Hydrogen electrolyser wins Earthshot prize

New technology can make clean hydrogen more cheaply and flexibly
29 October 2021




A new technology that can make clean hydrogen from water and renewable electricity has won one of this year’s Earthshot Prize, an important environmental award launched last year by HRH Prince William, whose aim is to find new ideas and technologies to tackle the climate crisis. 

Prince William’s plan is to name five winners every year until 2030, with each winner receiving £1 million in funding. The “Fix our climate” prize is awarded to cities, countries or technologists who remove carbon from the atmosphere to mitigate global heating. This year’s winners were the Thai-German-Italian company Enapter, which developed a technology called AEM Electrolyser, a machine that splits water into its constituent hydrogen and oxygen gases using renewable electricity.

Hydrogen is the most abundant gas in the universe, and is seen as a potential green alternative to fossil fuels because it releases no carbon emissions when burned. Currently, hydrogen is used in fertilisers and oil refining, and the way it is made leads to substantial carbon emissions: ‘grey’ hydrogen is made using methane while ‘black’ hydrogen is made using coal. Some have proposed making hydrogen and capturing and storing the carbon emitted (so called ‘blue’ hydrogen), but the technology to do that at scale has not been developed yet. Instead, in the last few years, researchers and companies worldwide have been looking for ways to make zero-emission, ‘green’ hydrogen.

Electrolysers are the simplest machines to produce ‘green’ hydrogen, but they often use expensive materials and are not very efficient; around 25% of the energy input is lost. Enapter’s new AEM technology relies on an ‘anion exchange membrane’, which is the key component inside the electrolyser that separates the hydrogen and oxygen gases once water is split. Jan-Justus Schmidt, co-founder and managing director of Enapter, says, “The AEM technology combines the advantages of the low-cost alkaline technology with the highly efficient PEM (proton exchange membrane) technology to deliver a product that is both cheap and efficient”.

Moreover, Enapter’s design has the flexibility to be used at different scales according to the requirements. For example, Enapter’s electrolysers have been used to store excess electricity coming from solar panels and to power a small aircraft, but also to provide residential heating in a pilot project in Rozenburg, the Netherlands. “Hydrogen is appropriate for long-term energy storage and it’s a complementary technology to batteries” says Schmidt.

However promising, hydrogen will not be the solution to all our energy problems. In most cases, supplying the electricity directly is a better solution, because it avoids unnecessary energy losses. Prof David Cebon from the University of Cambridge explains that “each time you change energy from one form to another, you lose energy” so using electricity to make hydrogen that is subsequently burnt is less efficient than using electricity directly. “This is not just because the conversion technologies aren’t good enough yet; it’s a thermodynamic limit that we cannot tweak very much” continues Cebon.

Cebon believes that green hydrogen will be most useful for applications in which direct electrification is not a viable option, such as steelmaking, fertiliser production and aviation. Schmidt agrees, saying that “wherever possible, electricity should be supplied directly”, but added that “the nature of renewables is that they are intermittent, so hydrogen will play an important role in our future energy storage requirements”.


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