Zero/Low-Emission Locomotive Global Roundup (Updated)

Written by Alex Luvishis, Ph.D
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Computer simulation of BNSF HH20B HFC (hydrogen fuel cell) switcher No. 1205.

By 2050, in accordance with the Paris Climate Agreement, zero-emission locomotives may have completely replaced conventional diesel-powered equipment on the railways of the world. Current development of zero-emission switcher locomotives, combined with practical operating experience, increases this likelihood in the foreseeable future. It will be increasingly possible to determine the optimal type or types of zero- or low- emission locomotives to replace conventional diesel units.

Today, four types of zero- or low-emission locomotives are being developed. These are self-contained battery-electric, electric-battery (operating off overhead catenary or internal batteries), hydrogen fuel cell (HFC), and units with upgraded diesel engines using low-carbon renewable diesel or biodiesel, hydrogen/diesel blends, and even an ammonia/hydrogen blend.

While zero-emission switcher locomotives and passenger trainsets have appeared on the world’s railways, until recently, no technology has been developed that would provide enough power for main line locomotives. Now such technologies are available, and prototype locomotives have been built.

Below are brief descriptions of many such locomotives in current or planned operation on several railways of the world.


Progress Rail has developed a family of battery locomotives designated EMD® Joule. Some of them can be applied in switcher operations. The EMD® Joule is available five configurations, new or repowered (“R” nomenclature)—SD70J (6 axles, 8.0 MWh maximum battery capacity); SD70J-BB (8 axles, 14.5 MWh); SD40JR (6 axles, 4.0 MWh); GT38JB (4 axles, 4.0 MWh); GT38JC (6 axles, 4.0 MWh)—these units all feature regenerative braking for battery recharging. Customers can specify what they desire in MWh, up to the maximum rating. The modular EMD® Joule Charging Station provides stationary charging in 700- and 1,400-kW configurations.

EMD® Joule SD40JR testing at MxV Rail, Pueblo, Colo. William C. Vantuono photo.

An EMD® Joule SD40JR is now operating at the Port of Los Angeles with Pacific Harbor Line. The locomotive is six-axle (C-C) and equipped with an asynchronous traction drive. It can operate continuously for up to 24 hours without recharging, depending on the initial charge and load. The emission of harmful substances is zero. The battery is charged in regenerative braking mode and delivers energy in traction mode. A similar locomotive is being tested by Brazilian company Vale. Testing began in the fall of 2021 with a car dumper operation at the port of Tubarao. Main parameters: power, 2,240 kW (3,000 hp); starting tractive effort, 493 kN; weight, 118 tons. The battery energy storage is based on reliable lithium iron phosphate (LiFePO4) batteries. Bogies for 1,000 mm (meter) gauge were used on the Vale locomotive.

In Southern California, BNSF will be taking delivery next year of up to four SD70Js with charging stations for continuous operation. Their 8,000 kWh of storage capacity will make them “the most powerful battery-electric locomotives in North America.” BNSF’s acquisition is funded in part by CARB (California Air Resources Board) and EPA grant funding.

At 14,500 kWh, the SD70J-BB offers the largest known battery capacity in the industry. BHP Western Australia Iron Ore will be testing two beginning early next year. 

Wabtec “Version 1.0” FLXdrive. William C. Vantuono photo.

In October 2018, Wabtec announced a plan develop a main line battery locomotive based on the AC Evolution Series diesel locomotives. In early January 2021, testing began on BNSF of the FLXdrive. Two three-axle bogies and four asynchronous (AC) traction motors are used, which drive the outside axles of each bogie (A1A-A1A). The carbody contains lithium-ion batteries with a total energy of 2,386 kWh, traction inverters similar to those used on diesel-electric locomotives with AC drive, and a microprocessor control system. Energy storage is based on lithium manganese oxide batteries with a high specific energy. The weight is 195 tons, power is 3,280 kW (4,400 hp), starting tractive effort is 640 kN, maximum speed is 75 mph.

The Wabtec family of battery-electric locomotives, in addition to the 2,386 kW prototype FLXdrive, includes switchers. According to Wabtec, a four-axle locomotive with a capacity of 1,800 kW and an energy of 2,700 kWh and a weight of 127 tons is under development. 150 similar locomotives with an energy of 1,500 kWh and an axle load of 23 tons will be manufactured jointly with the railways of
Kazakhstan beginning in 2024.

