The Railroad
The Sierra Railroad Company (SRC), established in 1897, is one of California’s oldest operating railroads, with a fleet of 42 locomotives. The company has a remarkable story of innovation in decarbonizing its fleet, as detailed in a previous Reformed Carbon series article. To recap: SRC began exploring alternative fuel sources in response to California’s energy crisis in the early 2000s, when its leadership recognized that locomotives could serve not only as transportation assets but also as mobile generators—a concept they referred to as a “powertrain.”
To power these locomotives sustainably, SRC initially transitioned to biodiesel. Seeking further decarbonization, the company turned to hydrogen production using gasifier technology fueled by bio-derived and waste feedstocks. It acquired the licensing and constructed a plant at Fort Hunter Liggett in Monterey County, California. This facility produces hydrogen via high-temperature gasification, operating at 4,000°F. The FastOx process uses steam and oxygen to break down waste at the molecular level.
To realize its vision, SRC converted a diesel locomotive—Sierra Northern Railway (SERA) 193—into a hydrogen fuel cell-powered unit at its West Sacramento yard. Together, these initiatives present a compelling, self-reliant business case for a localized, vertically integrated hydrogen railroad hub—from feedstock to fuel to fleet.
Locomotive modification: SERA 193 – First-Generation Hydrogen Locomotive
The company’s first-generation hydrogen locomotive, SERA 193, was developed by retrofitting a standard GE RP20BD freight locomotive. Originally powered by three Deutz V8 diesel engines with a combined output of approximately 1,500 horsepower, the unit was transformed into a modular, zero-emission platform. This conversion marked a significant step in Sierra Northern Railway’s effort to modernize rail propulsion using hydrogen fuel cell technology. Rather than relying on an external contractor, the design and engineering of the locomotive were carried out in-house by Sierra Northern Railway, working closely with a network of technical partners and engineers. The SERA project was enabled by a $4M California Energy Commission award in 2021 propping the design, integration, and demonstration of a prototype hydrogen fuel cell switching locomotive. GTI Energy has been a key partner to Sierra Northern Railway on the locomotive projects, leveraging their extensive experience in demonstrating and de-risking transformative technologies. Since the project began, GTI Energy has supported SNR with know-how in hydrogen fueling, safety, industry connections, and more. The success of the collaboration speaks for itself – the first locomotive is running in revenue service in West Sacramento, and work on the next three locomotives is well underway.
The retrofit process involved removing the original hood and prime mover—the large diesel engine and generator that traditionally power the locomotive—leaving behind a long, open deck and the existing operator cab. Importantly, the core structural and safety-critical components were retained, including the wheels (known as “trucks”), the deck, the cab, and the braking systems. These elements are heavily regulated by the U.S. Department of Transportation and the Federal Railroad Administration (FRA). By preserving them, the locomotive maintained its crashworthiness and regulatory compliance, avoiding the need for retesting of core safety systems. The FRA does not require reevaluation for changes related to the propulsion system, allowing innovation to proceed more efficiently.
The cleared platform of the locomotive was outfitted with a series of modular components—including fuel cells, batteries, hydrogen storage tanks, and cooling systems—all designed for straightforward handling, installation, and integration. This modular approach allowed individual systems to be developed and tested independently with partners such as Ballard, who supplied the fuel cells. Once each component was completed, it was craned into place, secured, and connected on-site, streamlining assembly and ensuring system-level flexibility.
The new propulsion system is centered around two 100 kW fuel cell modules provided by Ballard, giving the locomotive a total fuel cell output of 200 kW (about 268 horsepower). This is complemented by a 415 kWh battery pack that supports hybrid propulsion and energy buffering. The combined powerplant performance will have the peak power of about 1500 horsepower. Hydrogen is stored onboard in high-pressure Type IV composite tanks rated for 350 bar (approximately 5,000 psi), with a total hydrogen capacity of 207 kilograms. This modular approach enabled parallel development and simplified maintenance and upgrades. From the outset, the project was closely coordinated with the FRA and relevant safety agencies to address the unique requirements of hydrogen propulsion. The effort was supported by funding from the California Energy Commission and included extensive safety testing and compliance measures.
