24h Le Mans
24 HOURS CENTENARY – PERPETUAL INNOVATION ⎮ For over fifty years now, the ACO has endeavoured to make its flagship event more respectful of the environment. Reducing fuel consumption was the first step, but there have been many more initiatives since, with the innovations gathering pace over the last ten years. Carbon offsetting measures have also been introduced with a significant number of trees planted at the circuit and in the surrounding area.
In 1975, the fuel consumption of racing cars had to be addressed: the oil crisis had hit hard in late 1973 and its impact was still being felt. French Prime Minister Pierre Messmer enforced speed limits on the country’s roads to save precious fuel (carbon dioxide was not yet being discussed) and he even attempted to ban motor racing across France. Fortunately, a number of waivers were granted, including for the 24 Hours of Le Mans.
To minimise the race’s impact on petrol imports, the ACO slashed the fuel allowance for cars at the 24 Hours. The calculations meant that only cars consuming a maximum 44 litres per 100 km could win. Jacky Ickx and Derek Bell rose to the challenge and triumphed in their Gulf-Mirage. This was inevitably a somewhat uncompetitive edition, but the end of the crisis was near and there was a return to more liberal regulations in 1976.
Nonetheless, the idea had taken root and when the Group C prototype regulations were introduced in 1982, the ACO began a “race against consumption”, limiting the quantity of fuel allocated to cars to 2,600 litres for the race, permitting a maximum 25 refuelling operations (plus a full tank at the start) and restricting tanks to 100 litres. Porsche fared better than most in the first few years, aided by Bosch which supplied its engine management system. The Porsche 956 driven by Ickx and Bell (sharing the cockpit once again) covered 4,899 km with its 2,600 litres, i.e. a consumption of 53 l/100 km. In 1983, the so-called Group C Junior class – later known as C2 – was created with even more restrictive regulations: just 1,430 litres were available to these cars and their fuel tanks were limited to 55 litres.
Consumption was cut by a further 15% to 2,210 litres for the C1s in 1985. However, the winning Porsche 956 driven by Ludwig, Barilla and Winter still managed to cover 5,088 kilometres while consuming 10 litres less than in 1982, i.e. 43 litres per 100 kilometres. However, the difficulties encountered by the various teams prompted the ACO to reinstate the 1982 allocations to maintain the race’s entertainment value. Nonetheless in 1989, the Sauber Mercedes came close to the record, achieving 49 litres per 100 km.
With the 24 Hours back as part of the FIA Sportscar Championship and its field of 3.5-litre prototypes in 1992, these consumption concerns were rendered obsolete.
From the end of the 1990s, the French government began to champion the virtues and low fuel consumption – and thus low CO2 – of diesel engines. And the public listened because eventually over 70% of new cars sold in France each year were fitted with this kind of engine. However, the 24 Hours only turned to diesel in 2007. Audi then Peugeot raced with V12 TDI engines, battling it out on track for five years.
The regulations opened the race to hybrid cars in 2012. Hybrids combine several forms of energy to power the car, with an electric motor assisting the combustion engine. The electric motor (on the front axle) provided the hybrid propulsion, but the question of how to store the energy generated during braking remained: battery or flywheel? Audi opted for the latter solution for its R18 e-tron quattro. Ultimately, however, the battery was deemed easier to install (for Toyota, Porsche and Audi in LMP1).
In 2012, the ACO also opened the way for innovative cars, and especially those focused on energy efficiency, with its Garage 56 initiative. Nissan seized the opportunity, first with the Nissan DeltaWing, a small car powered by a tiny 4-cylinder 1600 cm3 engine, to demonstrate the virtues of downsizing. Then with the ZEOD RC (for Zero Emission On Demand) in 2014, the first hybrid car capable of completing a full lap of the circuit on electric power alone.
The new technologies being developed by engineers today require much heavier investment, and hydrogen is shaping up to be the solution for the future. However, this system and its environment are being built from scratch.
The engine in a hydrogen-powered car comprises a fuel cell, which is supplied with hydrogen and air. The chemical reaction between the cells that make up the fuel cell stack generate electrical energy, depending on the quantity of the two elements injected. This electricity is then delivered to one or several electric motors that power the car.
The main benefit is that the hydrogen technology only emits water droplets. The car is therefore a genuine zero-emission vehicle. The second but no less important benefit is that refilling with hydrogen at 700 bar (700 times atmospheric pressure) can be done in a similar amount of time as a conventional refuelling operation. This opens the way for long endurance races, or long motorway journeys for the road-going cars that will use the same technology.
The only drawback is that a complete package has to be designed. Firstly, we need to produce hydrogen (the gas is not found in its free form on our planet) through electrolysis using renewable energies (solar, wind or hydro-power), with no carbon emissions (as with gas turbines, for example). Next, we need affordable fuel cells (like all new technologies, their production remains costly for the moment). And although a number of road-going models have already been launched (such as the Toyota Mirai or the Hyundai Nexo), fuel cell technology needs to be developed with the constraints of the racetrack in mind, considering, for example, accelerator response time or resistance to vibrations. Finally, on-board storage has to be studied in-depth (material and shape of the tanks to withstand the necessary pressure) before it can be built into the vehicle chassis. But where there’s a will, there’s a way and the ACO has called on various companies to bring the Mission H24 to fruition.
The Mission H24 prototype is now regularly seen on track, for example just before the 24 Hours of Le Mans, and it took part, outside official classification, in the 2022 European Le Mans Series. With the regulations specifically adapted, it is hoped that the car will compete in the 2024 24 Hours of Le Mans.
In the years to come, hydrogen could see another application. Some companies, such as IFPEN (Institut Français des Pétroles Energie) or Oreca, which Le Mans fans are more than familiar with, are seeking to adapt conventional engines so they can run on hydrogen instead of petrol. Such cars would cost less to produce than those with a fuel cell and their emissions would be extremely low compared to petrol or diesel engines. However, we are only at the dawn of this new technological era… Watch this space in the future!
PHOTOS: LE MANS (SARTHE, FRANCE), CIRCUIT DES 24 HEURES, FROM TOP TO BOTTOM (COPYRIGHT: ACO ARCHIVES): the ACO’s Mission H24 hydrogen-powered prototype in 2021; the Gulf-Mirage driven to victory by Jacky Ickx and Derek Bell in 1975; the Porsche 956 dominated the early years of Group C prototype fuel economy regulations; the Audi R10 TDI, the first diesel prototype to win Le Mans in 2006, with Frank Biela, Emanuele Pirro and Marco Werner at the wheel; Peugeot won the 2009 24 Hours with diesel particle filter technology; in the Audi R18 e-tron quattro in 2012, André Lotterer, Marcel Fässler and Benoît Tréluyer became the first team to win the 24 Hours with hybrid technology; that same year, the Nissan DeltaWing became the first car to occupy Garage 56, reserved for an innovative prototype racing outside official classification; the first version of the Mission H24 prototype alongside its latest iteration (right on the photo above).
