The gold hydrogen rush: Does Earth contain near-limitless clean fuel?
by James Dinneen  /  31 January 2024

“As we drive out of Muscat, the white buildings of Oman’s capital give way to an expanse of open sand ahead of the foreboding Hajar mountains. It takes us 2 hours to reach our destination, a journey that includes our SUV nearly getting stuck in the narrow back alleys of a town. But, eventually, geophysicist Ammar Alali and I arrive at a peaceful spring in the desert, surrounded by golden grasses and date palms. Alali frowns disapprovingly at a stream of bubbles in a pool of water. “It’s energy going to waste,” he says. I have come here because Oman’s mountains are at the forefront of a global search for a new and potentially transformative fuel, sometimes called “gold hydrogen”. Colourless and odourless, this gas has good environmental credentials because it burns cleanly, producing nothing but water. Usually, however, we have to make it in an emissions-intensive process.

But here in the mountains of Oman – and in places with similar geology across the world – it is naturally generated underground, potentially in vast quantities. Proponents of using this form of hydrogen say it could dramatically accelerate our transition to net zero, which explains why researchers and start-ups are prospecting for it far and wide. Many questions remain, though, not least how much of it there really is and whether it can be easily tapped. For his part, Alali, co-founder of geological resources firm Eden GeoPower, wants to test something even more ambitious: can we stimulate the ground to boost the amount of hydrogen it produces?

Dreams of a hydrogen-powered economy have been around for decades. It would mean a world in which trucks, ships, planes and heavy industry run on the clean-burning gas instead of dirty fossil fuels. The trouble is, we currently have to make the hydrogen ourselves, which requires energy and produces pollution. Today, almost all of the 100 million tonnes the world uses annually is supplied by reacting natural gas with steam, a process that releases massive amounts of carbon dioxide. There are cleaner ways of making hydrogen (see “The hydrogen rainbow” below), including “green hydrogen”, which is made from water using renewable energy, but these methods are currently minor players in the industry.

How much natural hydrogen does Earth hold?
In all cases, synthetic hydrogen is best seen as an alternative way of storing energy. A natural supply might instead be a genuine source of energy. Yet despite hydrogen being the most abundant element in the universe, most researchers thought Earth’s stocks of it in its gaseous form were scarce. Drillers in search of fossil fuels sometimes found it in their wells and ocean explorers saw it trickling from sea-floor vents. But no one was actively looking for hydrogen and these discoveries were considered exceptions; hydrogen was thought too reactive to accumulate in large amounts.

“Malian company preparing to extract hydrogen from
underground deposits near village of Bourakébougou”

That assumption was challenged in 2012, when a water well close to the town of Bourakébougou in Mali was found to contain a large reserve of hydrogen. This gas occurred naturally, meaning the only energy input required in its production is that needed to collect it. This kind of hydrogen goes by several names – white hydrogen and natural hydrogen, as well as gold hydrogen – but it is most usefully called geologic hydrogen. Since that find, a flurry of prospecting has led to the discovery of what may be significant underground reservoirs in France, Spain and Australia. We have also found hints of such hydrogen across swathes of the globe (see map, below).

A handful of companies are drilling exploratory wells in the US, including a tight-lipped start-up called Koloma, backed by nearly $100 million from Bill Gates’s venture capital firm. “There are a lot of people searching around the planet,” says Eric Gaucher, an independent consultant in France who left a large oil and gas firm to pursue natural hydrogen. “One of them will find something that is very big and economic. I am convinced.” In the past decade or so, excitement over geologic hydrogen was largely confined to a few true believers in industry.

Then, in 2022, researchers at the US Geological Survey revised their estimates of how much such gas there could be in the ground based on the little that was understood about how it is formed. Their modelling suggested there could be trillions of tonnes available, far more than anyone had previously suspected. If just a fraction of that could be recovered, it would be enough to meet our projected hydrogen demand for centuries. These results generated widespread media coverage. “It’s gone from a fringe novelty to squarely getting everyone’s attention,” says Avon McIntyre at HyTerra, an Australian company focused on geologic hydrogen.

