Toyota proves hydrogen boil-off solution in endurance racing

Toyota is using the demanding Super Taikyu race series as an environment to stress-test and refine its hydrogen technology and has come up with a way of addressing the ‘boil-off’ problem that has been limiting the adoption of liquid hydrogen as an automotive fuel.

Intense endurance racing conditions push Toyota’s hydrogen technology to its limits, revealing weaknesses and accelerating development.

Most hydrogen fuel cell vehicles use gaseous hydrogen, stored in high-pressure tanks, which is fed into a fuel cell that generates electricity to power the vehicle’s motor, or used in an adapted internal combustion engine.

Toyota’s GR Corolla H2 Concept switched from gaseous to liquid hydrogen earlier this year due to the advantages of increased density and extended range, crucial for endurance racing.More importantly, Toyota’s implementation showcases a groundbreaking solution to ‘boil-off’, the vaporisation of liquid hydrogen caused by heat transfer air, which is hard to prevent given hydrogen is only liquid at -253°C or below.

Hydrogen lost through evaporation severely impacts the overall practicality and environmental benefits of liquid hydrogen vehicles and could represent safety issues.

Toyota’s solution lies in a sophisticated self-pressurising system that, unlike traditional methods that require external energy, cleverly uses the boil-off hydrogen gas itself to increase its pressure by a factor of two to four without external energy input. This pressurised gas is then seamlessly integrated back into the fuel system, effectively transforming a previously wasted resource into usable fuel.

Even after boil-off has been used as fuel for the Corolla’s turbocharged three-cylinder engine, Toyota’s system is designed to maximise energy recovery. Any excess hydrogen gas is channelled into a compact fuel cell where it produces electricity equivalent to the amount generated by the alternator, where it powers essential components such as the liquid hydrogen pump.

The final stage of Toyota’s innovative process ensures that any remaining hydrogen gas, after serving its purpose in fuel generation and electricity production, is carefully processed using a catalyst. This process converts the gas into harmless water vapour, which is then safely released into the environment. 

Although currently in the concept phase, Toyota is optimistic about the technology’s potential and is seeking partnerships to refine it for large-scale production.