Will battery driven trains be a reality soon?

Researchers suggest battery-powered trains could very soon be economically viable. A small team of researchers from Lawrence Berkeley National Laboratory and the University of California has found that battery-powered trains could become economical as soon as 2023.

A new analysis has looked at using batteries for trains. It finds that the technology is largely ready, and under the right circumstances the economics are on the verge of working. Plus, putting giant batteries on freight cars has the potential to create some interesting side benefits.

Right now, most freight in the US is moved by diesel-powered locomotives. In a typical year, these locomotives produce about 35 million tons of CO2.

Researchers have considered a few options for reducing train emissions. They could put poles with catenary wires along the tracks, but that would involve a significant construction cost and ongoing maintenance costs. It would also mean a significant outlay on new locomotives, with a pantograph car to draw the power from the catenaries to a transformer.

An alternative would be to supply the trains with fuel cells for hydrogen. This solution has the potential to be relatively cheap, but it requires the development of significant hydrogen production capacity, ideally by electrolysis with power from renewable sources. This capacity is probably many years away from becoming a reality.

The final option is to use batteries that could be integrated with the existing system. Most diesel locomotives use diesel to power an electric generator that provides power to the electric motors. A change in wiring could potentially allow locomotives to accept an external power source, such as a battery. A battery also makes it possible to harness braking energy to charge the battery.

Researchers investigated this possibility some years ago, but it was rejected for both technological and economic reasons. Since then, batteries have become significantly larger and have fallen in price by 87% over the last decade.

The analysis is based on a battery that has enough energy for a large freight train (four locomotives, 100 freight wagons and around 7,000 tonnes of payload). The battery is placed in a single freight car, and would take up only 40 percent of the volume of a typical boxcar, and would be seven tons below the weight limit imposed by existing bridges.

Because of the efficiency of direct electric power, the train would use only half the energy consumed by an internal combustion engine powering a generator. And while an average trip would not operate on a single charge, it is normal for a freight train to stop several times a day to change crews and refuel. Even short stops provide the opportunity to increase range with one charge. And if longer breaks are possible, the battery car itself can be swapped.

An added benefit of a running battery is that it can be relatively easily placed where backup capacity is needed in the grid, in combination with mobile solar cells they can also be used as emergency power systems. Because of the crazy system of floating prices for power depending on supply and demand, a large battery can pay for itself by charging when the price is low and selling when the price is high.

Read the full analysis in Nature https://www.nature.com/articles/s41560-021-00915-5