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Demonstrating the power of hydrogen

01 Jan 2008

A pan-European consortium aims to demonstrate a hydrogen fuel cell powered passenger train in Denmark during 2010

Claus Torbensen,
International Project Manager, Hydrogen Innovation & Research Centre

IMAGINE a train which is nearly silent, whose only exhaust is pure water. A train without overhead wires, running on fuel produced using renewable energy. But this is no futuristic dream - the VLTJ Hydrogen Train Project aims to launch Europe's first hydrogen fuel cell train in 2010.

The consortium behind the project currently includes Vossloh, the University of Salerno, Strandmøllen Industrigas, Dana Tank, Denmark's Hydrogen Innovation & Research Centre, the UK's Rail Safety & Standards Board, and Danish independent railway VLTJ.

We believe that hydrogen can become a commercially feasible alternative to diesel or electric traction within the next 15 to 20 years, if train manufacturers and operators want it to happen. They must join forces to obtain funding from the European Union, and elsewhere, and support a systematic development programme which will be an important step towards a sustainable future for the rail industry.

Our plan is to initiate a joint European development project, and launch a prototype two-car multiple-unit into service on the Vemb Lemvig Thyborøn Railway during 2010.

This 60 km independent railway in the northwestern corner of Jylland provides an ideal testing ground, as VLTJ manages all operations and possesses its own fully-equipped workshop and train servicing facilities. The single-track line is generally flat, and the low-density service demands only only moderate power from the fleet of five single-unit Y-train railcars.

We will be able to test an entire fuel cell-based propulsion system under real-life conditions, on a scale that is big enough to be useful and viable but small enough to be economical.

Energy choice

The level of traffic is a key factor when comparing the cost of electrifying an existing railway with the cost of alternatives.

One can calculate or estimate the number of vehicle-km per kilometre of electrified track. Along with the electrification costs per track-km this number can be used to calculate the average costs per vehicle-km. This resulting number should be the critical factor in deciding between conventional electrification and the adoption of alternative traction.

Converting a railway for hydrogen trains will not require major investment in infrastructure, only in new rolling stock and the fuel supply. At present a hydrogen train would be considerably more expensive than its diesel powered equivalent, but this is certain to change over the next 10 to 15 years.

A recent study undertaken by the UK's Rail Safety & Standards Board estimated that if the general cost targets for fuel cell technology are reached by 2020, a hydrogen train would be only 5% to 15% more expensive than an ordinary DMU, and hydrogen power will be more cost effective than electrification on railways with low to medium traffic densities.

But the application of general cost estimates to specific applications such as trains is not entirely without problems.

Energy efficiency

With diesel traction, only around a third of the energy in the fuel is converted to kinetic energy. With electric traction, almost 90% of the energy from the grid can be transferred to the wheels. Of course the losses in the power station and during transmission need to be added, and when the electricity is produced by fossil fuels the overall efficiency 'from well to wheel' is not quite so impressive. But if the electricity comes from renewable sources the overall efficiency remains high.

Hydrogen fuel cells have a lower energy efficiency then conventional electrification, due to the conversion losses in hydrogen production (electrolysis has an 80% efficiency), hydrogen storage (90%), the fuel cell (45%) and electric motor (90%). But hydrogen fuel produced using renewable energy will still have an overall energy efficiency comparable to diesel traction at roughly 30%, and that is before we take into account the considerable gains that can be achieved through the use of regenerative braking.

Hydrogen for railway use can be produced by electrolysis of water, with the environmental benefits dependent on the method of electricity generation, which can include renewable sources such as wind turbines. Surplus industrial hydrogen is a shorter-term source of fuel, and both options are currently available at the project site.

Timescale for hydrogen trains

It has generally been assumed that hydrogen technology for railways will develop as a spin-off from any future commercial use for road transport. The mass production of fuel cells and other components for the growing car and bus market would lead to a dramatic reduction in unit cost, enabling the technology to be transferred and modified for rail use at an affordable price.

But even if the general development of hydrogen and fuel cell technology does bring lower prices, longer cell lifetimes, and better and cheaper methods of hydrogen production and storage, there will still be areas of development which are specific to the rail sector. Therefore, the technology needs to be tested, adapted and demonstrated on a train.

The most important rail-specific requirement is the need for a longer fuel cell lifetime. Fuel cell lives suitable for rail applications will not be developed as a spin-off from automotive projects, as car cells will not require life times of more than approximately 5 000 h. RSSB found that the average engine lifetime before overhaul or re-engining is up to 18 000 h for DMUs and 30 000 to 40 000 h for locomotives, with vehicle lifetimes of 120 000 h.

Other specific areas which need investigation and demonstrating include the impacts of the mechanical parts, the safety issues surrounding hydrogen, which mainly concern storage, and last but not least the development of control systems and battery/fuel cell combinations optimised for train drive cycles.

Hybrid drive systems will be needed to obtain the maximum benefit from fuel cells, which give the most efficient performance and a significantly increased lifespan if they run with a stable load. In service the fuel cell will charge a large battery when not required to power the train, with the train drawing on the battery for additional power at times of high demand such as when accelerating from a station. The battery will also store energy produced from regenerative braking, providing further efficiency improvements. This combination of battery and fuel cell will enable a reduction in the size of the cell, which is currently the most expensive component of a hydrogen system.

Act now

Developing fuel cells with a sufficient lifespan for a train, optimising performance and getting the costs down to a realistic level could easily take 10 years. Even a moderately ambitious timetable which would see the introduction of hydrogen technology on rails in 2015-20 requires a systematic development programme to begin now, and encompass different train types, applications and test sites.

A joint European development and demonstration programme during the next 10 years must be one of the spearheads in this development, but immediate action is required. Demonstration projects in North America (RG 8.05 p494) and Japan (RG 7.07 p423) are already initiated or well under way, and if European train manufacturers are to have a share of this potentially lucrative market, they must initiate development and demonstration activities now.

VLTJ Hydrogen Train Project members

Dana Tank Denmark on-train storage
Hydrogen Innovation & Research Centre Denmark project development
RSSB UK safety assessments
Strandmøllen Industrigas Denmark fuelling infrastructure and hydrogen supply
University of Salerno Italy control systems and hybridisation
VLTJ Railway Denmark test facilities
Vossloh Germany train production and systems integration

For more information on the hydrogen train project visit www.hydrogentrain.eu

Rail Safety & Standards Board report T531 Feasibility study into the use of hydrogen fuel is available at www.rssb.co.uk

  • CAPTION: The 60 km Vemb Lemvig Thyborøn Railway provides an ideal testing ground, with a self-contained route which makes only moderate power demands from the current fleet of Y-train diesel railcars. Hydrogen is available locally, and the high proportion of visitors using the line will help raise the international profile of the project
  • CAPTION: More than 800 turbines on the North Sea coast of Ringkjøbing provide a total generating capacity of nearly 400 MW. During windy periods the energy is sold cheaply on the spot market, but each of the eight 2 MW turbines alongside the railway could generate power to produce hydrogen for five trainsets