The FLXdrive program is progressing to the next level. The 2,400 kWh “Version 1.0” test with BNSF registered an 11% fuel savings operating in a consist with two diesel-electrics, vs. a three-unit diesel-electric. Two of the latest version, the 7,000 kWh FLXdrive 2.0, are shipping at the end of this year
to Australia for a trial with BHP Western Australia Iron Ore (in the same trial as Progress Rail’s SD70J-BB).

This will be followed by the FLXdrive 2.5, which replaces the NMC (nickel-manganese-cobalt) batteries with GM’s Ultium NCMA (nickel-cobalt-manganese-aluminum) technology manufactured by Ultium Cells LLC, a joint venture of GM and LG Energy Solution.

Union Pacific has selected Progress Rail and Wabtec to supply 10 battery-electric switcher locomotives each. The railroad expects the delivery of the first units at the end of 2023; the order should be fully completed by the end of 2024. Testing will occur in California and Nebraska. Calculations carried out by the railroad indicate that, combined, these locomotives will emit 8,000 tons less carbon per year into the environment than the diesel locomotives used today—equivalent to removing 1,600 cars with internal combustion engines from the highway.

CRRC battery locomotive for Thailand.

Energy Absolute in August 2022 took delivery of what it describes as Thailand’s first electric locomotive, a battery-powered unit supplied by CRRC (China Railway Rolling Stock Corp.) Dalian. The locomotive is undergoing testing at Bangkok’s new central station, Bang Sue Grand, which will be the Thai capital’s high-speed terminus as well as the principal station for the conventional 1,000mm-gauge network.The locomotive has a range of 200 km and would offer a 40% saving in energy costs when compared with diesel traction. Energy Absolute has developed a rapid charging system that can charge the locomotive’s batteries within 60 minutes, as well as a station for changing batteries in under 10 minutes. The battery system was developed in conjunction with Asia Engineering & Service (Thailand), a company that specializes in the repair of traction motors and other electrical equipment.


CRRC is believed to have the world’s longest experience in manufacturing electric-battery switcher locomotives.

In April 2022, an electric-battery switcher locomotive manufactured by CRRC Zhuzhou Locomotive Co. Ltd. (CRRC ZELC EUROPE, parent company of Vossloh Locomotive) arrived in Brazil to operate in the Ponta da Madeira Terminal’s switchyard in São Luis. The six-axle locomotive is equipped with lithium iron phosphate (LiFePO4) batteries with an energy of 1,000 kWh. This unit can operate on a single battery charge for 10 hours.

CRRC ZELC electric-battery switcher.

Hungarian Railways operates a four-axle electric-battery locomotive, No. 461, manufactured by CRRC Zhuzhou that can operate with a power of 850 kW under catenary networks of 25kV, 50Hz AC and 1.5kV DC and from a lithium iron phosphate battery with an energy of 350 kWh. The weight of the locomotive is 72.2 tons, the maximum speed is 100km/h (62 mph), the charge time is 2.5 hours.

Hungarian Railways No. 461 from CRRC Zhuzhou.

Since 2018, CRRC has been developing an electric-battery locomotive for the port of Rotterdam. A four-axle electric locomotive can operate with a power of 2,500 kW under catenary of 25kV, 50Hz or 15kV, 16.7Hz AC; 1,500 kW under catenary of 1.5kV DC; and from a battery with an energy of 300 kWh. The weight of the locomotive is 90 tons, the maximum speed is 100km/h. Delivery of two units should be
completed in 2024.


CRRC’s four-axle, 90-ton DM20-EBB is to be delivered to German railways. Power under catenary of 15kV, 16.7Hz AC is 2,500kW; 500kW when powered by a battery with an energy of 350 kWh.

In October 2020, the Indian Electric Locomotive Depot in Arakkonam, Tamil Nadu converted a WAG5HA series 25kV, 50Hz AC rectifier electric locomotive into an electric-battery locomotive, installing two battery modules. Lead VRLA batteries with a voltage of 110 VDC and a capacity of 1,100Ah were used. Therefore, the energy of the battery is 242 kWh. There are three speed modes when powered by a rechargeable battery.

