Abstract
The world is transitioning to a new era of transport, where achieving sustainability is paramount. Among other modes of transport, rail-based transit systems offer a more viable and efficient alternative to move both passengers and goods. Apart from facilitating connectivity, Railways have also been acting as the core support for the economies of many nations, like India. The prime force behind this transition is the evolution of locomotives, which continuously pushed the railways to go beyond their capacities and serve the increasing business and commuter demands. The journey, which started with steam-powered locomotives, gained extra wheels with the introduction of diesel-powered locomotives later, and electric-powered engines helped the railways to achieve their speed goals without impacting the environment. The electric locomotives, however, require a dedicated infrastructure along the tracks, which escalates the cost of the project and also increases the completion time.
The challenges associated with the current rail system can be effectively addressed through the implementation of battery-powered trains. A Battery Electric Multiple Unit (BEMU), or accumulator railcar, is defined as an electrically propelled multiple unit or railcar that derives its energy from rechargeable batteries, which in turn power the traction motors.
The road to achieving sustainability is long, and it will require strategic planning, necessary policy frameworks, coupled with the integration of modern technologies that can together create a future for rail transit systems which is safe, affordable, fast, reliable and most importantly, sustainable. This study examines the potential of battery-powered trains, which can be seen as an alternative in advancing green mobility.
Conceptualisation of Battery-Powered Locomotives: A Future Rooted in the Past
One of the most advanced technological developments making a return is the shift toward electric-powered transport systems. As awareness of the environmental impact of fossil fuel-based vehicles grew, efforts to find cleaner alternatives led to a renewed interest in the electric mobility idea that has existed since the early days of rail and automotive history.
Robert Davidson, a trained chemist with a profound interest in electromagnetism, successfully developed the first battery-powered locomotive in 1837. He subsequently featured this innovative vehicle at the “Electromagnetic Exhibition” held in 1839. The locomotive had the capacity to transport 2 individuals. Davidson later enhanced his creation by developing a full-sized prototype electric locomotive. This locomotive was powered by galvanic cells and was designated “Galvani” in honour of the esteemed Italian scientist Luigi Galvani.
In 1842, this locomotive operated at a speed of four miles per hour on the Glasgow to Edinburgh line. Its dimensions were 16 feet in length, and it weighed approximately 6 tons. Unfortunately, there existed opposition to the advancement of electric locomotives, as some individuals were apprehensive about the potential replacement of steam engines, which led to the destruction of Galvani by a group of detractors.
First Rechargeable Battery: Foreground for the Battery-Powered Trains
Gaston Planté, a French physicist, developed the lead-acid battery, which set the stage for the practical electric locomotives, as this was the world’s first rechargeable battery.
Throughout the 19th and 20th centuries, developments in battery technology progressed gradually. Researchers made improvements in power output, energy efficiency, and operational lifespan. While the pace of innovation was incremental, each development contributed to making battery-powered systems more viable for practical applications.
In this context, Robert Davidson’s work played a foundational role. By demonstrating the potential of electricity as a motive force, Davidson laid the groundwork for the evolution of modern electric and battery-operated locomotives that today form an integral part of the sustainable and efficient rail transportation system.
20th Century Developments
Operations of(BEMUs): Battery electric multiple units (BEMUs) have been in service since the early 20th century in various countries (e.g., Edison-Beach railcars, 1920s New Zealand, 1950s UK and Germany).
1910: A crosstown railcar in New York City began service using Edison storage batteries as its power source in March 1910. The vehicle was engineered by Ralph H. Beach, representing the Federal Storage Battery Car Company. This train used nickel-iron batteries.
1928: The Railway Storage Battery Car Company built Central Vermont in 1928. It was designed for double-end operation. This self-propelled railcar featured onboard storage batteries, allowing it to operate independently of overhead wires. It was part of a broader effort during the early 20th century to develop alternative propulsion methods for rail transport.
1913-1929: Battery-Powered Trams in New Zealand
New Zealand’s first battery-powered public transport vehicles were used in Gisborne between 1913 and 1929. However, due to financial constraints, the trams turned out to be unsuccessful.
