The H24 (pictured above), the successor to the LMPH2G and a contender in this season's Michelin Le Mans Cup, is a competition prototype designed by GreenGT around its electric-hydrogen powertrain and installed in an Adess chassis produced to the specifications of the technology.

New technology, new driving style

The skills required to drive a high-performance electric-hydrogen prototype like MissionH24’s LMPH2G are far removed from those necessary to master a conventional racing car. In fact, they are closer to those required in a racer powered by battery-generated energy like a Formula E, for example. The driver, of course, has to manage his energy consumption as well as its recuperation during the braking phases or when the electric-hydrogen generator unleashes its full power without all of it being used by the car’s four electric engines.

Another particularity is that the electric engines of the LMPH2G do not generate any engine braking when the driver lifts off. This surprised Yannick Dalmas, four-time winner of the 24 Hours of Le Mans, when he tested the car at Spa during the 2018 ELMS weekend “In racing, a car should only have two modes: acceleration or braking.Sometimes, for a few tenths of a second, we keep a little bit of throttle in reserve in what could be called the transition phases, in a series of corners or in a chicane, for example, but it’s almost nothing over the duration of a lap. Sometimes, we don’t mash the brakes as soon as we release the accelerator, in particular when we come into a corner. Everyone, depending on his driving style, plays with this split second when the car’s no longer under load to place it, to stabilize it on its suspension, to take up the line for the corner. But you’re never freewheeling in these moments as, unless you declutch, the gear is still engaged and you have the engine brake; it’s something everybody knows in his ordinary car.But with the LMPH2G, because of the electric engines, there’s no engine brake. If you take your foot off the accelerator without braking, you’re freewheeling and the car no longer has any grip. It begins to float and that can catch you out. But once you’ve got over the initial surprise, you can play with the situation while keeping some throttle in reserve and braking with your left foot as in karting. It’s very pleasant and very efficient too!
In addition to this technique, the driver in the LMPH2G has to manage many more systems than in a conventional car. Norman Nato, (one of the front-running drivers in the WEC with the Rebellion team, two victories in the early part of the 2019-2020 season) who’s the development-performance driver for MissionH24 explains just how electric-hydrogen power gives the driver a central role in achieving performance.

What differentiates the LMPH2G from prototypes with conventional power units is the amount of technical work we have to keep doing on board to manage the generation of electricity by the electric-hydrogen generator and how we use it – immediately in the engines or store it. We can, in fact, store the electricity produced by the electric-hydrogen powertrain or recuperate it in the buffers, little batteries the same size as those fitted to motorbikes that stock temporarily the excess energy produced, but not used so that it’s available when we need it. We programme that during the lap depending on the traffic, our road map, the mechanical state of the car – sometimes you have to preserve its tyres and brakes or try to postpone a refueling stop. In short, there’s a lot of analytical work to do as well as talking to the engineers in the pits.

So the driver plays a central role in achieving the performance of the electric-hydrogen powertrain.

From hybrid to hydrogen

Electric-hydrogen propulsion represents a new phase in the evolution of mobility. After steam, electricity, the internal combustion engine, rechargeable hybrids (or not), the electric-hydrogen cell is the most apt solution to ensure a decarbonized energy transition in transports in the domain of high-power/long-distance mobility. The principle is simple: to drive the car’s electric engines electricity is not stored in heavy batteries integrated into the vehicle; it is generated on board thanks to an electric-hydrogen cell fed exclusively by tanks containing H2. Injected on a membrane the molecule meets oxygen atoms in the ambient air. Immediately, the dihydrogen molecule and the oxygen atom combine in a reaction that has a double effect: heat generation and production of electricity fed to the car’s engines. The intensity of the reaction controlled by the driver using the accelerator generates more or less electricity enabling the engines to produce more or less power. In addition to the heat and electricity the chemical reaction results in the creation of another element from the combination of H2 and O: H2O, pure water which is evacuated in the form of steam. This is all the car rejects into the atmosphere: neither poisonous gasses, smoke nor polluting particules – only water!

For the Automobile Club de l’Ouest, which has given the 24 Hours of Le Mans a role of precursor in the development of mobility technologies for almost a century, the electric-hydrogen solution represents one of the future evolutions of motor sport, especially in the realm of endurance. The club’s association with GreenGT, specialist in high-power electric-hydrogen mobility, was the obvious choice when it came to writing this new chapter in racing – and beyond!

Following section :

The partners