Research

Will “hydrogen trains” be able to rid us of diesel fuel?

When the UK government canceled itsplans to electrify rail lines through Wales, Midlands and the north of England reduced the electrification of the Great Western rail network, leading to a premature termination of the investment program in railways, which was considered one of the largest in the country since the Victorian era. But now the government and train manufacturers are hoping that hydrogen could be an alternative to electrifying British railways.

Hydrogen trains

Hydrogen trains have already replaced more dirty ones.diesel engines in Germany, and some railway companies believe the UK will follow suit by 2022. For the introduction of new technologies still need investment. But they can be an important step towards reducing the carbon footprint of railways.

Currently only one third is electrified.The UK railway network, and over the past few years, some additional railways have been converted. Stopping the electrification of the network, the government faces a dilemma: how to eliminate diesel trains that produce carbon dioxide and other harmful pollutants?

The current strategy is to buy bimodal trains that can switch to diesel when they get on their way without electricity. But this does not solve the problem as such.

If electrifying the rest of the networkwill seem too expensive, one of the possible alternatives is to generate electricity on board the train. One way to do this is to use fuel cells that combine hydrogen gas with oxygen from air to produce electricity and water. Hydrogen can carry more energy than batteries with the same weight, which means that fuel cell systems can be lighter. In addition, they require less time for refueling than batteries for recharging, and do not have the same high environmental costs during production.

Hydrogen gas must be compressed intanks, which are usually located on the roof of the train. But adding a regenerative braking system to charge an extra small battery will reduce the amount of hydrogen needed to power the train.

High cost of installing overhead wiresmeans that hydrogen trains are likely to be a more economical way to electrify rail lines with relatively little traffic. It also makes sense to experiment with hydrogen trains to identify any unexpected problems. However, widespread use will require significant investments in the production and storage of hydrogen. Since very few railways were built on a hydrogen base, it is not clear whether they can save money by refusing to electrify large lines or if an economy of scale will work.

The best solution may be to develop alsohybrid dual-mode trains that can switch between electricity from overhead wires and fuel cells. This is best suited for rail networks that run through bridges and tunnels.

Another hydrogen related issuefuel cells, is that fuel is now produced from methane (natural gas) using a process called steam methane reforming, which also gives a high yield of highly toxic carbon monoxide. It can be converted to carbon dioxide, but in this case hydrogen fuel will still contribute to greenhouse gas emissions.

Pure hydrogen

Environmentally friendly method of producing hydrogen -through electrolysis when an electric current is passed through the water. Theoretically, it is possible to use excess wind energy (and, possibly, the sun) to generate this electricity and make hydrogen a renewable source of energy. The problem is that electrolysis plants are unlikely to be economical if they do not work most of the day. This will mean that when there is no excess wind to power them, they will need regular electricity from the network, which will make the process very expensive (and not necessarily renewable).

The second alternative is to use"Thermochemical" production method, which includes the interaction of water with sulfur and iodine in the presence of heat. The good news is that this method will become economical over the next ten years, thanks to the development of nuclear power plants of the fourth generation. These high temperature small modular reactors are being developed in China, the USA, Canada and Japan, but not in the UK or Europe.

Despite all limitations of usehydrogen as a transport fuel, as more and more countries (particularly Japan) are conducting further research on the hydrogen economy, its cost will decline. Hydrogen can even replace the natural gas in the main gas pipes, which will also help reduce the cost of its use for transport.

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