Between 1926 and 1934, New Zealand operated its second battery-electric public railcar service, which ran between Christchurch and Little River. This initiative was financially sustainable. However, a depot fire brought this early experiment in battery-powered rail transport to an abrupt end.
1955-1995 Era of Battery-Powered Trains in Germany
From 1955 to 1995, Germany’s Deutsche Bahn pioneered the large-scale use of battery-powered trains. These trains were equipped with lead-acid batteries that were capable of generating over 300 kW of power. These trains could reach a top speed of 100 km/h; they combined efficiency with environmental consciousness at a time when diesel traction dominated non-electrified corridors. Their distinctive technology and reliable performance led to a variety of nicknames, including “Battery Lightning,” “Battery Acid Bombers,” “Socket InterCitys,” and “Pocket Torch Express. Their success laid the groundwork for modern battery-electric multiple units (BEMUs.
British Railways’ Experiment With Battery-Powered Trains
From 1958 to 1966, British Railways operated a Battery Electric Multiple Unit (BEMU) which ran on lead-acid batteries on the 38-mile Aberdeen to Ballater line in Scotland. This initiative represented one of the earliest efforts in the UK to explore battery-electric traction for passenger rail services.
British Railways conducted an early experiment with battery-electric traction by converting a two-car set for use on the Deeside line. This battery-electric train began service in 1958 on the scenic route between Aberdeen and Ballater. It offered a quiet, low-emission alternative to diesel units. Although it operated in passenger service for only 4 years, the train played an important role in testing new propulsion technologies.
All these examples outline a fact that the potential of battery-powered trains was realised in past as well; however, they could not gain much attention due to the lack of research and prominence of diesel-powered locomotives. Although today, when safeguarding the environment is imperative, this technology is experiencing a resurgence as a viable alternative that can contribute to the achievement of sustainable mobility objectives.
Essential Components in Battery-Powered Train
Battery-powered trains don’t rely on a dedicated infrastructure alongside the tracks for the traction power. BEMU utilises onboard batteries for powering the traction motors of the train. Their performance depends on a set of integrated systems that manage energy storage, propulsion, control, and safety. The essential components include:
- OESS (Onboard Energy Storage System): This is the most essential component of BEMUs. Primarily, it is responsible for storing and managing the electric energy. This system relies on the batteries that are installed in the train itself. It has the capacity to store energy obtained from the Overhead Electrification (OHE) system as well as from the regenerative braking process. This functionality allows the train to utilise stored energy in areas where OHE infrastructure is not available. When operating under catenary power, the Onboard Energy Storage System (OESS) simultaneously charges and discharges the batteries. Furthermore, this system provides power to the train’s auxiliary systems, including lighting, air conditioning, and communication systems.
Type
- Lithium-ion batteries: These are predominantly used for high energy density and fast charging.
- Lead-acid batteries: The conventional BEMU used these batteries due to their cost-effectiveness.
- Hydrogen Fuel Cells:
Example
- Hitachi’s DENCHA BEMU (Japan) operates on a lithium-ion battery.
- Wabtec’s FLXdrive (USA), which is the world’s first 100% battery-electric, heavy-haul locomotive, has a 2.4 MWh battery system.
- Power Conversion System (Inverters & Converters): This system converts the DC power received from the batteries into AC for the traction motors. It also manages the Regenerative Braking System by converting the AC (generated during braking) back into DC for storage.
Example
- Siemens’ Desiro ML Cityjet Eco (Austria), can manage dual-mode operation; it is designed to draw power from batteries on non-electrified tracks and switch to overhead power where available.
- Train Control and Management System (TCMS): This is an integral part of every train. It monitors and manages all the onboard systems, including traction, braking, battery usage, auxiliary systems, and diagnostics.
- Charging System: All the BEMUs are equipped with a charging system which facilitates the replenishment of battery energy via various methods, depending on infrastructure and route. Some of the methods include: Plug-in Charging, Pantograph Charging, Inductive Charging (currently under experiment), etc.
