If we look at the past of a train, from a coal engine to an electric engine, they have come across a long journey. Now it’s time again to move forward and change the future. Engineers from the University of Birmingham and British rail company Porterbrook, made a train which runs on hydrogen.
The train’s hydrogen power system produces sufficient power to take the train 50 to 75 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 2019 for the first time on the tracks at the Quinton Rail Technology Centre, a test facility at Long Marston, near Stratford-upon-Avon, in England.
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 R101 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?
How it is made?
The way hydrogen powers a train like the Hydroflex is quite simple. The fuel cell is made up of an anode, a cathode and an electrolyte membrane. The stored hydrogen passes through the anode, where it is split into electrons and protons. The electrons are then forced through a circuit that generates an electric charge that can be stored in lithium batteries or sent directly to the train’s electric motor. The leftover part of the hydrogen molecule reacts with oxygen at the cathode and becomes the waste product – water.
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.
Helps in decarbonisation
In the midst of the climate crisis, the demand for decarbonisation across transport industries has grown and the Hydroflex is just one product of that. In 2016, Germany unveiled the Coradia iLint, the world’s first hydrogen-powered train, which can run for 600 miles on a single tank of fuel – on par with the distances that traditional trains achieve on a tank of diesel. Engineers in the US are also working on bringing a version of a “hydrail” to the states. However, since rail is already among the lowest greenhouse gas emitters in transportation, it remains to be seen whether the value of a massive overhaul of rail systems will be worth it.
The Fact
The UK already has 42% of its route miles electrified, according to the Institution of Mechanical Engineers, meaning those trains are ready to become zero-carbon, if they use a renewable source of power. A single line running to London from Hampshire is currently the only one in the world of run solely on solar power. However, the remaining 58% of UK track is not yet electrified, so diesel trains are still needed to keep those areas connected by rail.
Cost effective
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 20 lines in Britain and mainland Europe, electrifying a single kilometer of track can cost £750,000 to £1m ($965,000 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.
There are challenges too
Hydrogen trains come with their own challenges. “We store about 20kg of hydrogen, 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 Centre for Railway Research and Education, Porterbrook’s partner on the Hydroflex, are working on ways to extend these limits.
And while hydrogen fuel cells can be as energy-efficient as diesel fuel, storing the gas can be a problem. “While hydrogen has a lot of energy per mass, because it is super light, it also takes up a lot of volume,” says Raphael Isaac, a researcher on fuel alternatives in rail at Michigan State University’s Center for Railway Research and Education.
“With our current hydrogen storage technologies, hydrogen takes up significantly more space than [equivalent] fossil fuels do.” Even though hydrogen is typically compressed, it’s still not as efficient per unit volume as fossil fuels.
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 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 cheapest and most common method at present uses natural gas and high-temperature steam to produce hydrogen. Hydroflex runs on a 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.
