Honda has a vision of a hydrogen future. Not just for its cars, but for how we achieve all our energy needs. Starting with the home.

The company has a vision of a house. With a solar panel roof that provides the power to 'crack' water into hydrogen fuel which can be used to power a fuel cell to generate electricity for the house's power and heat systems.

And which could also be topping up the hydrogen fuel tank of the fuel cell-powered car in the garage.

It all foresees a future of renewable energy, with no CO2 emissions, and of independence from fossil fuels.

Hydrogen Utopia? Well, most parts of it are already here. Including the car in the visionary garage. In this case, the Honda FCX.

I saw it first at the recent Geneva Motor Show. But it already is a sight on streets in California and in Japan. On lease to public authorities for trials.

The future is here. Maybe just a taste of that future. But it runs on real wheels. And represents the best optimism of everyman's personal transport as first given to the world by Henry Ford. Whose successors are also big into the fuel cell future. Ford has its own programme of Focuses powered by hydrogen.

Honda says that 'cars should be the stuff of dreams'. There are a number of ways to dream of the 'hydrogen economy' in automotive transport.

The use of hydrogen as fuel for the century-old-plus internal combustion engine has been achieved in experimental terms by carmakers such as Mazda with a hydrogen version of its Wankel-derived rotary engine, and by BMW with a fleet of its latest 7-Series cars that are touring the world burning hydrogen as fuel.

Honda has gone the more direct route - the pure fuel cell car with the most efficient method of combining the hydrogen idea with electricity.

For those not familiar with the whole idea, a fuel cell uses hydrogen, combined with oxygen, to provide electric power with only water as emissions.

The actual system is fairly simple. The difficulties are mainly concerned with the storage of the hydrogen fuel, which requires a much more strong and pressurised storage tank than does petrol.

In addition, the Honda concept uses a much more complex method of electricity storage than the traditional battery, in this case involving a 'capacitor' system to temporarily store a charge of electricity onboard the car, which has a much better 'instant punch' than can be achieved from a battery storage system. It is used to start the car and to give a boost

Don't feel that 'going electric' will be a downer in fun or performance: the Honda FCX achieves an energy efficiency of 45 per cent, or twice that of the internal combustion engine. And 1.5 times that of of a hybrid car.

The current fuel cell unit is provided by one of the world's leaders in the field, Ballard of Canada, and allows an 'off-the-line' performance comparable to that of a high-powered petrol car. It can do a maximum speed of 150km/h, but more importantly has a range of 355km, twice that of a predecessor car in development just 18 months ago. Honda is also working on a fuel cell unit of its own design.

OK, the car mightn't look much more than Ford Fusion in style and size, but even with the current fairly heavy set of power unit elements, it can carry four people and a reasonable amount of luggage.

And they've done all the crash testing to make sure that even with that big-bang potential of 156 litres of hydrogen on board, it won't.

Let's not be overstating the case. This is an experimental vehicle. It IS operating in real world situations, but I'd hate to be making the repayments on the actual cost of the car itself.

Honda can afford that much better than I can.

Then there's the refuelling, the next big step. Well, major oil companies are looking seriously into that, because they know that their future lies in the adaptation of their petrol distribution system to the hydrogen economy. But Honda, typically, is testing out its own solar-powered 'filling station' at its R&D centre in California.

On the basis that there's no point in 'going green' at one end of the system, the car, if production of hydrogen itself is non-friendly to the environment, this experimental station uses sunlight to convert water into its constituent elements, two-thirds of which is hydrogen.

It wouldn't make a fortune for its operator, but is verifying more efficient production methods for renewable energy.

A door has been opened in a vision ... into a future reality which is already here.