Hydrogen can be the number one for tomorrow’s railway

Diesel is dirty. And electric expensive. This gives rail a problem.
What fuel should tomorrow’s trains burn? After decades wedded to diesel it seemed that rail was about to break into a new world of clean electric trains. That was before Network Rail started erecting masts and wires along the Great Western and found the whole enterprise taking far longer and costing far more than it had anticipated.
NR’s problems were starkly illustrated on October 10 when train operator Great Western Railway revealed that it was facing an emergency closure at Reading over the following weekend to allow NR to test overhead electric lines. GWR’s announcement came on the same day that NR ran a special inspection train to show off its work to journalists. It prompted Andrew Adonis – the minister who announced GW electrification back in 2009 – to comment that such a train was his idea of heaven. “Problem is, it will make me angry to see the mess [NR] made of Great Western electrification,” he added.
Faced with NR’s rocketing costs, it’s no surprise that government in London had second thoughts. I’ll win few friends by trying to defend Chris Grayling but what was he to do in the face of rising bills and slipping deadlines? Shovel more money towards NR at a time when money across government is tight? Or risk wrath by cancelling further wiring projects? He chose cancellation and at the same time talked about alternative fuels.
Cancelling projects forces the railway to think again. NR needs to think again about how it can deliver an electric railway for much lower cost. After all, the idea of electrifying a route is to make it cheaper to run. No business will survive by making its product more expensive unless that product is clearly better. Electric railways should provide faster journeys because their trains are more powerful than diesels. Or they could use the extra power to run longer trains and provide more seats.
Rail companies should consider the words of one senior engineer, Peter Dearman: “The art of a good engineer is to do for 50 pence what any idiot can do for a pound.”
In essence, Grayling is telling rail companies to go away and look again at what they’re proposing and the costs attached to it. I don’t believe he doesn’t like electrification on principle, he just doesn’t like being presented with unexpected bills. And he’s probably right when he suggests that passengers don’t particularly care what powers their train. They care that it’s reliable and affordable.
What then of the other part of his summer announcements, alternative fuels? In the short-term, this can only be diesel, which is hardly alternative for an industry that embraced if from the 1950s as it weaned itself from even dirtier coal. Diesel is also the fuel that Grayling’s Department for Transport is doing its best to remove from our roads because it believes it’s too polluting.
It’s polluting on rail too as Christian Wolmar rightly said in RAIL 837. What’s the alternative?
Perhaps it’s hydrogen? You might be sceptical, I certainly was before doing some digging. Yet a locomotive powered by the gas ran in Britain five years ago. Birmingham University built it to compete in the Institution of Mechanical Engineers’ inaugural railway challenge at Stapleford’s miniature railway. Since then several more have run.
Fuel cells on board the machine took hydrogen and air and converted it to water and an electrical current. The current powered the train and the water was a harmless byproduct of the process. Since then, Alstom has been testing a full-size multiple unit in Germany that is powered by hydrogen fuel cells. This unit also stores power recovered from braking in batteries so that it can be used to boost that coming from hydrogen. Alstom’s train is based on an established DMU design.
Britain faces a glut of redundant electric multiple units (EMUs) following recent franchise awards that have pledged new fleets. This provides plenty of scope for an enterprising company to invest in hydrogen fuel cell technology and convert an EMU into an HMU (or an electro-hydrogen bi-mode unit). Porterbrook is already converting Class 319 EMUs into hybrid units with diesel engines. Adding hydrogen power to an EMU is the next natural step.
Such a train may produce no pollution in its immediate surroundings but that doesn’t mean hydrogen has no pollution bill. It depends on how it’s produced. It might be a very common element (it’s part of water after all) but as a fuel it must be produced from something else, just as electricity is.
Natural gas can be one feedstock. Fed into a steam methane reforming (SMR) plant and the result is hydrogen and carbon dioxide, a greenhouse gas. Most depots already have a gas supply so this could be one practical method of supplying hydrogen for trains. But the carbon dioxide gives SMR plants a problem.
The other option is to use electricity in a reverse of the fuel-cell process. If your electricity comes from renewable sources then you can claim your hydrogen is a green fuel. Otherwise, there will still be environmental emissions but they’ll be at some distance from depot or train.
This raises an interesting prospect of electricity from solar or wind farms being used to generate hydrogen that’s used to refuel trains overnight. It would cement rail’s position as the greenest way to travel.
Rail could banish sooty trainsheds and consign to history smokey DMUs accelerating from stations – in-short, create a clean railway that previous generations would barely recognise.
Whatever its source, on the train hydrogen will flow into stacks of hundreds of individual fuel cells. The power these stacks pack can vary between 70kW and 200kW and they can be combined to give more power, according to Birmingham University researcher Andreas Hoffrichter, who wrote his PhD thesis in 2013 on hydrogen trains. They have a lifespan comparable to DMU engines and Hoffrichter’s theoretical work suggested a hydrogen MU would be capable of the same daily duties as a DMU.
He found them to be more efficient (40%) on-rail than diesel trains (30%) but less than electrics (76%) but heavier, doubtless with the weight of the 350-700 bar gas tanks a major factor. In a computer-modelled run between Birmingham and Stratford the HMU emitted 862kg of carbon (on a well-to-wheel basis, so taking into account that his hydrogen came from natural gas) and his DMU emitted 1,895kg.
Those figures might be from modelled rather than real journeys but there’s sufficient difference in them to suggest that hydrogen is very likely to be real contender to replace diesel for environmental reasons.
What’s needed now is a real train and real tests. Let’s use at least one of those redundant and otherwise wasted EMUs to push technology forward and wean the railway from diesel.
It’s easy to scoff at Chris Grayling’s ‘alt-fuel’ comments but it’s in the railway’s power to do something about it. Let’s see who’s prepared to make a difference and take the railway forward.

This article first appeared in RAIL 838, published on October 25 2017.