Having marked the first successful experience with simple electric-battery locomotives, the railways of India decided to create new modern electric-battery units. India’s Chittaranjan Locomotive Works plans to build 10 electric-battery locomotives with lithium-ion traction batteries. The 86-ton locomotive is designed to operate in electrified territory under 25kV, 50Hz AC catenary; in non-electrified areas from a battery. Power under catenary is 980 kW (1,318 hp), 530 kW (718 hp) when operating from a battery. The storage battery has a capacity of 3,000Ah, voltage is 750V. That is, its energy is 2,250 kWh. It is assumed that a fully charged battery can be used for switcher work for up to five hours.

Battery drive operation is currently being researched. For this, a motor car of an electric train was used with an asynchronous traction drive. There is enough space in the car to accommodate the traction battery. Proven converters and traction motors can be used.

Hydrogen and Other Fuels

What is believed to be the world’s first hydrogen fuel cell (HFC) switcher was developed in 2009. The locomotive, HH20B No. 1205, was upgraded from the GG20B “Green Goat” developed by RJ Corman Railpower. The HH20B, in operation on BNSF, uses a fuel cell stack instead of a 200 kW diesel generator set. The fuel cells used are two PEM (proton exchange membrane) modules with a capacity of 150 kW each from the Canadian company Ballard. DC traction motors are controlled by pulse converters. Hydrogen, necessary for fuel cells operation, is stored as a gas in 14 cylinders holding 70 kg under a pressure of 350 atmospheres. The locomotive has passed lengthy operational tests in various climatic conditions. It turned out that the amount of hydrogen on board the locomotive was enough for an average of 11.3 hours of work. The filling time for hydrogen cylinders is 25-45 minutes.

Liquid rather than gaseous hydrogen may be preferable as a fuel for high power vehicles such as main line locomotives. In April 2022, the Korea Railroad Research Institute (KRRI) announced that it is developing a main line liquid hydrogen-electric hybrid locomotive. Power will be 2,700kW; maximum speed 90 mph; range of 600 miles. Its hydrogen refueling speed is expected to be 20% faster than gas hydrogen units. Hydrogen liquefies at or below –253 degrees Celsius. Its pressure is much lower than that of hydrogen gas, so it can therefore be safely stored and transported. The use of liquid hydrogen also reduces fuel weight, which is very important in South Korean railroads, whose main line locomotive axle loads are typically 22 tons. Liquefied hydrogen is seven times more efficient than of gaseous hydrogen. KRRI is developing technologies to produce and transport liquid hydrogen modules. Its plan is to store it in 6 insulated cryogenic modules of 70 kg each (420 kg total). The Institute plans to complete the research part of the project in December 2024 and start commercialization in 2025. As these technologies and components are developed, KRRI plans to test them on trams.

The German Federal Ministry of Education and Research has allocated funds and selected for implementation a pilot project to develop a main line locomotive on Namibian National Railways powered by a diesel/hydrogen fuel blend. Two diesel-electric locomotives manufactured by GE in the U.S. currently operated by Namibian Railways will be converted to use hydrogen, and used in tandem with a newly developed hydrogen fuel tender—a configuration similar to Florida East Coast Railway’s LNG (liquefied natural gas) locomotives. The project, called HyRail Namibia, is expected to be completed in 18 months. The consortium of companies to manufacture the prototype will be led by the African company Hyphen Technical and include CMB. TECH, Namibian National Railways, TransNamib, the University of Namibia and Traxtion. High expectations have been placed on the contribution of CMB.TECH, which has been developing dual-fuel diesel power technologies for two decades. Traxtion supports start-up companies and invests seed capital.

In June 2021, Chinese Railways announced the production of a six-axle switcher locomotive with fuel cells, with 100% local content. The hybrid locomotive has a power of 1,400 kW. To reduce energy loss, the drive uses a DC/DC converter based on Si-C valves and synchronous traction motors with excitation from permanent magnets. The maximum speed of the locomotive is 100 km/h. Starting tractive effort is 520kN. The locomotive is equipped with 12 cylinders and a capacitive tank for storing hydrogen under pressure of 35 MPa. Fully filled with hydrogen, the locomotive can move on level track with a reserve of 24 hours, hauling freight trains weighing 8,000 tons. Compared to electric and diesel locomotives, the locomotive is not only more economical and environmentally friendly, but also quieter, cheaper and requires less maintenance. The hybrid solution helps the locomotive accelerate the train faster than a diesel locomotive of the same capacity.

