Alpine Alpenglow: how does its 740bhp hydrogen V6 actually work?

Alpine is preparing to reinvent itself, with its swansong A110 announced (at a quite terrifying price) and set to pave the way for its five-seat replacement… sort of. But the car which has us most excited is its hydrogen-powered rolling prototype, the Alpenglow.

‘Hydrogen’ is the keyword in that sentence, because it’s an idea for propulsion that’s been toyed with for a while now. In the Alpenglow, a hydrogen combustion engine is being used instead of hydrogen fuel cells (as seen in cars like the Toyota Mirai and the Hyundai Nexo). 

The version previewed at this year’s Paris Motor Show is its most potent yet, dubbed the ‘Hy6’. Out goes the original four-pot and in comes a 3.5-litre twin-turbo V6 that spins up to 9,000rpm, puts out 740bhp/568lb ft and maxes out at 205. Crucially, there are three 2.1kg hydrogen tanks for it to dine from, which can store the good stuff at a pressure of up to 700 bars. 

The engine itself took around two years to develop from scratch and is solely intended to be used with hydrogen. But how does it work?

Well, very similarly to a regular combustion engine: fuel and air go into the intake manifold, pistons squeeze this mixture, the spark plugs ignite it, Gandalf the Grey appears and rattles his staff, and you get combustion. Simple, innit? 

But you can’t just throw in hydrogen as a substitute for the fuel/air mixture, because hydrogen ignites differently; essentially popping and banging over a wider range than normal. That means ‘abnormal’ combustions can happen, which is why the combustion chamber needs to be modified to cater. 

Solution? Create a pre-ignition chamber which has a pressure regulator to reduce the hydrogen from 700 to a much friendlier 200 bars, before lowering it even further as it's injected into the chamber. 

But why hasn’t Alpine saved time (and many palavers) by just using fuel cells instead, you may ask? 

Because fuel cells operate at lower temperatures than combustion engines - in some cases, only just warmer than the ambient outside temperature. The smaller the difference between a car’s operational temperature and the ambient temperature, the larger the radiators will need to be. And in a performance car like the Alpenglow, said radiators would be the size of the Mines of Moria.

Switch to a combustion engine and this issue begins to disappear. The operation temperature is much higher than with fuel cells, so the radiators can be more sensibly sized. Particularly since there are things called exhaust pipes to flush out excess waste.

Want to know the other cool thing about hydrogen combustion engines? They’ll be a good option for racing. Racing that’s as noisy and as vibrational as what we’re used to, might we add.

So, Alpine’s new Hy6 engine: yay or nay, folks? Pen your thoughts below.