Toyota automotive parts supplier Denso is planning to bring its solid-oxide electrolyser (SOE) to market from 2025, the company confirms to Hydrogen Insight.

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Denso, which is part-owned by auto giant Toyota, announced it would develop an in-house SOE at the beginning of this year and kicked off the first demonstration at its Hirose plant in July.

This demonstration partially displaces grey hydrogen supply, currently used to remove solder oxide and improve the joinability of power cards, a component of inverters used to drive the motors of hybrid or electric vehicles.

Denso’s SOE splits water heated to 700°C into H2 and O2, which the manufacturer says requires less power to produce hydrogen compared to more mature alkaline and proton-exchange membrane technologies which generally react at 60°C.

However, while SOEs are more efficient in terms of electricity input, this requirement for extremely hot water means an external heat source must be present — or otherwise use more electricity to heat the electrolyser.

Many SOE manufacturers therefore recommend using their electrolysers for hydrogen production co-located with exothermic industrial processes, such as ammonia synthesis or power sources that already produce huge amounts of steam, such as certain nuclear reactors.

Additionally, Denso has flagged that SOEs need to maintain this high temperature, as “it is easy for heat to dissipate due to the different in temperature from the surroundings” — requiring extra energy to keep the system hot — while some of the water vapour goes through the system without reaction.

The firm says it has developed a structure to efficiently recover exhaust heat while suppressing heat dissipation from the heat exchanger surface as well as a system to re-circulate steam, based on similar technologies used in vehicle parts.

Additionally, Denso’s design integrates heat insulation with the electrolyser cell in order to keep the whole system compact, rather than assembling these two components separately, which the manufacturer claims is often done for most SOEs.

Updated to include Denso’s confirmation of commercial launch year.