The latest demonstrator car that could help pave the way for hydrogen-fuelled machinery at the 24 Hours of Le Mans will now store the element in liquid form rather than gas.
Mission H24, a project backed by Le Mans organiser the ACO, has been exploring hydrogen fuel as a low-emission solution for endurance racecars since 2018.
The H24EVO is the third car to be built under the initiative; its technical details were first announced without a car name in October 2023 and the vehicle design was publicly unveiled at Le Mans last year.
The initial plan for the LMP3-based H24EVO was for it to run on hydrogen stored in gas form, like its predecessors the LMPH2G and the H24. It was to have two storage tanks with a combined capacity of 7.8kg.
The gas was to be injected into a fuel cell stack, where an electrochemical reaction would generate electrical energy that the single, rear-mounted motor could use to power the wheels.
Now, the hydrogen will be stored as a liquid, with the car’s developers targeting 11-14kg of fuel on board.
This, they estimate, would enable the H24EVO to run for 40 minutes: more than the half-hour duration projected when the concept was launched over a year ago.
One major reason for switching from gas to liquid storage is that the latter has a greater power density, meaning increased power from the same size of fuel cell.
The liquid density of 71kg/m3 at 1bar is close to atmospheric pressure, whereas hydrogen gas is compressed to 40kg/m3 at 700bar.
However, a challenge of storing the hydrogen as a liquid is that must be kept at extremely low temperatures, around 254degC, compared with 20degC for gas. The liquid also needs to be evaporated to be used as a gas in the fuel cell.
The cell is set to generate electrical energy in the way that was first announced. It will contribute some of the generated energy to the motor, but a 400kW, 3.4kWh battery will help the car reach its stated 650kW (870bhp) maximum output through regenerative braking.
Mission H24 is targeting a track debut for the H24EVO in the first half of 2026, which is a year later than originally planned.
The car’s functions will be controlled through a McLaren Applied VCU and it will run on Michelin tyres that will soon be adopted by the FIA World Endurance Championship and IMSA Sportscar Championship’s top classes.
‘We’re facing a pioneering and sustainable challenge to create zero-emission automobile racing and the mobility of the future, with the deployment of the hydrogen solution,’ says Bassel Aslan, Mission H24 technical director.
‘After demonstrating the potential of gaseous hydrogen, we’re embarking on a new challenge: introducing liquid hydrogen into racing.
‘With an experienced partner in the field of on-board liquid hydrogen storage, and with all our partners, we are starting an exciting and promising collaboration.’
The supplier for the liquid hydrogen storage tank is to be confirmed. OPmobility, formerly Plastic Omnium, was down to supply the gas tanks but was not listed as one of the project’s partners in a recent press document about the updated car.
The ACO is set to welcome different types of hydrogen technology to Le Mans, including fuel cell cars and vehicles that run on hydrogen-fuelled internal combustion engines.
‘After introducing gaseous hydrogen to the racetrack, MissionH24, with the H24EVO, is now embarking on a crucial new phase with a dual challenge: to engage liquid hydrogen in competition and to rival the competition from conventional combustion engines,’ says ACO president Pierre Fillon.
‘This mission is essential to achieve zero CO2 emission in motor racing.’
- Daniel Lloyd
