Will hydrogen fuel the cars of the future?

A branch of Sainsbury’s in the London suburb of Hendon claimed a UK first last month – a supermarket-based filling station for hydrogen fuel cell vehicles.  This is one of a number being installed across the capital in a project initiated by the London Hydrogen Network and comes five months after the Government’s announcement of £2 million funding for public sector hydrogen vehicles.

However, the jury is still out on hydrogen fuel cell technology for cars.

Cost and efficiency

Before hydrogen can be used as fuel it must be separated from other hydrocarbons.  Refining usually involves adding high-temperature steam to natural gas in the presence of a catalyst (the rare metal platinum, which explains why fuel cells are expensive), producing a reaction which splits the gas into hydrogen and carbon monoxide.  

Oil giant Shell has worked out that the process requires 3kg of natural gas to produce 1kg of hydrogen.  Natural gas counts as a fossil fuel, so its use doesn’t sit well with customers who are in the market for an environmentally sound vehicle.  While hydrogen carmakers can boast that the exhaust pipes emit no pollutants, they cannot claim that the refining process releases similarly harmless vapours.  

An alternative production method is seawater hydrolysis, but this is extremely expensive.  In time, it will be feasible to engineer catalysts to absorb sunlight and use its energy to split water, making the generation of hydrogen greener, more straightforward and less costly.

Critics of hydrogen vehicles point out that they are considerably less efficient and more expensive than electric models.  However, they require less battery capacity, and use a cheaper, less toxic type of battery than hybrid electrics.  The issue of battery capacity is significant because if range is to be boosted, then batteries need to be larger – and larger batteries increase weight, meaning yet more battery power is needed.  This is why small electric cars may be better for city driving, with hydrogen cars coming into their own on long distance journeys: unlike a conventional battery, a fuel cell never loses its charge and will keep producing electricity as long as fuel (in this case hydrogen) is supplied.

Looking to the future

As is always the case with technology, research and engineering developments will eventually overcome the difficulties of producing and extracting hydrogen.  Toyota has already launched a hydrogen car (the Mirai) in Japan and Honda is among the other carmakers working on commercially viable vehicles.

But if hydrogen cars are to take off in the UK, the refuelling infrastructure will need to extend well beyond London.  Toyota and Honda will be pleased to hear that a start has been made, as plans are drawn up for 65 filling stations nationwide.

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