Press Release

High expectations for hydrogen fuel cells

Hydrogen is very attractive as an alternative to fossil fuels, as it can be combined with oxygen in a fuel cell to produce electrical energy, heat and water. Unlike burning fossil fuels, there is no carbon dioxide, carbon monoxide, oxides of nitrogen or sulphur, or particulates.

If the hydrogen is electrolysed from water using electricity that has been generated using a �eclean�f source – such as wind, wave, tidal or solar energy – then it is very environmentally-friendly.
The fuel cell concept has existed since the mid-nineteenth century but it was only in the second half of the twentieth century that fuel cell research led to units being produced commercially, albeit in small numbers. Now, with record oil prices and concerns over global warming, fuel cell development has reached a point where there are units available for a variety of applications, from automobiles to lighthouses (see panel).

Given the prevalence of automobiles, their combined fuel consumption and their contribution to global warming, it is only to be expected that a substantial amount of research is being undertaken into hydrogen fuel cells for automotive applications. Honda was the first carmaker to put a fuel cell car on the road with regular customers, delivering the Honda FCX to fleet users in the USA and Japan in 2002. The company has now unveiled a fuel cell vehicle that delivers superior environmental performance and is said to be fun to drive, known as the FCX Clarity, which is due to be available in the summer of 2008. Startup and acceleration times are claimed to be comparable to those of a similarly sized car with a 2.4-litre internal combustion engine.

Honda's engineers set out to design a car with components optimised to give an enjoyable driving experience. One result of this was the V Flow Honda FC Stack, which is a lightweight, compact, high-output fuel cell stack. Compared to the 2005 FCX stack design, the V Flow FC Stack features an entirely new cell structure that achieves a higher output of 100 kW, smaller size and lower weight, with a 50 per cent improvement in output per unit volume volume, and a 67 per cent increase in output per unit mass. Because the new stack uses a vertical flow of hydrogen and oxygen instead of the more conventional horizontal flow, water drains away more easily, power generation is more stable and the stack's size and weight are reduced. Another feature of the stack is wave-shaped flow channels that improve hydrogen and air diffusion, thereby helping to improve the electricity generation performance.

To complement the hydrogen fuel cell stack and provide additional power for acceleration, the FCX Clarity has a compact, high-efficiency lithium ion battery to store electricity from regenerative braking.

The engineers also made the fuel cell system, drive motor, hydrogen storage and other powertrain components more compact, and took advantage of the fuel cell vehicle's layout possibilities to create a revolutionary new platform with a low centre of gravity for sporty, stable driving performance. The fuel cell stack is housed in the central tunnel, the battery is under the rear seat and the hydrogen fuel tank is located between the rear wheels.