In recent years, the discovery of small amounts of hydrogen gas underground has spurred a worldwide search for what could prove to be a significant new source of zero-carbon fuel, but so far, prospectors have largely skipped the UK.

According to a on natural hydrogen produced by the Royal Society, that isn’t due to its geology. “There are rocks that certainly would fit within having the potential to produce hydrogen, but the investigations haven’t been done,” says at the University of Toronto in Canada, who led work on the report.

It also isn’t down to lack of interest in the gas. The UK’s latest says that when produced via low-carbon methods, it “has a critical role in helping to achieve our Clean Energy Superpower Mission”, including as a source of power for heavy industry and transportation and in long-duration energy storage. Natural hydrogen, however, isn’t mentioned as a potential source.

Novelty is one reason for this, says at Keele University, UK, who contributed to the report and is an investor in natural hydrogen companies. “Nobody is paying attention, basically. No one is regulating this new subject. No one understands it.”

That could be starting to change. Ball says several companies have purchased rights to explore for hydrogen in parts of the UK, for instance in in the south-west, while relevant research is going on at several universities. The British Geological Survey is also working on a more detailed study of the potential for natural hydrogen in the UK. The country’s rich history of geological study means there is plenty of data to draw on.

And there is reason to think there might be something to find in it. According to the Royal Society report, the UK has ample amounts of the rocks known to generate natural hydrogen, for example iron-rich ultramafic rocks that produce the gas when they react with water. These occur in regions such as the Lizard peninsula in Cornwall and the Shetland Islands in Scotland. Geological formations in other areas such as the North Pennines may also produce hydrogen as a result of natural radioactivity splitting water molecules.

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“It’s most definitely going to be in the UK,” says Ball. “Whether it’s in economic quantities is the question.”

If there is hydrogen to be found beneath the UK, no one should expect “some bonanza of an endlessly renewable commodity”, says Sherwood Lollar. She says one broader purpose of the report was to offer a “course correction” for some of the more dubious claims that have been made about natural hydrogen, such as the idea that large amounts of the gas are rising from deep in Earth’s mantle or even core.

That said, more of how much hydrogen may be generated in the crust are still significant: the report estimates that around 1 million tonnes of the gas seep out of the crust each year globally, which over time could produce some large accumulations. “Even if we can capture a small proportion of this, it could still be an important contributor to the hydrogen economy,” says Sherwood Lollar.

For the first time, electrodes that can make hydrogen from seawater without generating corrosive and toxic chlorine gas will be produced at commercial scales.

“Traditional electrolysis has only been possible with pure water, an increasingly scarce global resource,” at the US Department of Energy’s Advanced Research Projects Agency–Energy (ARPA-E) said in a . “[These electrodes] eliminate the process’s dependence on pure water and it taps into the world’s most abundant water resource instead: the ocean.”

The process uses a negatively-charged cathode and a positively-charged anode to split seawater into four “streams” – useful oxygen and hydrogen, and acidic and alkaline streams that can be easily recycled back into the ocean. Equatic, the California-based startup that designed the technology with support from ARPA-E, plans to sell the hydrogen created in the process to offset their costs. The alkaline stream reacts with CO2 in the atmosphere to form stable minerals that can be poured back into the sea, while the acidic stream can be returned to the ocean once it is restored to a higher pH after flowing over silica-rich rocks.

Like standard techniques that split water to produce hydrogen, this process takes place in an electrolyser, a machine that uses stacks of electrodes to separate water molecules with electricity. But existing devices have trouble working with seawater because it destroys them: it is full of dissolved salt, other minerals, metals and microorganisms that degrade components and gum up the works. Also, the electrical charge that attracts oxygen to the anode separates the salt in seawater, generating toxic chlorine gas that rapidly corrodes the machine.

To avoid this problem, Equatic co-founder Xin Chen and his colleagues designed an anode that can selectively split oxygen from the water molecules without splitting the salt. They used a chlorine-blocking layer to allow water to flow through the catalyst while stopping the salt. Based on laboratory tests, Chen says they expect the anodes will work for at least three years before they need to be removed and recoated.

at the University of Galway in Ireland, who is not involved with the company, says three years would be a strong performance, and these oxygen-selective anodes are a promising approach to using seawater to make hydrogen fuel. But he says they haven’t yet shown they can work in the wild. “What we need to do is see the real performance in a real environment,” he says.

The company will now begin producing anodes at a factory in California capable of making 4000 of them a year. They will be used in a being built in Singapore, which the company says will be able to remove 10 tonnes of CO2 and produce 300 kilograms of hydrogen per day.

The series is an evolution of the current all-electric series, , with the organisers using it to develop hydrogen as a future car technology and showcase its green potential. “We’re using racing to accelerate the adoption, accelerate the innovation around hydrogen,” says Ali Russell, managing director of Extreme E, allowing “you and I to go out and buy our next car as a hydrogen vehicle”.

The Pioneer 25 car uses hydrogen produced using green solar and wind energy sources by Enowa in Saudi Arabia. “In motor racing, we always shoot for gold standards,” says Mark Grain, technical director at Extreme E, who was responsible for developing the car. “We don’t want to compromise and use a lesser form of hydrogen than green hydrogen,” he adds.

However, the racing series is also seen as a technology incubator. While green hydrogen is highly desirable, it is a relatively new technology and scaling to mass adoption may involve less green sources in the interim. “We need to create the right environment for the economics of hydrogen to work, which is about mass adoption,” says Russell. “So whether that’s blue, whether that’s pink, whether that’s grey, whether that’s green,” he says, referring to the various forms of hydrogen production, each of which involves different processes and energy sources, including some that use fossil fuels. “Ultimately, green has got the most important story, but all of those aspects of hydrogen are really important at this moment in time.”

Right now, however, it is all about proving the technology in extreme environments, wrangling performance and getting the car ready to race next season. “We’re not only moving technology, we’re improving the car,” says Russell, “and we’re going to have a much better racing series as a consequence.”  As the car gets put through its paces, it certainly seems to be delivering on that promise. “The Extreme H car is going to be quicker than Extreme E car on track,” says Hedda HosĂĄs, Extreme H’s test driver.