The next HFC switcher locomotive produced was the SM42 6Dn (Pesa H2loco) locomotive of PESA (Poland). Its wheel rim power is 720 kW and will be used at the Orlen refinery in Płock. It is based on a diesel switcher locomotive. An older four-axle (B-B) locomotive with a speed of 90 km/h, it originally had DC/DC electric transmission and a power of 600kW. The rebuilt, upgraded locomotive will retain its main traction performance. Therefore, it will still be able to haul trains weighing up to 3,200 tons. It is equipped with four 180kW asynchronous traction motors manufactured by TSA (Austria) and two ABB liquid-cooled traction converters (one per bogie). The prototype is equipped with 167.6k Wh LTO traction batteries and two fuel cells of 85kW each supplied by hydrogen tanks with a total volume of 175 kg.

An HFC locomotive for the Sierra Road (California) is a modification of the RP20BD switcher diesel locomotive. The Railpower Co. locomotive is a four-axle unit with three diesel generators with a capacity of 375 kW each. The new locomotive will be equipped with a 200kW Ballard FCmove®-HD fuel cell PEM module and a 500kWh battery. The stock of hydrogen on board the locomotive will be 222 kg. This locomotive should go into operation in 2023.

Since 2017, OptiFuel Systems (U.S.) has been introducing diesel engines using natural gas as fuel on the Indiana Harbor Belt Railway. In testing, only Renewable Natural Gas (RNG) has been found to provide zero emissions.

In June 2022, OptiFuel Systems entered into an agreement with Argentine Railways to convert 400 switcher and main line locomotives to its zero-emission system. The company intends to use its new 500kW engines using RNG and subsequently hydrogen as fuel. For a switcher locomotive with a capacity of 1,500kW, three diesel generator units will be used, that is, a multi-engine locomotive. Assemblies with gas cylinders are placed on and under the carbody frame. For a 1,500 kW locomotive, 18 RNG cylinders (1,480 DGE) or 337 kg of hydrogen are used. The locomotive is hybrid: Along with diesel generators, lithium batteries with an energy of 600 kWh are placed on board.

The first hybrid locomotive project was developed by Alstom in 2013. The main parameters of the three-axle locomotive are track gauge of 1,435mm (standard gauge); weight of 67 tons, maximum speed of 100km/h, and starting traction force of 240kN. Locomotive power is 700kW, diesel generator power and battery power is 350kW. Alstom is currently working to reduce the emission of harmful substances from the locomotive to zero.

In February 2019, Alstom leased its H3 1002 032 locomotive to the German company VPS (Verkehrsbetriebe Peine Salzgitter) for modernization. Today, the locomotive is equipped with a Deutz TCD 12 engine, which has been upgraded to run on hydrogen fuel. After modernization, the locomotive was returned to Alstom for extensive testing. Operation is expected to begin in 2024.

CPKC HFC linehaul locomotive.

In a program originated by Canadian Pacific, CPKC’s (Canadian Pacific Kansas City) H20EL (Hydrogen Zero Emission Locomotive) prototype, now testing, is equipped with PEM fuel cells. CPKC upgraded an existing SD40-2F diesel-electric locomotive with a capacity of 3,000 hp (2,237 kW) and weighing 368,000 pounds (184 tons), with 511.5 kN STE (starting tractive effort). The diesel generator set has been removed from the locomotive and replaced with 200 kW Ballard HFC (hydrogen fuel cell) modules and battery energy storage. The HFC modules use cylinders of pressurized hydrogen gas. Bilton Welding and Manufacturing Ltd. is wrapping up work on the second of three units. The first, currently under test in line-haul service, marked a milestone in November 2022 with its first revenue move. Bilton, based in central Alberta, has provided fabrication expertise and services to CPKC since the railroad’s HFC program began in December 2020. In November 2021, CP received a $15 million 50% matching grant from Emissions Reduction Alberta (ERA) to expand the initiative to three locomotives (two line-haul units and one switcher), install hydrogen production facilities at two locations, and create a “global center of excellence in hydrogen and freight rail systems” in Alberta. 

