Virtue on two wheels

An ecologically friendly bike doesn't have to be boring, finds Tim Luckhurst

Bovingdon Airfield was once accustomed to dramatic events. During the Second World War, it was the home of General Eisenhower's personal aircraft. The film stars Clark Gable and James Stewart served here, and the First Lady, Eleanor Roosevelt, visited. So did Glenn Miller. Later, it was used to film war movies such as 633 Squadron. Last month, the drama returned, but without a hint of nostalgia.

Bovingdon Airfield was once accustomed to dramatic events. During the Second World War, it was the home of General Eisenhower's personal aircraft. The film stars Clark Gable and James Stewart served here, and the First Lady, Eleanor Roosevelt, visited. So did Glenn Miller. Later, it was used to film war movies such as 633 Squadron. Last month, the drama returned, but without a hint of nostalgia.

The British company Intelligent Energy invited The Independent to road test its revolutionary hydrogen fuel-cell motorbike on the huge runways where bomb-laden B17s had once rumbled. The off-road location was needed because the ENV (Emissions Neutral Vehicle) is a prototype that cannot legally be ridden on the public highway. Only two of these astonishing two-wheelers exist. When I arrived, they were sprinting in parallel along the perimeter road.

It took the ruined control tower in the background to persuade me that I hadn't entered a separate dimension. The ENV resembles one of the speeder bikes ridden by Darth Vader's Imperial scouts in Return of the Jedi. Smooth power delivery makes it appear to be gliding rather than rolling. This impression of gossamer lightness is so realistic that it would not have felt incongruous if the bikes had left the ground and performed aerial acrobatics.

The reason was plain. The human brain associates motorised transport with noise. But even at 50mph, the only audible evidence of the ENVs' presence was a low-intensity hum. Above me, a skylark hung in the air warbling, blithely unconcerned by the thrilling display of ecologically friendly technology taking place below.

Journalists who saw the ENV at its launch at the Design Museum but did not ride it considered it to be more like a mountain bike than a motorcycle. That impression does not survive a spell in the saddle. The bike's hollow-cast, aircraft-grade aluminium frame means that the ENV is as light as a pedal-powered bicycle, but its performance is incomparably better.

This machine will not be pushed into the gutter by inconsiderate car drivers. It nips up to 50mph with effortless grace. The low-revolution torque associated with electric motors gives impressive acceleration from a standing start. The ENV reaches 30mph in just over seven seconds and 50mph five seconds later.

These basic statistics point to the revolutionary truth: Intelligent Energy and its design partners, Seymourpowell, have created a completely functional hydrogen-powered motorcycle. It easy to imagine thousands of these whirring around London, Beijing or Jakarta. The prototype is good enough to ride to work today. This is Tomorrow's World, pie-in-the-sky technology only in the sense that it will take political investment to make it spread. It works well now.

A team that lacked confidence in its technology would not permit a prototype to be subjected to the type of use I gave it. But the ENV does not need cosseting. It responds instantly to a twist of the throttle, manoeuvres with feline agility and is robust enough for off-road use. I would feel equally confident riding it through the heart of a congested city or along a rutted track. It is a clean vehicle for polluted cities and developing economies alike, but, crucially, it does not ask the rider to accept compromise.

The 50mph top speed of the prototype models was chosen to demonstrate a scooter-style bike, but the technology can produce a 100mph version. The hydrogen fuel cell permits cleanliness without subduing performance. It works by converting hydrogen and oxygen into water and electricity. The only emission from the ENV bike is a gentle flow of water vapour from twin cathode exhausts. The first users of hydrogen fuel cell technology, the Apollo astronauts of the 1960s, used to drink it - it is really that clean.

The bike is actually driven by a 6Kw electric motor. The essential difference between this and that road-going joke the Sinclair C5 is the source of electricity. The fuel cell powers the ENV bike for four hours on a single fill of hydrogen. That permits a minimum range of 100 miles, but a clever rider can go further.

Every time you close the throttle the bike switches from using power to generating it. A display in the top of the fuel cell tells the rider whether he is discharging or recharging. By accelerating and coasting in pulses, it is possible to conserve a lot of energy. This, of course, is exactly how we are obliged to ride in urban traffic.

Filling with hydrogen to convert into electricity takes five minutes. I watched Intelligent Energy's research director, Damian Davies, refill the fuel-cell he designed. It was simple. The cell, or core, lifts out of the fuel tank-shaped pod between handlebars and saddle.

Seymourpowell designed the ENV bike to prove that Intelligent Energy's hydrogen fuel cell is ready for application to real vehicles. The result offers tangible evidence of what personal transport could be like in a cleaner world. The prototypes are light, fast and utterly practical. They also look fantastic. If that sounds utopian it is because clean power on a stylish vehicle robust enough to go anywhere is exciting. Frightened petrolheads can relax: it is possible to go fast without burning carbon.

Given the political will, millions of us will soon use fuel-cell vehicles and some of us will even race them. When that happens, the pits will be strangely silent, but that lark above Bovingdon airfield will not be the only one singing.