Most intercity trains run on diesel power which was an improvement over coal, but still is a serious pollutant. Inner-city services mainly draw their electricity from overhead power lines instead. This is an improvement, although that electricity may come from a polluting source. Batteries are the way to go forward but their capacity is limited. We explore the contribution of tri-mode battery electric trains as an interim measure.
The Power That Drives The Train Wheels is The Key
Most diesel locomotives don’t power their driving wheels directly. Instead, their diesel motors power generators that send the electricity to the bogies. This is why battery-electric trains seem such an obvious alternative at first sight.
In theory, we simply replace the diesel motors, or overhead power lines, with batteries and the job is done. However, the catch is half the carriages would be full of batteries. This solution is neither cost-effective nor practical.
We Would Need Tri-Mode Battery Energy To Close The Gap
Many rural areas across the globe still rely on diesel electric locomotives to power their rail transport. However, as their motors age, their operators are seeking more environmentally-friendly ways to turn the wheels.
BBC News channel reports on an interesting offering from Hitachi Rail. This company has an innovative suggestion which might solve some of the challenges facing United Kingdom’s aging rail network:
- Replace one diesel generator on each train with lithium battery packs.
- Use tri-mode battery electric power where there are no electrified tracks.
- Recharge the batteries from mains power when this is available again.
Engineering News predicts this arrangement could halve diesel fuel consumption, and emissions.
How a Tri-Mode Battery System Would Work in Practice
These systems would be interim measures while rail transport waited for battery storage capacity to catch up. The batteries would seamlessly take over from the diesel electric generator, as the train entered an urban area.
The train would glide to a silent halt at the station. The battery would power the train as it left until it reached a rural area again. At that point the diesel might take over, but only for the time being.
More Information
Great Western Railway Battery Train Record