BNSF, Caterpillar, Inc. and Chevron U.S.A., Inc. have teamed on a locomotive pilot to “confirm the
feasibility and performance of hydrogen fuel for use as a viable alternative to traditional fuels for line-haul rail.” The companies, which made the announcement on Dec. 14, 2021, signed a memorandum of
understanding (MOU) for the project. Progress Rail  will design and build a prototype hydrogen fuel cell-powered locomotive for line-haul and/or other rail service; Chevron will develop the fueling concept
and infrastructure; and BNSF will make available its lines for prototype testing.

Alstom, whose success with its Coradia iLINT HFC passenger trainset is well known, is collaborating with ENGIE on a dual-power locomotive that combines a traditional electric locomotive with an HFC generator car. The technology uses Cummins PEM fuel cells. In electrified territory, traction motors are fed through converters drawing power from catenary. On non-electrified sections, traction motors are fed through converters drawing power fuel cells installed in the generator car. The electric locomotive and the car are connected by power cables. In 2025, freight trains operated by Nestlé Waters France carrying VITTEL mineral water between the Vosges plant (Epinal station) and distribution centers in Vittel/Arles (a 375-mile distance) and Vittel/Montreuil-Belley (472 miles) are expected to be hauled by these locomotives.

Ammonia/hydrogen-electric for FMG (Fortescue Metals Group) Railway, Australia.

Gaseous ammonium can be decomposed using a catalyst into a mixture of ”green” nitrogen and “green” hydrogen in a process called “cracking.” Before entering the cracking unit, liquid ammonium enters an evaporator, where it is converted to a gas. Ammonigy of Stuttgart, Germany, is developing such a system for Deutsche Bahn (DB, (German Rail) locomotives, working with Fortescue Future Industries Pty. Ltd. (FFI). Ammonigy’s Fuel Refinement System breaks down a small amount of ammonium into hydrogen and nitrogen. The hydrogen is then mixed with the remaining ammonium as a flammable gas (hydrogen acts as an “igniter” for the ammonia fuel), allowing CO2-free combustion. An exhaust treatment system minimizes NOx emissions. To evaluate the reliability of the upgraded engine and continuously monitor the emissions levels, DB worked with FFI to convert two Dash 8-40CM diesel-electrics originally built by GE into prototypes for testing with FMG (Fortescue Metals Group) Railway, an iron ore hauler in Perth, Australia, in the Pilbara Region. CD4301 and CD4304 are standard-gauge units. As diesel-electrics, these 391,600-pound (196-ton) locomotives were rated at 4, 000 hp (3,000 kW) and continuous tractive effort of 108,800 pounds (483 kN) at a speed of 11 mph (18 kph).

Wabtec’s venture into hydrogen includes HFC as well as burning hydrogen inside an internal combustion engine. The company is working with GM to utilize its Hydrotec fuel cell technology in a hybrid unit, with batteries supplying traction power. The fuel cells would be trickle charging the batteries. Wabtec will be working toward 65% efficiency, compared to 40%-42% with an internal combustion engine.

Cummins’ alternative fuel initiatives took flight after it purchased, for $290 million, Canada-based Hydrogenics in 2019. The company intends to become a major player in HFC, battery-hybrid and “fuel-agnostic” (hydrogen, natural gas, diesel and biofuels including HVO) heavy-equipment engine technology.

Alex Luvishis, Ph.D. for 18 years headed the laboratory that developed control systems for Russia’s first electric locomotives and asynchronous traction motors in the former USSR. For a further seven years, he headed the rolling stock department at the Institute of Technical Information of Railway Transport in Moscow. Dr. Luvishis is the author of more than 100 articles on electric traction drives and the book “Hybrid Rail Vehicles,” published in 2009. His interests are asynchronous traction drive systems for modern rolling stock, and hybrid drive systems for trams, suburban and regional trains and switching and main line locomotives. He has lived in the U.S. since 1999. 

Editor-in-Chief William C. Vantuono contributed to this story.