Will Most Trains in the Future run on Electricity?

By Noel T. Braymer

Technically most trains already run on electricity. Diesel-electric locomotives use a diesel engine to generate electricity to power the electric motors in the locomotive’s trucks. The question is will trains continue to be powered by fossil fuels?  The cost of energy is a big issue for train operators. In North America there are plans to change over to diesel locomotives fueled by Liquid Natural Gas. With Natural Gas currently much cheaper than diesel fuel this seems to make a great deal of sense.

But this is easier said than done. This will require major changes in the equipment used by the railroads and will be a major investment. Liquid fuel is the most efficient way to carry enough energy to run trains a long distance. But liquefying Natural Gas requires refrigerating it by hundreds of degrees below zero. This is not cheap and requires a great deal of energy to do.  Also new facilities will needed to fuel trains with Liquid Natural Gas and a reliable way to carry it on trains will be needed. The plan is to build “tenders” to carry the Liquid Natural Gas for the locomotives on a freight trains. A recent news story run by Reuters reports that after a year of experimenting with running trucks with Liquid Natural Gas; the Canadian Trucking Company Bison Transport found the savings less and the problems more than expected.

Liquid Natural Gas has long been seen as the solution to transporting Natural Gas economically. As a gas it can only be economically transported by pipeline. Pipelines are generally built on land and it is not economical to build pipelines long distances underwater. But many places in the world have surplus Natural Gas which they can’t build pipelines to major markets overseas such as the Middle East to Europe. Despite years of trying, shipping Liquid Natural Gas has not been a major success. A few years back there was an attempt using the technology used by Germany in World War II to make gasoline from coal to turn Natural Gas into diesel fuel. This would be a liquid fuel easily shipped by tankers to take make use surplus Natural Gas. This project was eventually shelved.

What is certain is the price of electricity from solar or wind power is going down and will continue to go down. The price of solar and wind powered electricity has dropped so much recently that in many markets such as in California it is competitive with the cost of electricity from fossil fuels. Based on current trends in about 10 years solar and wind power electricity will be cheaper than electricity made with Natural Gas in most of the world.

Not only is the cost of making electricity getting cheaper with solar and wind, but so are the ways of storing electricity. Recently there was a news story of research on a new capacitor using nanotubes and graphene which would be cheap to make yet store large amount of electrical energy. Capacitors can be charged and discharged with electricity rapidly.

There is also constant progress making batteries cheaper, lighter and holding more power. The next generation of batteries being developed now are metal-air batteries. Batteries are made of anodes and cathodes. In a metal-air battery, a metal such as lithium, aluminum, or zinc would be used as the anode with oxygen from the air being the cathode. This battery can be built with a lighter casing and doesn’t need to carry the weight of a chemical cathode. This results in a much lighter battery with more energy than current ones. These batteries are expected to be competitive with internal combustion engines operationally but with lower costs.

The problems to be solved before mass production of metal-air batteries are possible are filtering carbon dioxide out of the air and making metal-air batteries rechargeable. One company claims to have done both. Phinergy claims that they have developed a filtering system to remove carbon dioxide from their metal-air batteries. Carbon dioxide greatly reduces the life of metal-air batteries. Phinergy has developed an aluminum-air battery which they have tested in an electric car and drove for a thousand miles. This battery is not rechargeable, but the aluminum from this battery is recyclable and can be replaced. Phinergy plans to go into mass production on this battery by 2017. They claim to also have developed a rechargeable zinc-air battery. Many other companies are also working on metal-air batteries, so it is likely we will see other advanced metal-air batteries on the market in less than 5 years.

What we could see in the near future are  plug-in hybrid locomotives. The main use of energy in all transportation is from acceleration and climbing. Particularly with a train, once it is up to speed it doesn’t need a great deal of energy to keep going with the low friction of steel wheels on rails. With a hybrid system batteries or capacitors could store power to give an extra push during acceleration and climbing hills while a small generator can keep the batteries or capacitor topped off and provide the power to run the train when cruising. Using the train’s regenerative brakes, a hybrid locomotive could recycle energy into storage from braking to a stop or when going downhill. Hybrids save energy and reduce emissions, both of which the railroads want.

Hybrid locomotive could also have pantagraphs, which would allow them to operate on electrified segments of railroads while having the flexibility of operations in branches without electrification. With cheaper, cleaner electricity coming in the near future, this will likely spur increased electrification of the railroads. Not only will electricity be cheaper in the future, but increasingly more people and businesses are making their own to save even more. Railroads and rail operators have land to place solar panels and windmills to make their own electricity. While the cost of electrification isn’t cheap, being able to save money on electricity compared with fossil fuels will make the capital costs of electrification more attractive. Electrifying the railroads could earn them revenue from selling surplus power to the grid.

It is always difficult to predict the future, even of technology. We are still waiting for our hovercraft cars and personal jet packs. But future reductions in the cost of electricity with renewable power is certain. With it we will likely see more trains run with the help of stored electrical power and electrification.

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