Fuel cells have been around for decades, and the science behind them isn’t complicated. Essentially, they use oxygen from the air and combine it with hydrogen to create electricity, sufficient to power a motor. A car using a fuel cell as its only power source emits heat and water – nothing more – and so qualifies as a zero emissions vehicle. Fuel cells saw service in the Apollo craft used for the moon landings but the first wheeled vehicle using them was a modified farm tractor, built in 1959.
General Motors pioneered their use in passenger vehicles, harnessing the technology in 1966. Called the Electrovan, GM’s van-based vehicle could run 120 miles between fill-ups of compressed hydrogen and reach 70mph, too. But, although it was the size and shape of a modern Ford Transit, the space needed for the hydrogen tank and stack of fuel cells left room for only the driver and a single passenger; plus no luggage.
Other car makers have since pitched in, refining the process and reducing the size of the fuel tank by designing them to accept hydrogen at very high pressures – 10,000psi or more. The size and cost of fuel cells has also reduced over time.
Honda has trialled its fuel-cell version of its FCX small hatch (a US-only model) and has leased dozens to volunteer early adopters in California, most of whom have given glowing reports.
Mercedes-Benz, too, has produced a fuel cell bus, and as many as a dozen other manufacturers have also got themselves involved. At time of writing, a number are promising to launch fuel-cell cars by as early as next year. Toyota (April next year for around £40K) and Mercedes are prominent among them.
Don’t go thinking, though, that within a few years, fuel cell technology will outstrip that of electric cars to pose a head-on challenge to the internal combustion engine.
Nowhere to fill-up
Key to the development of fuel cell cars is the availability of a fill-up network for hydrogen. Because of the high pressures we’ve already mentioned at which hydrogen must be compressed in car tanks, filling up is more involved. What’s more, at present there is no network of pumps – the US has just 10 publicly available fill-up points.
And if even such problems are overcome, the crunch comes with the environmental questions surrounding this propulsion method. The hydrogen ‘fuel’ has to be produced, which (without going too far into the nitty-gritty of how) is a pretty energy-intensive business. Most hydrogen is made by a process known as ‘steam reformation’, which some critics say ‘loses ’a fair percentage of energy along the way. Then there’s the question of the vehicle’s efficiency.
The science behind a fuel cell is rudimentary: it’s made up of just three main elements – an electrolyte, an anode and a cathode. These react to generate electricity, when then powers a motor. In some ways, a fuel cell is little different to a battery.
Cost more, do less?
However, while experts rate fuel cells as more energy-efficient than diesel or petrol engines, they are much less so than a standard battery, charged using mains electricity and turning a motor. And there’s a feeling in some camps that there’s little sense in putting time and skill into developing the technology for cars when using a battery and a motor is more efficient and far closer, too, to wider acceptance?
Another issue is the cost of the vehicles. The high pressures in the fuel tank and also in the reaction process mean that vehicles must be built strongly and to very fine manufacturing tolerances. There’s also the vexed question of safety when a crash occurs and so risks the release of a gas stored under extreme pressure. Doubtless production cars will meet current safety standards – but at considerable extra cost.
While fuel cell technology remains of interest to vehicle manufacturers we don’t see it as an alternative to electric cars unless it unexpectedly leaps ahead in its development. As things stand, electric cars have the upper hand.