A battery electric multiple unit (BEMU), battery electric railcar or accumulator railcar is an electric multiple unit or railcar whose energy can be supplied from rechargeable batteries driving the traction motors.
Prime advantages of these vehicles is that they do not use fossil fuels such as coal or diesel fuel, emit no exhaust gases and do not require the railway to have expensive continuous infrastructure like electric third rail or overhead catenary. On the down side is the weight of the batteries, which raises the vehicle weight, affecting the range before recharging of between . Currently, battery electric units have a higher purchase price and running costs than petrol or diesel railcars. One or more charging stations are required along the routes they operate, unless operation is on a mixture of electrified and unelectrified track, with the batteries being charged from the electrified track.
Battery technology has greatly improved since the beginning of the 21st century, broadening the scope of use of battery trains, moving away from limited niche applications. Vivarail in the United Kingdom claim their trains have a range of on only battery power, with a 10-minute charging time. These sorts of ranges and battery recharging times greatly widen the scope of use of battery or battery-electric trains. Despite higher purchase, on certain railway lines battery trains are economically viable as the very high cost and maintenance of full line electrification is eliminated. Previously, incorporating lightly used unelectrified lines into an electrified network meant extending expensive electrical infrastructure, making many extensions unviable. Modern battery-electric trains have the ability to operate on both types of track. A number of metro networks around the world have extended electrified metro lines using battery-electric technology, with a number of networks considering the option.
From March 2014, passenger battery trains have been in operation in Japan on a number of lines. Austria has overhead wire/battery trains which became operational in 2019. Britain successfully trialled fare paying passenger hybrid overhead wire/lithium battery trains in January and February 2015.
According to a 2019 analysis by VDE e.V., on a line run more frequently than approximately every 24 to 30 minutes, BEMU is more expensive than electrifying the line and running standard EMUs; for lines run less frequently than this threshold, BEMU is cheaper.Alternativen zu Dieseltriebzügen im SPNV
History
Experiments with accumulator railcars, as they were originally called, were conducted from around 1890 in Belgium, France, Germany, and Italy. Full implementation of battery trains were undertaken with various degrees of success. In the U.S., railcars of the Edison-Beach type, with nickel-iron batteries were used from 1911. In New Zealand, a battery-electric Edison railcar with a range of operated from 1926 to 1934 on the long Little River Branch line. The Drumm nickel-zinc battery was used on four 2-car sets between 1932 and 1949 on the Harcourt Street Line in Ireland. British Railways used lead-acid batteries in a British Rail BEMU from 1958 to 1966 on the 38 mile long Aberdeen to Ballater line in Scotland. The BEMU was a success, but decommissioned as the line was closed. A BEMU has been restored operating as a shunting train until proper battery charging facilities are built. In Germany between 1955 and 1995 Deutsche Bahn railways successfully operated 232 DB Class ETA 150 railcars utilising lead-acid batteries.
Supercapacitors
A number of tramway manufacturers are offering battery tramcars that combine the traction battery with a supercapacitor that will be charged at each stop. The main motivation for the usage of battery-powered tramways is to avoid railway electrification system installation. Using boost charging at each stop allows to lower the size of the required traction battery. This technology is hoped to be transferred to full trains.
The CAF Urbos 3 tramways was ordered for the Seville MetroCentro with the Acumulador de Carga Rápida system which uses short overhead wires at each stop for charging. The Seville trams have been operating since Easter 2011.
Siemens three car trams are to be used for Education City in Doha, the capital of Qatar.Qatar Foundation to get turnkey tram system from Siemens Siemens website, 30 July 2012 The network opened in 2010. No overhead wires were installed, as the 10 Avenio trams will be powered by the Siemens Sitras HES system (Hybrid Energy Storage), a combination of a supercapacitor and a traction battery that are charged at each stop through an overhead conductor rail.
A Combino tramway using four car tramsets equipped with the Sitras HES system has been in regular service from Almada to Seixal, Portugal, since November 2008. It is capable of running up to distances of without overhead wires.
A number of catenary-free tramways have opened in China that recharge at tram stops and terminals. The Huai'an tram line in China, opened in February 2016. The line is entirely catenary-free utilising battery-powered trams supplied by CRRC Zhuzhou which recharge at tram stops.
By country
Argentina The Quebrada de Humahuaca Solar Train () is a regional tourist service that operates between the cities of Volcán and Tilcara in Jujuy Province, Argentina. The train service operates within the Quebrada de Humahuaca, a UNESCO World Heritage Site.
