by Lem Bingley

The hydrogen tanks mounted at the back of Hyundai’s ix35 Fuel Cell car can be pressurised to 700 bar. Which is an almost meaningless number, to me at least. In my world a bar is a unit of chocolate consumption.

So I’ve looked it up. A pressure of 700 bar equates to just under three quarters of a tonne per square centimetre – not the kind of thing you’d want to trap your toe under. Or put another way, 700 bar is roughly the squeeze a submarine must withstand once it’s ventured 4.4 miles under the ocean.



Quite a lot, in other words, and twice the pressure at which hydrogen is currently trucked around by commercial providers. But 700 bar has emerged as the target working pressure for hydrogen-powered cars, as a result of the need to carry a reasonable quantity of fuel in a feasible volume of space.

The ix35 has two tanks, divided to help squeeze them into the available slots at the rear of the car. One, roughly the size of a pub’s beer keg, holds 104 litres and sits under a slightly raised boot floor. The colossal forces inside are held in check by a thick wall of aluminium wrapped in hundreds of layers of plastic. A slimmer equivalent holds another 40 litres, just ahead of the rear axle.



At maximum pressure the pair can embrace just 5.6kg of hydrogen, which Hyundai says provides a range of 369 miles – a distance that will vary according to driving style just as it does with petrol or diesel.

On the move, the ix35’s hydrogen is piped through to a fuel-cell stack sitting under the bonnet. Inside, it does unfathomable things with catalysts and membranes to split the hydrogen molecules up into separate atoms, before recombining them with oxygen from the air to produce water. Electricity and heat – the by-products of the reaction – are what the car can put to use.

From there, the ix35 Fuel Cell works like an electric car, with a 65kW (87bhp) motor driving the front wheels. That doesn’t sound like much power to lug around 1.9 tonnes of SUV, but the motor develops 300Nm of torque – enough to spin the tyres on dry tarmac if too much throttle is used from a standstill. Top speed is capped at 100mph and getting to 62mph takes 12.5 seconds but at urban speeds the ix35 Fuel Cell feels athletically quick. Throttle response is instant and the power delivery uncannily quiet.

A small battery is also included in the powertrain, doing the same duty as the battery in a Toyota Prius. It provides a short-term energy store for capturing braking energy and feeding it back to the motor during acceleration.



As with conventional cars, the efficiency of all the under-bonnet arrangements can vary. Evidently Hyundai is doing reasonably well, given its claimed range. I’m not sure miles per gallon is the right term, but in molecules per mile the ix35 beats the General Motors Hydrogen4 I drove in 2009 by almost a third. A similarly sized off-roader, the Hydrogen4 had a claimed range of 200 miles from 4.2kg of hydrogen (compared with Hyundai’s 369 miles and 5.6kg).

Unlike the Hydrogen4 and most other fuel-cell cars, Hyundai’s car is not a prototype, proof of concept or experimental science project. The company describes it as the first series-production fuel-cell passenger car. “Not hand built,” says Hyundai UK chief Tony Whitehorn, for emphasis.

He says so a bit cheekily, in my estimation, given that a limited run of 1,000 vehicles will be assembled at Hyundai’s factory in Ulsan, South Korea, over a two year period. At that pace, I can’t imagine there won’t be any hand-held spanners involved. However, from 2015, the goal is 10,000 units a year, which does start to sound like a real production-line task. At that point, Hyundai hopes, it might be feasible for the first private customers to order a fuel-cell car. It’s not saying how much they might cost yet, so I can’t say how hard you’ll need to save if you’re feeling keen.



There’s quite a trail to blaze first, assuming the first pioneers hope to fill up with hydrogen rather than use their ix35 FCs as lawn ornaments. About 1,000 filling stations would be needed to provide full coverage across the UK, but the current number is a very long way short of that total. The full count of public-access hydrogen filling stations within the M25 currently stands at one, for example. Sited at Heathrow, it was installed to feed five hydrogen taxis used to impress VIPs during last summer’s Olympic games.

And even that station needs to be upgraded. It pumps out hydrogen at only 350 bar meaning it can only offer the ix35 a half-full tank. Once redeveloped, it will have storage tanks pumped up to 900 bar, allowing it to dispense at 700 bar with ease. Another central London station is planned as part of government-backed efforts to kickstart some sort of hydrogen infrastructure.



According to product manager Robin Hayles, Hyundai’s car will use infra-red signalling to tell the filling station how much hydrogen it needs even before the driver has parked at the pump. Refuelling is designed to take no more than three minutes.

While the price of the car may be a mystery, the hydrogen fuel itself can already be made cost-competitive with diesel, according to Dr Graham Cooley of ITM Power. His company builds hydrogen production apparatus designed to fit inside a shipping container, which he says can pump out hydrogen at £8 per kilogram, including capital outlay, when running at full capacity. The simplicity of the chemistry involved means the container needs only two readily available feeds – water and electricity. If the electricity is zero-carbon, from wind turbines or solar panels for example, so too is the hydrogen fuel.

This kind of setup might make a fleet of hydrogen vehicles feasible for companies, helping to make the case for broader adoption.



The fuel-cell ix35 itself feels good to go. Like battery-powered electric cars, fuel-cell cars require extra vigilance from the driver. The wary eye is not needed for anything untoward happening with the car itself, but to sweep ahead for inattentive pedestrians, who simply won’t hear the car coming.

I’ve seen it before in electric cars, and it happened again with Hyundai’s hydrogen power. People stroll halfway across the road before abruptly clocking the big lump of metal heading silently their way, whereupon they jump out of their skins. Evidently, me hitting the brakes in good time doesn’t do much to lessen the shock.

So I’d recommend that Hyundai invests in some sort of audible alert – preferably the sound of a quietly warbling engine, just as VW plans to add to its upcoming electric Golf. Electronic warning noises might seem more appropriate but in my experience they don’t tend to work.

For the time being, urban ears remain attuned to internal combustion.