An Independently Powered Electrical Multiple Unit (IPEMU) train

The new train on trial in Derby.

Trials of what is thought to be the UK's – and possibly the world's – first battery-powered train have begun by network operator Network Rail, with additional battery tests underway at the Bombardier Mannheim facility in Germany. 

A battery-powered train would not have to use diesel and could run on non-electrified track. Moreover, as the electricity grid is decarbonised with increasing amounts of renewable electricity, or if the batteries were charged from a renewable source, the battery-powered vehicles would become extremely sustainable.

For the trials, an Abellio Greater Anglia Class 379 unit, which normally operates using electricity drawn from overhead power lines, has been adapted with six battery rafts and is being tested on a test track in Derby in the Midlands. The tests, of what is being called an Independently Powered Electrical Multiple Unit (IPEMU), will culminate with a series of high-speed runs at the Rail Innovation and Development Centre in Nottinghamshire later this year.

The battery rafts fitted to the Class 379 unit contain a battery box containing a new type of lithium-ion battery (see below), isolation switch, power distribution control panel, battery charging inverter, batteries and battery monitoring system, all mounted within a bespoke, purpose-built rig. Their creation follows the successful testing of several types of battery technologies, including lithium iron magnesium phosphate and hot sodium nickel salt.

“We continue to test other possible solutions so we can gather as much information and comparison data as possible for future development,” said James Ambrose, senior engineer at Network Rail.

"If we can create an energy storage capability for trains, electric traction can be introduced to more parts of the network without the need to necessarily extend the electrification infrastructure," said Mr Richard Eccles, NR's director of network strategy and planning.

Data gathered during the experiment will be used to determine what form an independently powered electric multiple unit will take, be it a straight battery unit or hybrid.

Any future independently powered electric multiple would most likely be designed as a new train and not an adapted unit, to minimize energy consumption, but this project will also provide useful information for retrofit.


One of the partners in the project is FutureRailway, a body that has been set up by the UK rail industry to accelerate research, development and innovation to help it to deliver the government's Rail Technical Strategy (RTS), which aims to satisfy the increasing demand for rail services across the country as sustainably and economically as possible.

This includes efforts for reducing the environmental impacts rail travel, such as: noise and vibration, waste and pollution, sustainable consumption and production, air pollutant emission and biodiversity. A separate research stream is looking at measures to adapt rail transport to extreme climate change.

Large quantities of steel, concrete, aggregates and other materials are used for maintenance, renewal and enhancement of rail networks. Lower carbon options which do not adversely affect performance or cost could replace many of these materials. For example, using low carbon concrete which contains fly ash, a waste product from electricity generation and slag, a waste product from the steel industry, can reduce carbon life-cycle impacts by up to 80%.

Batteries for trains

Bombardier, which is testing the batteries, is a world leader in battery-powered and electric transport; so far mainly for buses, although it has developed a system for trains that uses ultracapacitors to store surplus energy. This 'MITRAC Energy Saver' enables light rail vehicles to economize almost one third of their energy consumption and also bridge patches without overhead lines. This system works by charging the ultracapacitors during vehicle braking, and releasing it when it is needed, such as when accelerating.

lithium iron magnesium phosphate batteries But the batteries (right) in the Network Rail trials are unique and of a novel design. Made by Valence in the US, they are a new generation of lithium iron magnesium phosphate batteries (unlike other litium-ion batteries), which were chosen after being tested in simulated conditions including intensive branch line journeys requiring eight hours of continuous operation, as well as range, speed and temperature tests.

Most lithium batteries (Li-ion) used in computer, communication, consumer electronics products are lithium cobalt oxide (LiCoO2). Other lithium batteries include lithium manganese oxide (LiMn2O4), lithium nickel oxide (LiNiO2), and lithium iron phosphate (LFP). The cathodes of lithium batteries are made with the above materials, and the anodes are generally made of carbon.

The advantages of the lithium iron magnesium phosphate intelligent battery modules are:

  • high cycle life
  • low total cost of ownership
  • no ventilation required
  • reliable electronics and firmware
  • safety
  • rugged mechanical design
  • flame retardant plastics and electronics.

The battery pack is scalable in series from 12V to 1000V or in parallel for additional run time and comes with automatic system balancing and monitoring.