Are Battery-Powered Trains the Future? A Look at Diesel’s Potential Replacement

• Battery-powered trains provide a cleaner, quieter alternative to diesel, promoting sustainability in rail transportation by reducing pollution and noise.
• Innovations like Hitachi’s tri-mode trains are cutting emissions and operational costs, particularly on non-electrified rail lines, with hybrid models offering more flexibility.
• Despite challenges related to range and infrastructure, battery-powered trains are advancing toward helping the UK achieve its net-zero emissions goal by 2050.

Railway networks, a cornerstone of transit for decades, are now undergoing a significant transformation. Diesel-powered trains, which have long operated on non-electrified lines, are set to be replaced by battery-powered alternatives. This transition marks a significant step toward cleaner, more sustainable rail transportation.

Why Are Battery-Powered Trains Gaining Momentum?

The shift toward battery-powered trains is driven largely by environmental concerns. Diesel trains emit harmful pollutants that contribute to air pollution and climate change, while battery-powered alternatives produce zero emissions, making them a much greener option. Beyond environmental benefits, battery-powered trains offer operational advantages as well. They run more quietly than their diesel counterparts, reducing noise pollution in nearby communities. With fewer moving parts, these trains also incur lower maintenance costs, and by eliminating diesel emissions, they help improve air quality and public health.

Safety Considerations for Battery-Powered Trains

Safety is a top priority when introducing any new technology, and battery-powered trains are no exception. Powered by advanced lithium-ion batteries, commonly used in electronics, these trains are equipped with multiple safety features to prevent overheating, fires, and explosions. They also include cutting-edge fire detection and suppression systems to handle potential incidents. In addition, comprehensive emergency protocols are in place to manage battery failures or accidents, while routine inspections and maintenance ensure the trains’ ongoing safety and operational reliability.

Challenges and Limitations of Battery-Powered Trains

While battery-powered trains offer numerous advantages, they also present certain challenges. A key limitation is the current range of battery technology, which confines these trains to shorter routes or those with frequent charging stations. Upgrading existing rail infrastructure to accommodate battery-powered trains, such as installing charging points, requires substantial investment. Moreover, ensuring the efficient recycling and disposal of batteries is vital for minimising environmental impact and ensuring long-term sustainability in the rail industry.

The Future of Rail Transportation: A Path to Sustainability

Despite the challenges faced today, the future of rail transportation is steadily leaning toward more sustainable, electrified options. With ongoing advancements in battery technology, battery-powered trains are expected to achieve greater range and improved efficiency, making them increasingly viable for longer routes. Additionally, hydrogen-powered trains present a promising alternative for decarbonising the rail sector, offering a complementary solution to battery technology. These innovations are primed to drive a major transformation in rail transportation, paving the way for a greener, more sustainable future.

Battery-Powered Trains in the UK: Steps Towards Electrification

As the UK’s diesel train fleet nears the end of its service life, the railway industry is increasingly looking to battery-powered alternatives. Currently, trains in the UK are powered by overhead electrified wires or onboard diesel generators, with many models capable of switching between the two. The adoption of battery-powered trains would eliminate the need for overhead wires on the many unelectrified routes still in use across the country.

Hitachi’s Newton Aycliffe factory has already completed testing on an innovative “tri-mode” train that replaces a diesel generator with lithium batteries. This change could reduce fuel consumption by up to 50% on non-electrified tracks. Building on this success, Hitachi is planning a fully battery-powered vehicle capable of travelling up to 90 kilometres (56 miles) on unelectrified lines.

Meanwhile, Siemens is advancing its battery-powered train projects at its Goole facility. Orders for these trains are expected from operators such as ScotRail, Great Western Railway, and Transport for Wales. While battery-powered trains are already operational in countries like Japan and Germany, adapting them to the UK’s specific rail infrastructure will require overcoming unique challenges.

Battery Technology and Operational Efficiency

Diesel-electric trains typically draw power from overhead lines on electrified tracks, switching to diesel generators on unelectrified sections. Hitachi’s tri-mode train takes this a step forward by replacing one of the diesel generators with 16 lithium-ion batteries, similar to those used in electric vehicles. These trains automatically switch between power sources, with the batteries primarily deployed in urban areas and stations, where reducing emissions and noise pollution is crucial.

The batteries can be recharged while the train is running on electrified tracks or during brief stops, typically taking just 10-15 minutes. Additionally, existing diesel-electric trains can be retrofitted with these batteries, providing a cost-effective alternative to fully battery-powered models.

A Change in the Political and Technological Landscape

The first lithium-ion battery-powered train debuted in Japan in 2016, nearly 60 years after Scotland introduced the first battery-powered trains using lead-acid batteries. Koji Agatsuma, Hitachi’s technical leader, attributes the UK’s growing interest in battery-powered trains to recent advancements in battery technology and a political shift towards sustainability. As batteries become smaller, more powerful, and more efficient, they align with the government’s goals of promoting environmentally friendly, cost-effective, and reliable transportation solutions.

However, challenges remain. Hitachi’s tri-mode design was developed in response to the limited range of current battery technology, which prevents trains from covering all of the UK’s unelectrified rail sections. While additional rail sections could be electrified, the cost is significant, with Network Rail estimating that electrification costs range from £1 million to £2.5 million per kilometre. To address these issues, Siemens has proposed the addition of short electrified sections along routes, coupled with rapid charging stations. While Hitachi’s test trains can travel up to 70 kilometres (44 miles) on battery power alone; this range is suitable for shorter routes but insufficient for longer journeys like the Crewe to Holyhead line.

Safety and Innovations in Battery Technology

The risk of lithium battery fires is relatively low, especially compared to petrol or diesel vehicles, but Hitachi has taken additional measures to ensure safety. The company uses Nissan Leaf cells, recognised for their strong safety record. However, lithium batteries can sometimes experience “thermal runaway,” where cells heat up uncontrollably if damaged. To address this, Hitachi equips each cell with a heat shield to contain potential fires and roof-mounted devices to actively cool the batteries. Advanced software also continuously monitors and regulates cell temperatures.

In an emergency, the most effective approach to extinguishing a lithium battery fire is rapid cooling with water. However, in confined areas like tunnels, managing smoke and toxic gases adds complexity to fire control. Hitachi’s design minimises disruption by ensuring that, even in the unlikely event of a battery fire, the train’s other carriages remain operational, allowing the train to continue moving safely.

Looking Forward: A Sustainable Future for Rail

Battery-powered trains represent a transformative step toward a greener rail system, aligning with the UK’s goal of reaching net-zero emissions by 2050. By reducing emissions and minimising noise pollution, these trains support cleaner and quieter communities. While hybrid models serve as a bridge to full electrification, ongoing advancements in battery technology are set to elevate fully electric trains to a central role in the rail network. Although challenges remain, improvements in battery capacity and charging infrastructure bring the widespread adoption of battery-powered trains within reach, paving the way for a cleaner, more sustainable rail industry.