The interest may be justified. Gaucher says meeting even 20 or 30 per cent of our growing hydrogen needs with such sources would free up huge amounts of clean energy that would otherwise be used to make green hydrogen. It may even be a renewable resource if it is continually generated below the surface. But, on the other hand, there are reasons to be cautious about what has been called “gold hydrogen fever”. The true amount of hydrogen the planet contains, as well as how much might be feasible to extract, remains uncertain. It is also unclear precisely how geologic hydrogen is made.

Researchers think at least some is gradually seeping into the crust from the mantle below, where it built up during Earth’s formation. Some may be generated by radioactive rocks splitting water into oxygen and hydrogen. Then there is the process of serpentinisation, in which groundwater reacts with iron-rich minerals in rock, such as olivine, to create iron oxide and hydrogen gas. Most geologic hydrogen hunters have this serpentinisation process in their crosshairs. The thinking is that places with a lot of iron-rich rock may also generate lots of hydrogen, says Viacheslav Zgonnik, whose company, Natural Hydrogen Energy, drilled a well in search of the gas in Nebraska last year. The canniest prospectors look for an area of iron-rich rock capped with an impermeable layer, so the precious fuel might be sealed in and build up underground.

“The Hoarty NE3 wellhead in Nebraska. photo: Hyterra”

Other companies looking for hydrogen in the US Midwest, including Koloma and HyTerra, are following this rationale. Similarly, Gaucher says newly identified deposits in the Pyrenees mountains straddling France and Spain that could contain tens of millions of tonnes of hydrogen may occur due to a bulge of iron-rich mantle rock sitting unusually close to the surface. In Oman, this iron-rich geology is even more accessible thanks to the region’s unique tectonic past.  Just under 100 million years ago, the tectonic plate beneath the Arabian Sea collided with another under the land.

“A large fairy circle in Brazil that leaks hydrogen is curiously devoid of vegetation”

Such events usually result in the crust being forced down into the mantle, but here it was thrust upwards, a process known as obduction. The Hajar mountains are the result. They are the largest exposure of mantle rock on the planet, mostly made up of iron-rich peridotite that you can’t help but walk upon. During my visit, in a valley strewn with boulders of this green and white-streaked material, we took off our shoes to cross a stream flowing over rocks that were once on the boundary between Earth’s mantle and crust.

“Hydrogen seepages might explain mysterious depressions often called fairy circles. Some are more than 1km wide in this lidar image of coastal N. Carolina.”

How to find natural hydrogen
There may be another way to identify areas ripe for hydrogen extraction. A session at the American Geophysical Union conference last December featured research on using machine learning to identify rings of bare soil – sometimes called fairy circles – in satellite images. Joachim Moortgat at Ohio State University, who contributed to that work, says hydrogen has been measured in soil at more than 50 such circles, although the relationship between the gas and these mysterious formations remains unclear.

Despite the excitement, however, geologic hydrogen would have shortcomings as a fuel, especially when it comes to being transported long distances. For starters, the gas is explosive. And because it occupies large volumes, it needs to be compressed or converted into other chemicals, such as liquid ammonia, before it can be easily moved. We might need to build new pipelines to carry it from remote locations to ports or cities.

It would help if we could avoid relying on happenstance accumulations of hydrogen and instead stimulate the ground to reliably produce the gas in more convenient areas. That is what a number of researchers and companies are now working on. The US Department of Energy (DoE) is involved too, putting up $20 million for such efforts. The idea is to explore ways of speeding up the serpentinisation process and so conjure hydrogen from the ground. “We can greatly expand the regions from which this resource will be available,” says Doug Wicks, who directs the DoE programme.

With their well-understood geology, iron-rich peridotite rock and clear evidence that hydrogen is bubbling from the ground, the Hajar mountains are an ideal place to test the idea. Following a workshop involving the DoE and the Omani government in November 2023, there are now plans to drill the world’s first stimulated hydrogen well here later this year. Alali, who has played a central role in coordinating this work, showed me one of four possible sites for the well. We drove through the alleys of a small town called Hailain – this was where our vehicle almost got stuck – and out into a valley. Several of the pools bubbling with hydrogen were covered by what resembled a layer of ice (pictured, below). This was actually a powdery mineral film formed from reactions between calcium leached from the peridotite and carbon dioxide in the air.

