yanity said, adding that most of the world’s modern train systems — including in most of western Europe, China, Japan, Russia and India — are dominated by catenary and that in Germany hydrogen trains were tried out but have been mostly scrapped due to maintenance problems.
“The vast majority of the hydrogen available on the market today is on the gray end of the hydrogen spectrum, but we expect to have hydrogen that’s green from wheel to well — an entirely carbon-free operation.”
Kyle Simerly, Caltrans spokesperson
Finally, some critics of hydrogen power say that its use on passenger trains and other vehicles is dangerous due to its high flammability and elusiveness against detection (unlike diesel, hydrogen is a clear, odorless gas). However, this point is widely disputed and, where hydrogen trains have operated or been tested around the world, there have been no major incidents, sources said. Proponents of hydrogen trains (and some opponents as well) say that with proper ventilation and leak detection systems the danger is negligible.
A September 2023 letter signed by 29 professors from various University of California schools was sent to Gov. Gavin Newsom expressing concern with the lobbying efforts of The Alliance for Renewable Clean Energy Hydrogen Energy Systems (ARCHES), a consortium of state government officials, UC officials and private companies that is administering the state’s implementation of hydrogen power. The letter does not condemn the use of hydrogen power generally, but it raises concerns that advocates are aggressively pushing the technology without regard to environmental safeguards.
“This could jeopardize carbon cleanliness as well as the reputation of the nascent hydrogen industry,” the letter says.
Hydrogen might not be the best solution
Beeman said California’s interest in hydrogen power could be partly traced back to the Biden Administration’s Inflation Reduction Act, which included billions in financing for states that build hydrogen hubs. (Although California has already received over $4 billion stemming from that legislation for various environmental initiatives that include hydrogen-based transportation, much more potential funding has been frozen under an executive order signed by President Trump in January. Ironically, there is some unintentional overlap between the anti-hydrogen wing of California’s environmental movement and the climate change denialism of Trump — who has referred to Biden’s “Green New Deal” as the “Green New Scam” — in their efforts to curtail the implementation of hydrogen power, even as the two sides have very different motives).
“This is very attractive money (that arrived under the Inflation Reduction Act),” Beeman said. Beeman added that hydrogen could, in some circumstances, have useful applications with other modes of transportation — such as trucks, buses and ferries — where installing overhead wires is not an option (the world’s first ever hydrogen-powered commercial ferry debuted in San Francisco in July of last year). However, even in these cases he expressed tempered enthusiasm.
“Hydrogen might be useful for (reducing urban pollution) — if you run hydrogen on a bus you’re not putting out the kind of nasty pollution that diesel does in a (population center) where people are breathing those particulates,” he said. “But if we’re talking about global warming causes, where catenary isn’t applicable then it should be (non-hydrogen powered) batteries every time.”
Caltrans officials themselves spoke in measured terms about their support for hydrogen trains, calling them a necessary step to speed up the state’s migration away from diesel inside of a complex economic landscape. In a follow-up email to the conversation with Simerly, Caltrans acknowledged that the long term energy costs of hydrogen would be higher than with catenary, but said the upfront investment of time and money made immediately moving to a complete catenary system unfeasible. Furthermore, the agency said that some hydrogen trains could be a stopgap measure in the eventual transition to catenary.
“Hydrogen (trains) can be retrofitted to collect power from an overhead wire if one is constructed in the future,” the email said.
In its updated California State Rail Plan released in January, Caltrans outlined the myriad anticipated benefits of an expanded and modernized rail system.
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An overview of the California State Rail Plan. (Caltrans/YouTube)
One is the mitigated environmental impact of non-diesel trains and the obviation of highway expansion (the report says the plan anticipates almost 200 million daily passenger miles, or 20 percent of total travel, moving from highways to rail neworks). Second is more widespread and equitable access to long range transportation via geographic expansion, better integration of different rail lines, and improved affordability. Third is improved passenger experience overall because of faster service (non-diesel trains, particularly catenary, can accelerate and decelerate much more quickly than diesel ones) and more comfortable accommodations along with various other new amenities. Fourth is improvements in the state’s transportation safety profile, with statistics showing the mortality rate of riding in cars to be 17 times greater than that of trains. And fifth is the economic return on investment, with California expecting savings of $537 billion — stemming from reduced expenditures on highways and reduced costs related to environmental cleanup, among other factors — by the time the whole rail system is completed in 2050 (which would more than offset the estimated $307 billion cost).
For observers like Beeman, the prospect of a modernized train system in California along with an apparently increasing public interest in ridership (in 2024, Amtrak broke its national record with 32.8 million passengers — a 15 percent increase from the previous year), represents an exciting glimpse into the future. He also praised California’s efforts more generally to move toward the use of renewable energy, noting that the state’s energy grid now uses over 50 percent renewable power (solar, wind and geothermal), which places it among the top states in the nation. But he described the hydrogen movement as another pitfall in a society that, even amid the currents of progress, seems perpetually to find new ways of self-sabotage.
“Our short-termism is what causes us to kick the carbon can down the road again and again, and that’s the real problem,” he said. “You’re throwing away most of your energy with hydrogen and, even though it is a short-term solution, if these guys would just spend the money it will be decades and decades of benefits … I’m worried we’ll have this moment 10 years from now of ‘Oh my God, what did we do? And that’s what I’m trying to avert. Why are we dumping billions of dollars for a hydrogen infrastructure project when we have the solutions in our hand? Why not be wise with our solutions? We don’t have much time to solve this.”