In November last year, Alstom – the first company to deploy a hydrogen-powered passenger train, with the Coradia iLint entering service in Germany in 2018 – reportedly paused development of its hydrogen trains after French funding was withdrawn, with CEO Henri Poupart-Lafarge reported to have said the technology was “not yet mature”.
In the UK, there are few signs of any imminent deployments, despite development and testing of a hydrogen-ready passenger train. But while the future of hydrogen in passenger rail looks somewhat uncertain, that is not the only potential application for the zero-emission fuel. It could be a promising option for freight, according to Paul Long, head of traction and rolling stock engineering at freight company Heavy Haul Rail (HHR), formerly part of Freightliner.
Some factors make freight particularly well-suited to hydrogen, said Long, such as its proximity to likely production locations at ports and energy facilities, and the potentially straightforward options for replacement of diesel engines, which are valued for their power density and effectiveness.
There are three main options for hydrogen technologies, he said: fuel cells, as seen on the iLint and in projects such as the HydroShunter from Vanguard Sustainable Transport Solutions; internal combustion engines, which are potentially lower risk thanks to their similarity to diesel, and in development at companies including BeHydro in Belgium; and ‘green steam’ generators coupled with turbines, being developed at Steamology in Wiltshire.
Although the products are not necessarily commercially available, Long told Professional Engineering that the “‘powering the loco’ bit is fine”: “There are understood technologies that could do that. The barrier with hydrogen is just storage.”
That is a fairly major barrier. While freight locomotives currently use fuel tanks with 5,500-6,500 litres of diesel, hydrogen could require eight to 13 times that volume, according to Long. That would require a high-pressure tank wagon, he said, as “there’s no way you would ever get that size of hydrogen into the locomotive”.
Unfortunately, freight trains are already pressed for space. Roughly three-quarters of HHR trains are at their maximum length already, Long said. “If you now need a tank wagon full of hydrogen, you’re effectively removing revenue-earning wagons that consist in order to save the hydrogen. So you’ve got to accept – or there has to be some way in which you can offset – that hit you’re taking in your margin, and your productivity, in order to carry that hydrogen around.”
Denser storage options, such as tanks containing metal hydrides, could provide some solutions in future, although technical questions remain to be solved.
For now, hydrogen is too expensive to be practical – but if the government maintains its hydrogen ambitions and offers subsidies for its use as a fuel, it could become a practical alternative to electrification as emissions are cut from the network ahead of the 2050 net zero target.
“Electrification is brilliant, but the rate of rollout… is the major issue,” said Long, who is presenting an IMechE seminar on freight on 16 September. “To meet the government targets, even of 2050, I think it’s implausible to believe that other options won’t be required above and beyond electrification.”
Batteries might look like another option – but, Long said, they have similar volume and density issues to hydrogen, and the amount required could weigh about 100 tonnes. Unlike lighter hydrogen, that weight would remain the same for an entire journey.
If the government backs up its hydrogen aims, with widespread production and new distribution methods, it could become practical for freight. Shunting – moving rolling stock around yards, depots or stations – could be practical even sooner.
Birmingham firm Vanguard showed what that future could look like last month in Kidderminster, where its zero-emission HydroShunter hauled a carriage carrying people along over a kilometre of track. The prototype is a ‘retractioned’ Class 08 shunter, which was being “slowly harvested for parts” until CEO Dr Alex Burrows had the idea of fitting it with a hydrogen-battery power pack, according to Vanguard’s chief innovation engineer Dr Charles Calvert.
Originally built in 1959, the Class 08 gained a new lease of life from a hydrogen fuel cell, storage tanks and a lead acid battery, all of which work together in place of a diesel engine and generator.
“In concept, it’s very, very similar,” said Calvert, who is also a co-founder of the company. “Via DC-to-DC converters, we take the power output from the battery and from the fuel cell and provide the traction motors with the volts and amps that they’re looking for at any particular time. And that drives the shunter; that makes it go.
“Performance is equivalent to a factory-fresh Class 08 – and, trust me, at this stage in their life, they are not factory-fresh anymore.”
Developed for several years before the recent demonstration, the HydroShunter has also moved 80-tonne and 120-tonne locomotives around the Kidderminster yard.
“We’re building up, step by step, the amount of weight that we’re testing it with… getting really, really confident with the system as we de-snag stuff and really look to expand to its full capabilities,” Calvert told Professional Engineering.
The final product will be a locomotive-agnostic power pack known as Neo, designed to replace the prime mover in a variety of rail vehicles. “We’ve started with about as small a locomotive as you can, but the concept does scale. You need more power? You add more fuel cells, you add more battery or you change the battery chemistry,” the innovation engineer continued.
The company uses green hydrogen generated using renewable energy, while the fuel cell-battery combination causes much less noise pollution than diesel, further boosting its environmental credentials. The most significant aspect for prospective users would likely be the opportunity to turn obsolete vehicles into ‘like-new’ machines, however.
Unlike freight, where operators are wary of committing while fuel prices are high and uncertainty remains over future government backing, Long said shunting would be a “far easier” application. “It doesn’t use as much power, obviously, because you’re low speed and you’re doing smaller moves in the yard.”
Shunting could show an immediate route forward for hydrogen in rail, Calvert said. “Typically, for a passenger train, you need a fleet – you need to have multiple trains operating, all standardised, so the maintenance demands are all the same, logistics demands are all the same,” he said.
“Quite often, just a single shunter gets dropped at a location… A customer could say to us: ‘We want one’. They’re not going to say: ‘We’re not interested unless you provide five’ – which means that it’s much more of a ‘toe dip’.”
He concluded: “It is the first step for a new railway traction technology… one that can come into use in the very, very near future.”
Want the best engineering stories delivered straight to your inbox? The Professional Engineering newsletter gives you vital updates on the most cutting-edge engineering and exciting new job opportunities. To sign up, click here.
Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.