The rail industry stands at an important crossroad today, and everybody is in the process of looking for means of reducing pollution, improving efficiency, and employing clean energy such as solar and wind power. Among the very promising solutions are energy storage systems, which let trains and rail networks “catch” and store energy that otherwise would be dissipated and use it again.
Specifically, there are two ways: one is to install the energy storage system next to the track and the other is to install it directly on the train. Both technologies are quietly changing the future of rail transportation. Not only can they help us save money, but they can also reduce carbon emissions, make our environment cleaner, and make the railway’s power supply system more stable.
Why Energy Storage Matters for Railways
Although the railway is a very energy-saving way of transportation, it still depends on the supply of traditional power. The regenerative braking technology can transform kinetic energy into electrical energy in the process of slowing down of the train, which is an excellent opportunity to recycle energy. Unfortunately, with the lack of a suitable energy storage system, most of this electricity will be wasted and dissipated as useless heat.
In particular, one recent research in the Renewable and Sustainable Energy Reviews has pointed out that if energy storage technology is utilized in the railway system, it is possible to recover up to 21% of the generated power. This way, the railway will require much less electricity from the grid. This would not only save a lot on operating costs but also make the energy supply far more stable and much more environment-friendly.
Types of Energy Storage in Railway Systems
There are two primary ways energy storage systems can be incorporated into rail networks:
1. Onboard Energy Storage
This setup allows trains to store the energy they generate and reuse it for acceleration, reducing reliance on external power sources.
✔ Advantages:
- Immediate energy reuse reduces electricity consumption.
- Ideal for metro and commuter trains with frequent stops.
- Enhances energy efficiency in hybrid and fully electric trains.
❌ Challenges:
- Adds extra weight, increasing overall energy demand.
- Reduces available space for passengers or freight.
For example, the Shinkansen N700S of Japan is the first high-speed train fitted with an onboard battery energy storage system that will allow the train to continue running during a power cut.
2. Trackside Energy Storage Systems (ESS)
Also known as wayside ESS, these stationary storage units are positioned alongside railway infrastructure to capture excess energy from trains and redistribute it where needed.
✔ Advantages:
- Eliminates the need for heavy onboard batteries.
- Provides power for multiple trains across the network.
- Can integrate with renewable energy sources like solar and wind.
❌ Challenges:
- Requires significant investment in infrastructure.
- Optimal placement is crucial for maximizing efficiency.
Cities like Madrid and Cologne had been able to use supercapacitors that have held electrical storage well; London Underground is even trying the usage of a flywheel mechanism, which worked really efficiently with electrical discharge and accumulation.
Which Energy Storage Technology Works Best?
Depending on the type of railway system, different energy storage solutions may be more suitable:
Lithium-Ion Batteries – High energy density, widely used in hybrid and fully electric trains. Best for onboard storage due to their lightweight and rapid rechargeability.
Supercapacitors – Deliver quick bursts of power, making them ideal for regenerative braking. Deployed in multiple metro systems worldwide.
Flywheel Energy Storage – Captures kinetic energy efficiently and is commonly used in trackside ESS solutions. This low-maintenance, high-efficiency technology is gaining traction in long-distance rail applications.
Real-World Applications of Railway Energy Storage
In fact, many railway systems in the world have already applied energy storage technology with good results:
Tokyo’s railway is powered with onboard energy storage for better energy efficiency.
Once, the London Underground tried to apply flywheel energy storage for driving trains.
Madrid and Cologne have utilized supercapacitor energy storage to great advantage, which captures excess energy during braking and reuses it.
The SunTrain project in the United States transmits stored solar energy in batteries for over 6,500 miles through the Union Pacific Railway network.
These examples show that energy storage can make rail transportation both greener and cheaper.
The Future of Energy Storage in Railways
The energy storage system for railway electrification will be increasingly important in the near future because of the increasing interest in using renewable sources of energy like solar and wind power. Imagine in some years to come that the entire running of the trains can be powered by solar and wind, and extra generated electricity is stored in energy storage systems beside the track until needed.
Is this going to completely change the use of renewable energy with battery-powered rail cars? A number of companies have begun to study the idea, further blurring the line between transport and energy storage.
With the continuous development of Flywheel energy storage technology, lithium-ion batteries, and supercapacitors, the greener, smarter, and efficient direction of the railway industry is unveiled.