söndag 19 mars 2017

Hydrogen power blind alley?

Alstom's hydrogen powered train, the iLint, based on fuel cell technology, is now undergoing tests. The train is expected to enter service in passenger-carrying trials on the Buxtehude–Bremervörde–Bremerhaven–Cuxhaven (Germany) route at the beginning of 2018. It is zero emission and promoted as a solution for lines which are not likely to be electrified. The exhaust is pure water vapour.

However, whether hydrogen is zero emission or not depends on how the electricity used to make the hydrogen is generated. There are also energy-efficiency questions which need to be considered. There is an immediate loss, the size of which depends on how the electricity used to make the hydrogen is generated. There is a further loss when energy is converted into hydrogen and back again into electricity in the vehicle, and then there are the usual losses associated with the drive train and control systems.

Nor is that the end of the energy losses. There are also losses associated with the transport of the hydrogen, which is not a portable fuel. It has to be compressed and put in tanks. It will liquify only at extremely low temperatures. What is the overall thermal efficiency when all of this is taken into account? There is a discussion of the subject here, in relation to automotive applications of hydrogen fuel cells.

Then there is the platinum issue. Fuel cells require expensive platinum catalysts. Alternatives are not even on the horizon. Platinum mines are not environmentally friendly. Taking one thing with another, this is nothing like as clean as it appears on the surface.

A good benchmark for cost, energy efficiency and performance would be a locomotive-hauled train using refurbished vehicles in push-pull mode. The fuel cell powered train must cost at least £4 million, and probably much more, not to mention the development costs which must be recouped. In comparison, a small steam locomotive such as the DLM design, which has an efficiency around 12%, would cost not more than £2 million per unit, given a minimum production run of twenty. The locomotive, which can run on anything that will burn but realistically can use diesel oil or biomass waste as fuel, easily satisfies current emission regulations. The use of refurbished vehicles gets rid of the bulk of amortisation charges.

As well as being less expensive, such a solution would be far more capable and flexible than a fixed formation passenger unit of any kind.

When running on biowaste, steam locomotives are a zero-net-carbon technology. What a pity that Alstom did not devote its engineering resources to a simpler and less costly technology. Is this a case of not being able to see the wood for the trees?

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