Are alternative energy vehicles the future? As consumers actively try to do their bit to help clean up the environment - and save on tax, congestion charging and refuelling costs in the process - we're seeing a surge in all-electric and electric-hybrid cars on the roads.

Hydrogen fuel-cell technology is the latest - and cleanest - alternative energy of the lot though. Problem is, it's difficult to service in most countries at present, given the lack of hydrogen fuelling stations.

Honda, however, is a big supporter, with its Clarity Fuel Cell paving the way for more cars of its type on our roads. It's not the only manufacturer investing in the technology either: Toyota, HyundaiBMW and Daimler are also pledging support to the HyFive project - a European project committed to bringing hydrogen fuel-cell powered cars to the mass market, along with the infrastructure to support it.

Although we're not quite at the mass-market stage with hydrogen fuel just yet, we're not talking about science fiction here: we've driven the Clarity Fuel Cell, which joins its biggest rival, the Toyota Mirai, in the green stakes, but ups the ante with a few world firsts.

Can the Clarity be the first car to act as the catalyst for a hydrogen powered future?

Hydrogen fuel-cell technology works by mixing hydrogen gas with natural oxygen to generate electricity, which is then stored in a battery to power a motor and speed you along, with only water residue dripping from the exhaust as a result. It's incredibly clean.

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However, the hydrogen does need to be sourced from somewhere in the first instance. It can be produced using renewable sources, but this method can be quite expensive - which is a major hurdle in making the product mass-market.

The cheapest way to produce hydrogen is to heat natural gases in the presence of steam and a nickel catalyst. The downside to this method is that is produces an awful lot of carbon monoxide and carbon dioxide, both of which are harmful greenhouse gases.

So what's the solution? Kiyoshi Shimzu, project development leader for the Clarity Fuel Cell, says a lot of hydrogen can be obtained as a by-product from steel production to make it can be as environmentally friendly as possible.

The idea of hydrogen as a fuel isn't brand new. Indeed, Honda has been researching and developing the technology since the late 1980s and prior to this Clarity Fuel Cell has already realised seven hydrogen fuel-cell cars (the majority of which were just experimental and not available for purchase or lease, simply made to prove the technology could work).

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So, to Honda's new car: it's the world's first hydrogen fuel-cell powered car to have five seats - the company's previous Clarity could only seat four - thanks to clever positioning and down-sizing of components. This not only increases space inside for passengers, but it improves power output too.

The powertrain in the old Clarity was mounted underneath the driver and passenger sides, but Honda has - in another world first - moved it to the front of the new Clarity, under the bonnet, where you would normally find a combustion engine.

Honda has also reduced the height of the entire unit simply by rotating it 90 degrees. The fuel-cell stack (this is where the hydrogen and oxygen meet) has been on a diet, too, and is now 33 per cent smaller. The number of cells inside the stack has reduced by 30 per cent, too, but the power density of those cells has been increased one and a half times.

The onboard battery sits underneath the driver and passenger. You don't need to plug it in to recharge like you would a conventional electric vehicle, as it's charged by regenerative braking and, of course, the hydrogen fuel-cell.

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Finally, there are two tanks to store hydrogen: a large one that stores 117-litres and a smaller one that stores 24-litres. The two combined can store 5kg worth of hydrogen, which is pumped into the car as a liquid at -40C.

The biggest benefit of hydrogen power over electric power is the range. Hydrogen gas burns at a slower rate compared to the amount of electricity used under the same driving conditions. This means the Honda Clarity has a driving range of up to 400 miles (650km), putting it level with some regular fuel-powered cars on a full tank.

So what's a hydrogen fuel-cell powered car like to drive? If you've driven an electric vehicle before you'll feel right at home as it's just as quiet.

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However, the exterior design will divide opinion as much as it'll turn heads. Is the Clarity the best looking car ever? Absolutely not. It is, however, scientifically designed to be as aerodynamic as possible. There are air vents just in front of the rear wheels which accept air that's been channelled down the side of the car. Which is all well and good from the inside, but we're not sold on the unusual appearance.

Honda has gone to great lengths to acoustically dampen the Clarity to minimise road and wind noise, and to great effect. On our two-hour drive around Copenhagen, Denmark, we only heard a peep of noise from the tyres along with the subtle hum from the motors.

There's also instantaneous response when you put your foot on the accelerator. If you really want to pick up some speed, the Clarity Fuel Cell has a sport mode that increases throttle response. You can see how much power you're generating in the digital driver's display by way of a blue orb. The more power you give, the larger the orb gets.

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Sticking with the eco theme, Honda has clad 80 per cent of the interior with recycled materials, including Ultrasuede accents on the dashboard and Prime Smooth leather on the seats, which has been derived from plants.

You get a whole host of mod-cons, too, including heated seats, rear parking camera, automatic lights and wipers, and a touchscreen infotainment system with satellite navigation. The touchscreen itself wasn't always reliable in operation, and we would've liked a brighter screen implementation to negate bright sunlight. Honda has integrated Apple CarPlay and Android Auto, though, which go some way to making up for the lack of better screen.

Honda has also fitted an air quality sensor in the front of the car which filters the air coming into the cabin from outside through an allergy-free deodorising filter.

While hydrogen powered cars such as the Clarity may be able to drive further than their battery-powered counterparts, refuelling them poses the biggest obstacle. There are currently only eight hydrogen refilling stations in the UK, all of which are in southern England. But the good news is more are coming, and fuel giant Shell has opened up its first hydrogen refuelling station in Hendon.

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Which is a start, but the ball is barely rolling just yet. For us in Europe, this particular Clarity will never go on sale. It will be only be sent to Japan and, for now, California in the US. Honda has said a second-generation Clarity will be on sale around 2022 when, so the plan goes, hydrogen refuelling infrastructure should have caught up.

And what about the cost for a planet-saving spaceship on wheels? In Japan it's available for 7.66-million Yen, which equates to about £43,000. In the US it's only available on a leasing plan, but nominally it's worth $57,000. How about that as a fair price for the future?

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