London Mayor Ken Livingstone has placed a £10m order for 10 hydrogen-fuelled red buses to run on the capital's streets.
The buses will use the hydrogen to generate electricity, and storage batteries and electric motors will replace a mechanical transmission to achieve maximum fuel efficiency. Five of the vehicles will burn hydrogen in ordinary Ford combustion engines which will power electric generators; the other five will use fuel cells to produce electricity directly.
The buses will be manufactured by US company ISE Corp, which offers a wide range of hybrid and hydrogen-fuelled heavy vehicles. According to the company spec sheets for its Hydrogen Hybrid Internal Combustion Engine and Fuel Cell Bus technologies, the two approaches are broadly comparable in performance.
The fuel cell buses use their hydrogen more efficiently, achieving more range for less gas - on the other hand the combustion-engine ones deliver higher peak power for less weight and are apparently a good bit cheaper. Neither of the ISE designs uses cryogenic liquid hydrogen, instead storing the explosive gas in high-pressure roof tanks.
The London buses will cost an average of £1m each, nearly eight times the cost of a normal diesel bus, but London transport bosses reckon it's a sensible investment. They say the public sector needs to drive cleaner transport technology forward.
"London is now the first city in Europe to commit to a hydrogen bus fleet of this size, which will match traditional diesel buses in terms of performance," Mayor Ken Livingstone told Reuters.
"This represents a huge step forward from the previous hydrogen trials in the capital and is an important step towards my target of having five per cent of all public sector fleet vehicles powered by hydrogen by 2015," he added.
Hydrogen vehicles have almost zero emissions compared to ordinary diesel jobs, though the combustion ones do give off small amounts of nitrous oxide. However, at present commercial hydrogen is made by steam reforming of natural gas, a process which involves heavy atmospheric carbon emissions.
In future, hydrogen could be made using electricity to split water, a process which would be as clean as a whistle. This would be expensive at current electricity prices, however, and of course the generation of electricity today typically involves pollution and carbon emissions.
For a truly carbon-free future, one would need an all-hydrogen or electric transport fleet, which would involve a seriously increased demand for electricity. That much larger amount of electricity would have to be generated affordably and cleanly, too, which would probably involve some difficult decisions.
For now, Mayor Ken only wants five per cent hydrogen power. He is also well known for his cheap-oil deal with increasingly-totalitarian Venezuelan strongman socialist Hugo Chavez, under which the other 95 per cent of the London bus fleet gets cheap fuel. Is Red Ken starting to turn into Green Ken? ®