- Battery Management System: BMS’s primary role involves monitoring voltage, current, temperature, and state of charge (SoC) of battery cells. It protects overcharging, deep discharge, and thermal runaway.
New Generation Battery-Powered Trains: Tracing the Future of Sustainable Rail Transport Systems
Hitachi Rail set a precedent in the rail transportation industry by introducing the world’s first AC electrified, overhead power storage electric train, known as “DENCHA” (Dual Energy Charge train). This train commenced operations on October 19 in Japan, specifically on the 11-kilometre Orio-Wakamatsu section of the Chikuho Line.
DENCHA is a BEC Series 819 train and is operated by JR Kyushu. The train has a top speed of 120 kmph. Within just 5 years of operations, DENCHA reduced CO2 emissions by 2,700,000 kg.
Working of DENCHA
In Electrified Section: When running on an AC electrified section, DENCHA operates like a conventional train. It uses a pantograph to draw electricity from the overhead line. During transit and when halting, the AC power from OHE is converted to recharge the onboard battery
In Non-Electrified Section: In areas without overhead lines, the pantograph is lowered, and the train runs entirely on battery power. While braking in either mode, DENCHA utilises regenerative braking for recharging the batteries.
Environmental & Operational Benefits: DENCHA operates without an internal combustion engine, in contrast to conventional diesel railcars. This prevents engine noise, vibration, and exhaust emissions. In addition, this contributes to a reduction in maintenance costs through the efficient utilisation of energy. In 2017, DENCHA won the 60th Blue Ribbon Award.
Note: The EV-E301 series and the EV-E801 series represent additional models of battery-powered trains currently in operation in Japan.
- Europe’s First Tri-Brid Train: Blues
National governments across Europe are striving to achieve the Net Zero target by the year 2050. In alignment with this objective, Trenitalia, an Italian train operator, has partnered with Hitachi Rail to develop Europe’s inaugural tri-brid train, which has been designated as “Blues.”
The Blues started operations in Sicily, Italy, in December 2022. The train is capable of reaching a top speed of 160 kmph. The Blues an anticipated service life of up to 25 years, assuming daily operation of 16 hours.
Blues’ Hybrid Technology
The Blues train incorporates hybrid technology to power its traction motors. This innovative train utilises a combination of three energy sources: electricity, diesel, and battery. which empowers it to run on both electrified and non-electrified routes. In terms of sustainability, Blues reduces carbon emissions & fuel consumption by 50%.
Modern Signalling System: The Blues is equipped with the European Rail Traffic Management System (ERTMS) signalling framework.
- Mireo Plus B: Siemens Mobility’s Hybrid Train Begins Operations in Germany
Siemens Mobility’s battery-electric trainset, the Mireo Plus B, officially entered passenger service in Baden-Württemberg, Germany, on 8 April 2024.
These hybrid trains are designed to operate on both electrified and non-electrified routes. While running under electrified overhead lines, they use a pantograph to draw power and simultaneously charge their onboard lithium-ion batteries. When operating in areas without electrification, the train switches to battery mode, enabling it to cover distances of up to 80 kilometres, with tested capability extending to 120 kilometres under optimal conditions.
A step toward Sustainability
The Mireo Plus B is part of Siemens’ broader effort to reduce dependence on diesel-powered rail vehicles. The trains are expected to help lower diesel consumption by approximately 1.8 million litres per year across the network.
Mireo Plus B is equipped with an advanced traction system which empowers the train to reach speeds of up to 160 km/h in both battery and catenary modes.
These examples from across the world show the paradigm shift within the rail transit industry toward more efficient and sustainable alternatives. Nevertheless, each project or initiative presents its own set of challenges and benefits. Similarly, the adoption of battery-powered trains offers a promising pathway toward a sustainable future for rail transit; however, several roadblocks remain that must be addressed to facilitate this transition.
Benefits of Battery-Powered Trains
1. Environmental Impact:
Battery-powered trains do not emit CO₂ during operation. Unlike diesel-powered trains, which emit carbon dioxide (CO₂), nitrogen oxides (NOₓ), and particulate matter, battery trains help reduce air pollution. This aligns with global decarbonisation targets. For instance, Hitachi’s DENCHA battery train in Japan has reportedly cut down CO₂ emissions by over 2.7 million kilograms in its first five years of service.