The locomotive’s weight prior to modification was approximately 260,000 pounds. After conversion, the total loaded weight dropped to around 240,000 pounds. The fuel cell locomotive has turned out to be 20,000 lbs or 8% lighter than its own diesel variant. To manage traction and optimize performance, the locomotive design includes the option to add ballast—either by embedding concrete in the floor or installing steel plates—to increase weight and improve wheel-rail contact. However, this has not been necessary to date, thanks to advanced wheel-slip control technology provided by RailPower. Their computer-controlled traction system enables precise management of wheel slip, allowing even lighter locomotives to effectively pull heavier loads. To strengthen its manufacturing capabilities with the future hydrogen locomotive conversions, SERA acquired RailPower earlier this year. Significant driver for the acquisition was its proven engineering expertise that directly supports the broader goal of manufacturing both hydrogen gasifiers and zero-emission locomotives in-house.
Fueling the Locomotive
The locomotive is expected to operate for approximately one to one and a half weeks per fill under typical duty cycles at the Port of West Sacramento. SERA’s local operations run two to four days per week, with shifts lasting roughly eight hours. Under this usage, the hydrogen-powered locomotive is projected to displace around 10,000 gallons of diesel fuel annually.
Hydrogen for SERA 193 locomotive is delivered by truck in compressed form, transported in high-pressure tube trailers from Fort Hunter Liggett, with a driving distance of approximately 250 miles to West Sacramento. Each delivery brings up to 200 kilograms of hydrogen to the West Sacramento fueling site. The hydrogen is stored onboard the locomotive at a working pressure of approximately 350 bar (5,000 psi), while the tube trailers arrive with hydrogen pressurized at 450–520 bar (6,500–7,500 psi) to enable efficient transfer. Refueling follows a cascade transfer model, where hydrogen flows from the higher-pressure trailer storage to the lower-pressure locomotive tanks without the need for mechanical compression. This setup ensures reliable, safe and simplified fueling. Deliveries are scheduled as needed, based on locomotive usage.
The Next Generation
Looking ahead, SERA plans to develop and test three more next-generation locomotives with enhanced performance capabilities. A 2023 grant from the California State Transportation Authority, in collaboration with other agencies, has advanced the project with $19.5 million in funding. Each locomotive will be designed to deliver approximately 2,000 horsepower and will be equipped with four 120 kW fuel cells, for a total power output of 480 kW. Hydrogen storage capacity will increase to 400 kilograms per locomotive, and battery capacity will be expanded beyond the 415 kWh installed in the first-generation unit. These upgrades aim to improve operational range, power output, and system efficiency to meet the demands of future rail operations. Looking further ahead, SERA plans to convert up to 20 locomotives to run on hydrogen.
In its June 2025 press release, Ballard Power Systems (NASDAQ: BLDP;) announced a new supply agreement with SERA for the delivery of 1.5 MW of fuel cell engines, expected later in 2025. Under the agreement, Ballard will provide 12 FCmove®-XD engines—four for each of three locomotives. These modules, specifically designed for heavy-duty applications, offer high reliability, durability, efficiency, and power density.
Network Expansion to Five Plants
The Sierra Line—which runs through Tuolumne and Stanislaus counties—serves a key role in biomass logistics. In Tuolumne County, there is a centralized location where biomass and trash from five counties converges, arriving by both highway and rail. This site will likely serve as the consolidation point for the biomass needed to supply the gasification facilities, from which it will be transported by rail. From there SRC plans to build five 100 ton per day distributed gasifier-to-hydrogen plants and fuel up to 20 locomotives and other customers there. The corresponding hydrogen station in-house development is underway but has not been finalized to date.
Through these innovations, the Sierra Railroad Company has demonstrated a comprehensive, closed-loop solution for converting waste into clean energy —paving the way for a more sustainable future in both railroad transportation and energy production.
