Page 28 - Innovation in energy management: contribution of railways to sustainable mobility

R.12. Boosting traction with hydrogen in a fuel cell

Investment: Nature: Improvement:

Related to:
R.16

The use of hydrogen as an energy vector in new railway traction can help meet
environmental objectives on those lines where electrification is not an economically
viable alternative. Although it is a technology that has been known for several decades,
its commercial application in the railway can still be considered immature or incipient
from a technological point of view, since there is not much experience in its use. We
cannot ignore the fact that large industrial suppliers are betting heavily on this
technology since its use is strongly backed by EU policies and economic aid.

The use of hydrogen has great advantages. On the one hand, the vehicle would be free of
emissions, both in the generation process if obtained through renewable energy sources
(green Hydrogen) and in the combustion process. On the other hand, it enables coverage
of areas greater than 100 kilometres, which is the current limit for recharging batteries.
Another advantage is the reduction of noise emitted by the vehicle, important both for
users and for inhabitants of areas near the railway line.

However, the use of hydrogen has several disadvantages. Amongst them is the lack of
security of supply, understood as the availability of energy resources and the flexibility
of the supply chain to meet the expected demand (both in terms of quantity and quality).
Safety of use can also be regarded as a disadvantage. Safety implies management of the
risks associated with the handling of fuel during transport, refuelling and its use. In this
sense, it is necessary to conduct further technical analysis related to the use of rolling
stock in confined areas such as tunnels and underground stations.

Hydrogen on board the train can be stored as pressurised gas, in liquid form or stored
through other organic liquids. Whilst in the aviation sector, important analysis has been
carried out regarding the use of stored hydrogen (liquid hydrogen is recommended due
to the reduction in the necessary volume and also the reduction in weight compared to
storage in gaseous form), in the railway sector, gases at a pressure of 350 bars are being
chosen, since the treatment of liquid hydrogen requires cryonisation at -257ºC with the
cost and technical difficulties that this entails. It is necessary to continue analysis and find
indicators to increase knowledge and experience in the different options.

The use of other hydrogen-carrying molecules to produce it on board -allowing high
energy densities to feed fuel cells- is showing that bioethanol and renewable ammonia
(liquefied under pressure) can be a great alternative. Both compounds are liquid fuels
and therefore have a high energy density.

It must be acknowledged that the use of hydrogen in rail is strongly supported by the EU
and mandatory in the EU in the coming years in different countries. Most countries in the
European Union have launched their prototype projects, homologation tests or

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Position paper: Innovation in energy management: contribution of railways to sustainable mobility
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