The idea of a hydrogen-powered car racing at the 24 Hours of Le Mans is one step closer to reality with the Automobile Club de l’Ouest revealing its latest prototype concept for 2025.

The ACO and GreenGT’s Mission H24 project first bore fruit in 2018 with the launch of the LMP2HG prototype, which turned demonstration laps and utilised hydrogen refuelling technology. It also appeared in two rounds of the Le Mans Cup series, sharing the track with LMP2s, LMP3s and GT3s but racing alone in the Innovative class.

Lessons from the LMP2HG fed into the H24, also based on an ADESS LMP3 chassis, which was introduced in 2021 and sported upgraded transmission and braking systems among other updates. The H24 also ran in the Le Mans Cup but always at the rear of the pack.

However, the third-generation Mission H24 concept, the name of which is open to public suggestion, is designed to push the boundaries of hydrogen powertrain performance with the goal of matching GT3 machinery that will start racing at Le Mans next year.

Power comes from electrochemical reactions in the stack of Symbio hydrogen cells that convert the fuel’s chemical energy into electricity, as well as heat and water by-products.

Hydrogen fuel cell firm Symbio started out in Grenoble in 2010 and is now part-owned by Stellantis. It has 750 staff (ACO)

The car will have two Plastic Omnium fuel tanks each capable of storing 3.9kg of hydrogen at 700bars of pressure for a total weight of approximately 100kg. The intention is for this to last around 25 to 30 minutes in racing conditions, compared with the 40- and 50-minute stints that LMP2s and Hypercars typically do at Le Mans.

TotalEnergies is working with the ACO to develop the hydrogen refuelling infrastructure required for Le Mans. Under the Mission H24 project, the French company developed the world’s first mobile hydrogen refuelling station to be used at racetracks.

Power delivery at the rear wheels has been refined from two electric motors to a single electric motor, shedding 18kg since the H24. The future prototype will have a maximum output of 650 kW, higher than today’s Hypercars, while the motor will have a power density of 20 kW/kg.

Widening the operating range of the motor enables a single unit to be used. A 400kW lithium battery, 12kg lighter than the H24’s equivalent, will recover the car’s braking energy and provide some power to the motor.

German constructor ADESS will continue to provide the chassis for the third-generation hydrogen prototype. The cockpit will be centrally positioned with the cell stack, fuel tanks and motor all situated behind the driver. Render images show the windscreen extending far along the front of the car, with cooling vents on either side.

The design of the third-gen hydrogen prototype marks a return to the sleekness of the LMP2HG but with new features (ACO)

A maximum weight of 1300kg is targeted, removing 150kg from the weight of the H24. Hypercars are not allowed to be under 1030kg but their final weight is usually higher depending on Balance of Performance.

The general design of the hydrogen prototype is expected to be finalised by March, potentially enabling a mock-up to be ready for presentation at next year’s 24 Hours of Le Mans.

All-important power unit bench testing is then projected to begin from October 2024, followed by the car assembly and maiden shakedown in early 2025.

‘Thanks to MissionH24, hydrogen technology has stood out in the competition world,’ said project technical director Bassel Aslan.

‘Now the time has come to prove that this technology can offer an alternative to fossil fuels with the same efficiency and zero CO2 emission.

‘This new car will be for those involved the real symbol of the future of motorsport in line with the energy transition.’

The H24 did last year’s Le Mans support races to showcase the event’s future. Its best qualifying lap was a 4:12.432 (JEP)

Mission H24’s third-generation car will continue the trend of testing hydrogen fuel cell technology, although the ACO has opened its future hydrogen racing class up to vehicles powered by hydrogen-fuelled internal combustion engines.

The ACO, which organises Le Mans and the FIA World Endurance Championship, is one of the key players in the adoption of hydrogen technology in motorsport. Its aim of introducing a new class in the coming years gained momentum when Toyota revealed a hydrogen fuel cell prototype concept at this year’s 100th anniversary Le Mans edition.

However, the ACO could be pipped to the post in terms of introducing a competitive hydrogen racing class if the FIA Extreme H Championship makes an on-time 2025 debut.

‘After introducing hydrogen to the racetrack, MissionH24 is now entering a new phase: bringing hydrogen to competitive racing,’ said ACO President Pierre Fillon.

‘This new prototype clearly intends to rival the other forms of energy in the field. Hydrogen technology is safe, reliable and can perform.

‘The ambition is now to provide the first zero-emission winner of the 24 Hours of Le Mans.’

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