2. Noise Reduction
Battery-electric trains operate more quietly than diesel locomotives because they lack internal combustion engines. This makes them particularly suitable for routes that pass through densely populated urban or residential areas.
3. Lower Maintenance Costs
BEMUs have fewer moving mechanical components than diesel-powered trains. The absence of components such as diesel engines, fuel injectors, and exhaust systems means reduced wear and tear, translating to lower maintenance costs over the train’s lifecycle.
4. Operational Flexibility
Battery-powered trains can run on both electrified and non-electrified tracks, enhancing network flexibility. This is especially beneficial in regions where partial electrification exists or where full electrification is economically or geographically challenging.
5. No Additional Infrastructure Required:
One of the most practical and cost-effective advantages of battery-powered trains is their ability to operate without the need for continuous external power infrastructure such as overhead electric lines (catenary systems) or third-rail systems. This means that rail operators can deploy battery-powered trains on non-electrified routes without investing in expensive and time-consuming electrification projects. As a result, battery trains offer a flexible solution for expanding rail services to remote or rural areas, where laying down new infrastructure might be economically unviable or environmentally disruptive. Moreover, this reduces maintenance requirements and the long-term operational costs typically associated with fixed power supply systems.
Challenges in Deploying Battery-Powered Trains
1. Limited Range and Battery Capacity:
One of the primary limitations of battery-powered trains is their short range compared to diesel or fully electrified trains. Battery capacity restricts the distance a train can travel on a single charge, which makes them suitable for short routes unless charging infrastructure is strategically placed along the line.
2. Long Charging Times:
Recharging large battery packs can take considerable time, which can potentially affect train scheduling and turnaround times. While fast-charging technologies are being developed, current charging cycles may not yet meet the demands of high-frequency operations.
3. High Initial Costs:
The cost of battery technology, along with required onboard systems for energy management and safety, can be higher than conventional diesel or electric train systems. Additionally, retrofitting existing rolling stock with batteries involves substantial capital investment.
4. Battery Degradation Over Time:
A critical challenge with battery-powered trains is that the performance of train batteries declines over time due to charge-discharge cycles, temperature exposure, and ageing. This degradation can lead to reduced operational range and efficiency, and will require periodic replacement of battery modules, which will escalate the maintenance costs.
5. Weight and Space Constraints:
Battery systems add considerable weight and require dedicated space within the train design. This can affect the train’s energy efficiency, limit passenger capacity.
6. Environmental and Safety Concerns:
Battery production involves the extraction of rare earth elements and chemicals that have environmental implications. This questions the sustainability which is offered by battery-powered trains.
7. Charging Infrastructure Requirements:
Although battery-powered trains eliminate the need for full route electrification, they still require dedicated charging stations or facilities at terminals and depots.
8. Limited Proven Deployment at Scale:
Battery-powered trains are still in the early stages of commercial deployment worldwide. To enable widespread adoption by countries like India, there is a need to scale and engineer these systems for high-speed and heavy-haul operations, while upholding performance and safety standards under diverse and harsh weather conditions.
Conclusion
Battery-powered trains offer a practical approach to achieving cleaner and more efficient rail transport. While not entirely new, their relevance has increased in recent years due to growing environmental concerns and advancements in battery technology. The deployment of BEMUs across countries like Japan, Germany, and Italy highlights a global shift towards low-emission mobility solutions that reduce dependence on fossil fuels. These trains offer advantages such as reduced emissions, lower noise, and the ability to operate on non-electrified tracks, making them suitable for regional and semi-urban routes. However, technical limitations, including battery weight, restricted range, and infrastructure requirements, still pose challenges. Continued research, supportive policies, and investment in charging infrastructure will be critical to enabling wider adoption. As part of a diversified strategy alongside electrification and hydrogen-based systems, battery-powered trains can contribute meaningfully to building a more sustainable and flexible rail network for the future.
