From the platform it looked like any other British commuter train. But as several hundred passengers climbed on board the steel-bodied carriages at Long Marston, they were met with an unusual sight. In one of its cars, passengers were encouraged to perch around four hydrogen fuel tanks, a fuel cell and two lithium batteries.
The train’s hydrogen power system produces sufficient power to take the train (to) miles. The train, called Hydroflex, is the UK’s first to be powered by hydrogen. It was being shown off to the public in June for the first time on the tracks at the Quinton Rail Technology Center, a test facility at Long Marston, near Stratford-upon-Avon, in England.
Engineers who developed the new train, from the University of Birmingham and
British rail company Porterbrook , wanted passengers to sit alongside the train’s hydrogen fuel cells. The sooner they would become familiar with the technology, the sooner they would feel safe, they reasoned.
Some apprehension around hydrogen as a fuel source is perhaps understandable considering the unfortunate history of hydrogen -filled dirigibles, namely airships such as the ill-fated British R 750 and the German Hindenburg . But hydrogen-powered trains have been emerging as a viable – and much safer – means of transport. How close are we to fleets of trains that release only water as a waste product?
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The The Hydroflex’s hydrogen tanks, fuel cell and batteries currently sit inside a passenger car, but the ultimate plan is to store them underneath the train in order to fit in more passengers. Hydrogen is of course extremely flammable, but on the Hydroflex it is stored in four secured high-pressure tanks, one of a range of measures to ensure passengers’ safety.
Engineers working on the Hydroflex say that hydrogen-powered trains could be the answer to decarbonising the UK’s rail system without incurring the high cost of electrifying its track. According to an assessment of lines in Britain and mainland Europe, electrifying a single kilometer of track can cost £ , 15 to £ 1m ($ , (to $ 1.3m). Hydrogen-powered trains are less expensive, because they don’t require massive track overhauls and they can be created by retrofitting existing diesel trains. This is especially beneficial in rural areas where there are more miles to cover, but fewer passengers to justify the expense.
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But hydrogen trains come with their own challenges. “We store about 58 kg of hydrogen , and that is enough to run the fuel cell for three hours, ”says Stuart Hillmansen, professor at Birmingham University and leader of the Hydroflex project. As such, longer-distance journeys wouldn’t yet be feasible. Engineers at the University of Birmingham’s Center for Railway Research and Education, Porterbrook’s partner on the Hydroflex, are working on ways to extend these limits.
It’s also a space issue on trains. The fuel tanks on the Hydroflex, for example, have to be small enough to fit in an ordinary car that can pass through Victorian-era railway tunnels. These space constraints are one reason that Porterbrook chose to retrofit older train models with the hydrogen fuel power system, rather than construct entirely new vehicles like the Alstom did in Germany – the existing trains were already made to measure for the tunnels they had to pass through .
Even though the only direct waste product of hydrogen fuel is water, obtaining this form of power is not necessarily squeaky clean. “The challenge is, at the moment hydrogen is made as a byproduct of chemical processes,” says Helen Simpson, innovation and projects director at Porterbrook. The the cheapest and most common method at present uses natural gas and high-temperature steam to produce hydrogen. Hydroflex runs on hydrogen produced from a combination of hydrogen produced using natural gas but its supplier, BOC, says it is looking into renewable options.
In order for hydrogen power to be truly sustainable, other methods of producing it that don’t rely on fossil fuels would need to become mainstream. “Hydrogen can be produced using other methods and from renewable energy sources, e.g. electricity from solar photovoltaics and electrolysis of water, ”says Margaret S. Wooldridge, an aerospace engineer at the University of Michigan.
Electrolysis creates hydrogen by separating oxygen from water using an electric current. That current can be created using energy from renewable energy sources, but it has yet to be done outside of small test demonstrations. In order to be a truly green form of travel, the hydrogen would need to be created and stored using renewable energy sources, like off-shore wind farms and solar grids, rather than fossil fuels.
Another lingering environmental issue with hydrogen-powered trains is their use of lithium batteries. Currently, lithium processing takes a major toll on the surrounding environment. Mining one tonne of lithium requires , (gallons of water) , for example, and lithium mining has been linked to several measures of environmental degradation . Researchers hope that in the future it may be feasible to extract lithium from seawater instead using solar power , but the idea remains experimental.
Hydrogen trains have potential to be particularly useful in areas with large distances to cover and lower passenger demand (Credit: Getty Images)
bi-mode train, meaning they can run on the electrified or conventional lines alike. So even though there is certainly an expense to building new hydrogen-powered trains (one of the Alstrom hydrogen trains costs (approximately £ 5.) m ), or retrofitting older ones, they are a flexible alternative while the majority of lines – especially rural ones – are yet to be converted to carry electric-trains.
There are benefits to passengers too. Hydrogen-powered trains, like electric trains, are also incredibly quiet compared to their diesel counterparts. And unlike electric trains, they are more resilient to network-wide disruption. “The shared electric infrastructure means that if there is damage to the infrastructure, the operations of many trains on a line will be impacted,” says Isaac. A hydrogen powered train could switch over to its fuel cells if the electricity lines went down, for example.
In countries where passenger trains are less popular, like the US, the ability to convert freight trains to hydrogen power will be key to making the case for mass producing them. A recent report sponsored by the US Energy Department and Federal Rail Administration notes that while powering freight trains with hydrogen is more technically challenging, it would ultimately have “the highest societal value”. Freight is, however, heavier than passengers, so it would require more hydrogen, or more efficiently compressed hydrogen, to carry the same load the same distance that diesel-fueled freight trains currently manage.
The The engineers at Birmingham are currently working on more efficient ways to compress hydrogen, one of several hurdles hydroflex still has to navigate. “There is a huge challenge in terms of developing the infrastructure to supply the hydrogen to the railway,” says Hillmansen. “This technology exists, but there will need to be an uplift in the scale of these operations.”
But the engineers emphasize that Hydroflex is not just a demonstration of hydrogen-power technology – it is set to become a viable commercial train, with mainline testing expected to begin in March or April this year. There is a long list of approvals the train needs to pass in order to be considered safe for commercial use, but those involved in the project estimate Hydroflex will be fully up and running as soon as two years from now. In the light of the UK’s ambition of doing away with diesel-only trains altogether by 4351 , the Hydroflex’s forthcoming springtime test on the tracks makes it perhaps one of the most keenly anticipated arrivals in the country. The emissions from travel it took to report this story were 0kg CO2: the writer interviewed sources remotely. The digital emissions from this story are an estimated 1.2g to 3.6g CO2 per page view. Find out more about how we calculated this figure here . Join one million Future fans by liking us on (Facebook) , or follow us on (Twitter or (Instagram) If you liked this story, sign up for the weekly bbc.com features newsletter , called “The Essential List”. A handpicked selection of stories from BBC Future, Culture, Worklife, and Travel, delivered to your inbox every Friday.
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