The journey towards fully electric mobility in rail
ANALYSIS – The climate targets set for each country require us to rethink our mobility to make it greener. This has raised a fundamental question concerning the many diesel trains that still run in Europe on non-electrified railway lines. Even if these only represent a minority of the trains per kilometre travelled, the challenge is to stop using the combustion engine in the next few decades.
To go from fossil fuel-based mobility to electric mobility, the first solution is to electrify the railway lines that are not yet electrified. This solution has the advantage of being well mastered for a long time by the rail network managers. But it costs a lot of money and the benefit of the catenary depends on the traffic density. However, there are local lines which we know will never have very high traffic. Therefore, battery powered trains were sought.
Research on this type of train has taken two directions. One is promoting electric batteries with fast recharging at certain points on a non-electrified railway line. The other involves the use of hydrogen, which is a fuel that can be suitable for heavy vehicles, which is the case with trains. In both cases, these technological solutions make trains heavier. This can lead to faster wheel and track wear and make rail service more expensive, at least for the moment, as we can hope that these technologies will progress quickly and will cost less.
Not automatically green
The fuel cell hydrogen train, which is currently attracting a lot of interest, nevertheless raises the question of its production. Approximately 70 million metric tons of hydrogen are already produced globally every year for use in oil refining, ammonia production, steel manufacturing, chemical and fertilizer production, food processing, metallurgy, and more.
The blue and grey hydrogen production is responsible for 830 million metric tons of CO2 emissions each year. This is not negligible. Currently, green hydrogen – the sort needed to reach net zero by 2050 – represents less than 4 percent of all hydrogen produced. Ramping up production is necessary but costly, hampered by a host of technical challenges across the supply chain.
Making the production of hydrogen more sustainable requires the construction of an entire industrial cluster that goes beyond the railway framework. The green production of hydrogen also raises many questions related to the quantity of wind farms, which cannot be extended indefinitely because of urban areas and opposition from residents. There are also the places where the electrolysis takes place, as well as the pipelines that will bring the hydrogen to the refuelling stations, which are often far from wind farms.
Because hydrogen is so much less dense than gasoline, it is difficult to transport. It either needs to be cooled to -253˚C to liquefy it, or it needs to be compressed to 700 times atmospheric pressure so it can be delivered as a compressed gas. All of this has a cost and may take time for planning permission.
Many countries in Europe are currently testing hydrogen trains. It should be considered that a two-mode hydrogen train costs about 30 percent more than an equivalent two-mode diesel train in similar quantities. This extra cost would however be compensated by lower maintenance costs, but what about the wear and tear and weight of these trains? There is not enough experience to make a long-term comparison. It is obvious that the calculation of electrification – or not – by catenary will vary greatly according to the policies pursued and the public finances available. The weight of the hydrogen lobby could play a more favourable role in some countries than in others and wind farms do not have the same density everywhere. By the end, rail policy will also play a role, in terms of whether to maintain small local lines at reasonable cost and what gain it will bring to the community.
Meanwhile, electric trains with rechargeable batteries are also making progress in demonstrating their relevance. There will be choices to be made in the future for one or another technology. It is becoming clear that we are entering an era of technological renewal for regional trains. This is important because the train can then be one of the tools needed to achieve our climate goals. But this cannot be done at just any price.
Frédéric de Kemmeter is signalling technician and railway policy observer.