Over the past few years California has demonstrated remarkable coordination across many areas of state government to develop the market for hydrogen, driven largely by ARCHES, California’s hydrogen hub, a public-private partnership run out of the Governor’s office and funded by Biden-era tax credits. As the Trump administration has shown a remarkable commitment to clawing back money promised to California, and energy demand from data centers and Trump’s war on renewable energy dimming the prospects of affordable green hydrogen, the hydrogen gravy train has hit a road block, but California’s hydrogen hype continues to influence policy. CARB’s now withdrawn locomotive regulation, the In-Use Locomotive Rule, counted fossil fuel-derived hydrogen as “zero emissions”. Despite the new administration in Washington, CARB’s August 2025 report to the governor on zero-emission vehicle deployment continues to recommend investment in hydrogen trains with no mention of other modes, and they continue to hype hydrogen in publications such as the zero-emissions rail dashboard. Finally, CalSTA purchased 10 hydrogen fuel cell trains (with an option to purchase 19 more) at the considerable cost of $21 million each for low-capacity trainsets, with no clear end use. Hydrogen trains are an immature technology with no history in North America and a rather poor track record outside of the US. Hydrogen trains have real environmental and operational disadvantages, threatening service disruptions and the locking in of current anemic levels of service for decades, so what was Caltrans’ justification for this unusual purchase? Little more than colored squares on a chart, with no detailed technical analysis.

Californians for Electric Rail broke down the flaws in Caltrans’ motivated reasoning in a recent whitepaper entitled “Running on Fumes: A Critical Analysis of Caltrans’ ‘Colored Squares’ Justifications for Hydrogen Rail”.

Environmental Comparison

Caltrans bizarrely ranks electrification as worse for the environment than hydrogen, which is an indirect greenhouse gas that easily escapes into the atmosphere, is mostly produced from fossil fuels with similar greenhouse gas impact to diesel, still uses 3 times more energy than electrification even for ‘green’ electrolytic hydrogen, consumes fresh water, and poses considerable safety hazards from leaks and explosions. Hydrogen trains have higher operating costs than catenary trains and are less reliable due to their inherent complexity and status as an emerging technology – thus, they discourage the frequent service we need to provide attractive alternatives to driving. A rail strategy built around hydrogen trains will hold back California’s vehicle miles travelled (VMT) reduction progress – the most impactful way rail can benefit climate. Caltrans’ justification for their ranking? “Visual impacts” from overhead wires. We put together our own chart based on actual data, which shows overhead catenary trains are the clear winner on environmental and operational grounds. Read the whitepaper for citations and calculation information.

Technical/Operational Comparison

Caltrans’ analysis downplays the costs and risks associated with the underdeveloped hydrogen supply chain, while ignoring hydrogen’s inability to meet current capacity or future speed requirements. Caltrans also does not even pay lip service to safety, which is the number one priority for transporting passengers. Hydrogen is considerably more prone to leaks and explosions than natural gas, and hydrogen bus fires are already a problem. Does California’s hydrogen strategy have any plan to deal with the inevitable service disruptions, property damage, or lives lost to these hazards?

Economic

Caltrans’ economic analysis downplays the high cost of hydrogen fuel cell rolling stock (both capital and O&M) and ignores the large capital costs associated with hydrogen refueling and safety infrastructure – which have seen large cost escalations at SBCTA’s first in the nation hydrogen Arrow service between San Bernardino and Redlands, now one year behind schedule. In the long term and at higher levels of service, overhead electrification is the most cost-effective way to power a train. Caltrans’ economic analyses are largely motivated by the $7 billion in federal money awarded to the ARCHES hydrogen hub, which is now in jeopardy due to the Trump Administration. 

Synergistic

Hydrogen trains may be synergistic for the industrial hydrogen industry or Sempra, but not for a rail network. With hundreds of miles of overhead catenary in progress between Caltrain, California High Speed Rail, and Brightline West, overhead electrification is already the dominant zero emissions rail technology in the state. Thankfully the 2024 State Rail Plan recognizes this and calls for 1500 miles of overhead catenary, a major reversal from the 2022 hydrogen strategy critiqued here. Nevertheless, areas of the state rail network where CalSTA’s 10 hydrogen fuel cell trains will be deployed will be disconnected from the wider network for the lifetime of the rolling stock – the opposite of synergy.

Hydrogen Trains in the Real World

Real world experience in Germany shows hydrogen trains have been a failure. The EBV line in Lower Saxony, Germany was the first in the world to run hydrogen trains in service, and saw chronic disruption from mechanical issues as well as shortages in hydrogen fuel. Meanwhile, the RMV line in Hesse near Frankfurt, saw a 19% reduction in service due to mechanical issues with its hydrogen trains, and offered an unprecedented two months in free service in an attempt to regain public trust. Both agencies have had to reintroduce diesel service to replace unreliable hydrogen trains, and are pursuing electrification moving forward. Rail agencies in Bavaria, Baden-Württemberg, and Austria have come to similar conclusions and have selected electrification over hydrogen trains due to cost and reliability issues.

Hydrogen-powered service on the Metrolink/SBCTA Arrow is set to begin this month on September 13th, one year late. The project experienced significant cost overruns and difficulties procuring hydrogen, as chronicled in previous RailPAC publications. Let’s see whether the Arrow follows Germany’s track record of service disruptions and eventual electrification. In the mean time, California would be better off dropping the “colored squares” justification and taking concrete steps to fulfill the State Rail Plan’s call for statewide electrification.