In the US, the typical freight car travels an average of 241 kilometers per day when in operation. So the researchers created a battery big enough to move that distance as part of a large freight train (four locomotives, 100 freight cars, and about 7,000 tonnes of payload). They found that lithium ferrous phosphate would let each of the four locomotives be serviced by a single freight car configured as a giant battery. The battery would only occupy 40 percent of the volume of a typical boxcar and would be seven tonnes 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 driving an on-board generator. And while an above-average trip wouldn't work on a single charge, freight trains normally stop several times a day to change crew and refuel, providing an opportunity to boost the range with some fast charging. And if longer breaks are possible, the battery cars themselves could be swapped out.
While the system wouldn't require new locomotives, the batteries and charging infrastructure it would need make for some substantial up-front costs. The researchers added up all these costs and then calculated the price of electricity that would be needed to make the whole thing price-competitive with diesel.
Can we use big batteries to power our trains? | Ars Technicahttps://arstechnica.com/science/2021/11/can-we-run-our-trains-using-big-batteries/