The Coming Rail Revolution

Diesel trains are wonderful. No really, truly wonderful things. You can get enough power out of a diesel engine for most applications, the fuel is readily available and quite cheap, and, while they don’t quite have the captivating power of a steam engine, old diesel locomotives do still command attention among enthusiasts.

That is not to say, outside of the spheres of operational convenience and trainspotting, they don’t have their problems. No doubt you, dear reader, will have heard of the dieselgate scandal at Volkswagen, and you were probably also unsurprised to learn of the various Sulfur and Nitrogen based pollutants that stem from diesel engines. Perhaps, with some astonishment, or a sense of unsurprised resignation, you may have learned of the quality, or lack thereof, of the air in the cities of the UK. Yes, we learn that the air quality in the great cities of this nation is far worse than the limits set by both the UK and many other organisations, including the EU.

Of course, this is a difficult issue of modern times, and if we are being honest, the main culprit is most likely the proliferation of motor vehicles powered by fossil fuels. I confess that this is not my area of expertise, but for some more detailed commentary on the issue, I refer you to my article on cars, which can be found helpfully here.

But, my dear reader, we should not be complacent about the railways, and our aforementioned diesel trains. Though, due to the low-friction nature of the steel wheel on steel rail system on which railways work, the energy consumption of a train per passenger is lower than a car, we should perhaps give trains a lower priority, this is no excuse, as I shall now explain.

You may have noticed shiny new Tesla cars appearing on the roads, or perhaps on television. If you haven’t seen one of these fine new American machines, you may well have seen a different kind of electric automobile, a Nissan Leaf maybe, or a (fairly odd-looking, if I may say so) BMW i3, or some kind of Toyota hybrid car. What they show is that the electrification of the roads is coming, or rather, it is already happening, and it even extends to motorsport, with Formula E. This could, with time, reduce the harmful emissions, of the automobiles themselves that is, to nothing.

Not content with the electrification of private transport, the inventive Mr Musk has decided to extend this potentially life-saving innovation to the complex world of road freight. He has devised this electric truck, that he claims at least will do 300 miles on a single charge, and 500 for the top model. Now I am not going to try and argue that this is a bad thing, as in itself this is rather good news, particularly for those living near main roads, but I am slightly worried about this development. I am not concerned, dear reader, about the issues of building such large batteries, and the environmental problems thereof, though that is a valid concern.

No, I am concerned because this makes us in the rail camp, frankly, look bad. At the moment, rail freight is much more environmentally friendly than the equivalent road freight. After all, one lorry can take only one shipping container, whereas one train can carry over 30. The low steel wheel on steel rail friction also reduces the energy consumption per container, so on the assumption that both modes (road and rail) are using diesel engines, rail is going to result in lower overall emissions. However, with the road freight electric, this is turned on its head, as the rail option is still producing emissions.

Now I shall grant myself, and the others in the rail camp, the small comfort that some of the main lines in the UK are electrified, generally using overhead live wires from which the trains can draw power. The unfortunate fact is that most of the ports and freight terminals are not electrified, leaving the freight operator with two options:

i) Change the locomotive from diesel to electric when the train reaches the main line

This is possible, and used to be reasonably routine. It is a solution, dear friends, not without its problems. On the contrary, you have complications with where to change locomotives, and store them when not in use. You also have the obstacle of how to fit in all the associated train movements on an increasingly crowded network. As such, that leaves us with…

ii) Run the train with a diesel locomotive all the way

Far too often, this is what actually happens, even when the distances “under the wires” are hundreds of miles. All the same, as I am sure you are aware, this does bring the problem of emissions.

So a solution that reduces, or preferably eliminates, the emissions of freight locomotives, is needed.

Earlier I mentioned the various electric automobiles that are beginning to furnish the driveways of fine, upstanding UK citizens. This brings me onto the subject of passenger transport, and here again, railways are in a spot of bother. You see, there are many routes on which there is no electrification, particularly in the North and in the Midlands, mainly due to economic reasons. Much of the reason is economic – one cannot make a good business case for electrifying a railway, with the associated cost of overhead wires and their structures, which only has perhaps 4 trains an hour. Regrettably, the automobile manufacturers can justify the expense for a car for about 4 people.

You also have similar problems with non-electrified lines joining electrified ones, but the problem is even worse with passenger trains. The majority of passenger trains are formed of multiple units – that is, trains with engines and traction equipment under the floor, and in fixed formations with a fixed number of carriages. This confers a number of advantages on the train operator, who does not have to spend the time and money of marshalling trains together, or allocate a locomotive of the correct power rating for the train. It makes it almost impossible to make diesel trains run on electricity from overhead wires, however, and bi-modes (trains with diesel engines and electrical equipment) are heavy and expensive.

So again, a solution is demanded to reduce, or preferably eliminate, the emissions of passenger trains, at least the lightly used ones. I am of course not talking of the excellent electric trains, of which you are no doubt aware, that operate in numerous parts of the country. These are already zero emission, at least at the point of use.