The service, formerly operated by state-owned Ferrocarriles Argentinos, is operated by the Government of Jujuy Province, and is the first solar train in the Americas, and the second in the world after the Byron Bay Train. The train line was inaugurated in June 2024.El Tren Solar de la Quebrada será inaugurado en el mes de junio on Somos Jujuy, 22 Apr 2024Comenzó a funcionar el tren turístico de la Quebrada de Humahuaca on En el Subte, 19 Jun 2024
Although the original intention was the multiple units were propelled by photovoltaic solar energy, in May 2022 the government of Jujuy acquired two battery electric units to Chinese manufacturer CRRC Tangshan. The train batteries are charged with solar energy. Each unit has 70 seats and can reach a maximum speed of .Jujuy firmó un acuerdo con CRRC para el tren de la Quebrada de Humahuaca, Enelsubte, 10 May 2022
The local Government also announced that train batteries would be recharged at solar energy plants located in the Quebrada de Humahuaca.Gerardo Morales mostró el tren solar para Jujuy, único en el mundo on Diario Popular, 28 Apr 2023
Australia
The Byron Bay Train service in Byron Bay, New South Wales operates a heritage 600 class railcar. The railcar was formerly diesel powered which was operational from 1949 to 1994. The railcar had the diesel equipment stripped out with electric traction motors fitted, being converted to solar power using a battery set to store solar generated energy from the cars' roof panels. The solar train came into operational use on a formerly disused section of line through Byron Bay in 2017. It is believed to be the world's first solar-powered train.
CAF Urbos 3 supercapacitor powered trams operate on the Newcastle Light Rail network with trams being recharged at each stop. The Canberra and Parramatta light rail networks are also planning to introduce battery powered CAF Urbos 3 vehicles on their networks. They will operate on battery power on select parts of their networks.
Austria The Austrian Federal Railways has purchased 189 Siemens Desiro ML trains from 2013 to 2020. One of these trains was converted to a battery electric multiple unit and branded as cityjet eco. The battery-electric version of the Siemens train is equipped to operate with batteries and overhead wires, with a battery only range of reaching a maximum speed of in battery mode. The trains are to be tested on regional and suburban rail lines on electrified and unelectrified track. The test services began in September 2019 on the Kamp Valley line between Horn and St. Pölten.
Cuba
In 1912, the ordered a battery railcar by Thomas Edison and Ralph H. Beach.
Croatia For the needs of the national railway company Croatian Railways the KONČAR Group and their subdivision of KONČAR – Electric Vehicles is developing units of BEMU and BMU. First units entered use in 2025, with BEMU in May 2025, and BMU in September 2025. BEMU units, capacity of 304 passengers, seating 157, have a possibility to run on overhead line 25kV/50 Hz or on battery power with 631 kWh of storage. BMU units, capacity of 216 passengers, seating 113, run on battery power with 736 kWh of storage. Manufacturer also provides charging stations with 1MW power output.
Denmark From the end of 2020, Stadler FLIRT Akku battery trains would be trialled on two lines, the Helsingør to Hillerød line in Northern Sjælland, and the Lemvig line in Northwestern Julland. The trains were planned for 2024, but the Lemvig Line started operating the first Siemens Mireo battery train in late 2025.
France In January 2021, Bombardier signed a new contract to retrofit and introduce a pre-series of five AGC battery-operated trains by 2023, in collaboration with SNCF and five French regions including Auvergne-Rhône-Alpes, Hauts-de-France, Nouvelle-Aquitaine, Occitanie and Provence-Alpes-Côte d'Azur. The 5 AGC trains will be modified into battery-operated to help decarbonise French rail transport. The idea is to convert dual-mode (catenary and diesel-powered) high capacity self-propelled trains to dual-mode battery-powered AGCs. This project offers a proof of concept and a way forward to eliminating diesel trains by 2035, a target set by the French government and SNCF.
Germany
In 1887, the first German accumulator railcars were placed in service by the Royal Bavarian State Railways.
DB Class ETA Pre-Second World War classes ETA 177 to 180. The post-war DB Class ETA 176 (later 517) and finally ended with DB Class ETA 150 (later 515). The latter were used until 1995 having been since modernised into the Nokia ETA, painted light grey and green and deployed onto the so-called Nokia Railway (timetable number RB 46), nowadays the Glückauf-Bahn from Gelsenkirchen via Wanne-Eickel to Bochum.
Stadler Flirt Akku In July 2019, the Schleswig-Holstein rail authority NAH.SH awarded Stadler a €600m order for 55 battery-powered Flirt Akku multiple unit trains along with maintenance for 30 years. The trains, which offer of battery range, were planned to start entering service in 2022 replacing DMUs on non-electrified routes. Finally, the SH-XMU program inaugurated the trainsets in increments between 2023 and 2025.
Siemens Mireo Plus B The five routes of: Offenburg to Freudenstadt/Hornberg, Offenburg to Bad Griesbach, Offenburg to Achern, Achern to Ottenhöfen and Biberach (Baden) to Oberharmersbach-Riersbach started to operate from April 2024 on electrified and unelectrified track, the 120 seat Siemens Mireo Plus B battery-powered/overhead power line trains. On only battery operation the trains have a range of .
Georgia