At this point, you have either decided that I am waffling far too much, or are curious to know how the railway industry gets itself out of this newly developing pickle. Well, if you are in the first camp, I’m afraid I can’t help you, but enjoy the rest of the internet. If, on the other hand, you find yourself in the second camp, allow me to enlighten you.

One potential solution is to use an alternative fuel – hydrogen. Hydrogen is the most abundant element in the universe, a fact which I’m sure you covered at school, and is also the simplest element, consisting merely of a single proton and an electron. This is all tremendously interesting, but what we are really interested in is that hydrogen can be combined with oxygen in a fuel cell to produce electricity. Electricity which, in sufficient quantities, can be used to power traction motors, and hence a train. Electricity produced with the only waste product being water. Ah, you might say, fascinating, but this all sounds rather sci-fi. The truth is that hydrogen fuel cells are nothing new, and have been used in the space industry for decades, most notably on the Apollo moon missions.

I must admit, readers, before I get carried away, that although hydrogen is the most abundant element in the universe, it can be hard to come by here on Earth. It tends to be combined with other things such as natural gas or water, and the extraction process can be energy intense. The good news is that extracting hydrogen from water (a process called electrolysis) only requires electricity, which can come from renewable sources, or during the night when it is not currently being used.

Hydrogen is not terrifically energy dense, at least in terms of volume, presenting something of a problem to the potential train designer. To get around it, hydrogen is stored in pressurised tanks, fitting much more hydrogen in a smaller space, but even this doesn’t give the energy density of diesel. For a small regional train, this isn’t necessarily a problem. For a freight locomotive… well, we’ll come back to that.

In Germany, a hydrogen fuel cell powered regional train, one of Alstom’s Coradia range, the iLint, is already under test. It will do 140 km/h, which, in British, is 87 mph, plenty on most smaller regional railways around the country, especially considering the increased acceleration that electric motors provide over the conventional hydraulic transmission of a diesel train. Alstom already have their sights set on bringing a version of this train to the UK.

That said, it won’t be as simple as just shipping it over on the next appropriately sized ship. The loading gauge, that is, the width and height trains are allowed to be, is narrower in the UK than on the continent. As such, the train will have to be reworked (a result of the lack of energy density) before it will physically fit on the UK network, which will take time.

Anyhow, support for the idea of hydrogen trains in the UK continues, partly drummed up by a little project from the University of Birmingham. This actually came out of an Institute of Mechanical Engineers challenge, to build a 10 1/4 inch gauge locomotive that can, among other things, recover energy from braking. It was decided to build a locomotive that used a hydrogen fuel cell, mainly, I am told, as batteries would be a rather boring and predictable power source. This locomotive has undergone numerous iterations over the years, but until now was really rather obscure.

Over the past year or so, the locomotive has been worked on, and she has acquired a new set of clothes, a much more pleasing result than in previous years. Officially, she is the University of Birmingham’s IMechE Railway Challenge entry, but she is now better known as Hydrogen Hero. She has already appeared on the local BBC television news, with yours truly at the controls, at Rail Live 2018, even attracting the Secretary of State for Transport, Chris Grayling. On the 30th July this year, she was again demonstrated by yours truly (on the left, in the orange) to Grayling’s opposite number, Shadow Secretary of State for Transport, Andy McDonald:


In doing demonstration runs, our relatively small team has been raising money for Help for Heroes, by taking donations from passengers. I am sure you’ll agree this is a worthy cause, and somewhat justifies the name, but, importantly, this makes our little locomotive the first revenue-earning hydrogen train in the UK.

Now, I may have mentioned earlier the freight side of things, and the trouble with energy density. This is not the only problem. Hydrogen fuel cells produce a fairly constant amount of power, which is fine usually, but during high-power moves, such as starting a heavy train or accelerating up a hill, this is not quite enough. A solution is to charge batteries using the fuel cell’s power when the train is stationary, or cruising using little power, and to use the power stored for the high-power situations. One can also use the motors as generators to charge the batteries when the train brakes, increasing energy efficiency. Needless to say, these batteries also take up space.

A solution to this is to have 2 vehicles, instead of one. In one of these vehicles, you could incorporate hydrogen tanks and batteries, and in the other the power electronics necessary. All the axles of the train could be powered with traction motors, which would also increase the tractive effort of such a locomotive over a conventional one, given that you now have twice . This is the eventual plan with Hydrogen Hero. 

My point, if I may conclude, is that the technology to do this exists today, and that there is no shortage of ideas, particularly in Europe. I firmly believe that hydrogen is the way forward, and I would urge the policy-makers and railway companies to seriously consider making use of the technology.

With that, as usual, I shall wish you an excellent day.







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A blog about nuggets of history, technology and sometimes railways. Peculiar.

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