“Mineral films coat pools of water in the Hajar mountains in Oman”

Alali told me the pilot stimulation project will involve drilling at least one borehole to a depth of between 400 and 600 metres. The rate of geologic hydrogen production will be measured and the team will then try different methods of stimulating the hydrogen-generating reaction, including injecting water and heating the rock. Adding chemical catalysts is another option, though not one the researchers plan to test yet. “There really are a lot of knobs to turn,” says Alexis Templeton at the University of Colorado Boulder, who is the lead researcher on the project. She says the goal is to increase the rate of hydrogen production by 10,000, the point at which it would be commercially viable.

Can we stimulate natural hydrogen production?
To help get there, the team will try a novel strategy for breaking up rocks deep underground to increase the surface area exposed to the injected water. The method, developed by Eden GeoPower, is akin to fracking for natural gas, but with electricity instead of water. Sending a high-voltage current between electrodes lowered into the ground should heat microscopic pores in the rock, causing them to expand in “a spiderweb of lightning fractal patterns underground”, says Paul Cole, Eden GeoPower’s head of subsurface engineering. There are several reasons the project may not work as well as hoped. The pores in the rock could get clogged, trapping the hydrogen. The required energy input could end up being unfeasibly high.

Plus, Templeton says there are communities of bacteria living in Oman’s rocks that feed on hydrogen. No one knows how they will react when the amount of hydrogen increases. It is possible their numbers will swell, creating a mob of microbes that gobble up much of the fuel before it can be collected. This may not be an issue for projects drilling in hotter, deeper wells, but in Oman “the rocks are alive”, says Templeton. Outside researchers say the goal of upping the rate of hydrogen production in such wells by 10,000 is feasible, but there is no guarantee of success. “It will take some clever chemistry to make it work,” says Toti Larson at the University of Texas at Austin, who isn’t involved in the project.

There are also some environmental risks. For instance, it is unclear how much water the project will require. Using substantial amounts in an arid place like Oman could raise eyebrows, although Alali says the plan is to use non-potable wastewater or groundwater for the tests. We also must be alive to the risk of small earthquakes from injecting water, says Mengli Zhang at the Colorado School of Mines, who also isn’t a part of the work. If all goes well, Oman, a nation known for its oil and gas, could find itself leading the field of geologic hydrogen. The impacts might even spread far beyond its borders and give our efforts to power the planet without fossil fuels a serious boost. “There are a lot of really smart people working on this now,” says Wicks. “I’m expecting some audacious and potentially earth-shattering ideas about how to get hydrogen out of the ground.”

The hydrogen rainbow
Hydrogen may be a colourless gas, but those in the industry think of it as coming in a number of shades depending on its environmental credentials.
Black: This hydrogen is produced by degassing coal. The process produces a lot of carbon dioxide and is no longer common.
Grey: This method starts with natural gas and generates hydrogen and carbon dioxide, making it a significant producer of greenhouse gas. It is by far the most common way to make hydrogen because it is cheap.
Blue:  Just like grey hydrogen, except the carbon dioxide is captured and stored underground, meaning it contributes less to global warming.

Turquoise: A relatively new innovation, this approach breaks down natural gas into hydrogen and solid carbon, meaning no carbon dioxide is emitted. It is potentially cheaper than green hydrogen (below), but the technology needs development.
Green: The most environmentally friendly way to make hydrogen. This method uses electricity generated from renewable sources to electrolyse water into oxygen and hydrogen.
Gold: Sometimes called white hydrogen (or natural or geologic hydrogen), this is when the gas occurs naturally deep underground and could be harvested through drilling, with no need to expend energy on synthesis. This potentially makes it a highly promising clean fuel, if enough of it can be found and collected.”

A hydrogen fuel revolution is coming – here’s why we might not want it
by Adam Vaughan  /  3 February 2021

“If hydrogen fuel is the future, it has been for quite some time. In his 1875 novel The Mysterious Island, Jules Verne imagined the element replacing coal as a fuel, split out of water to “furnish an inexhaustible source of heat and light”. Similar noises were made in the 1970s oil crisis, when hydrogen was touted as an alternative fuel for cars. And then there was US president George W. Bush in 2003, latching on to a new enthusiasm for hydrogen vehicles during the first wave of real concern about climate change. “We can make a fundamental difference for the future of our children,” he said.

Now hydrogen is back – again. From the US to Australia, and the European Union to China, the past year has seen an almost daily torrent of multibillion-dollar government funding pledges, tests of new technologies from trains and planes to domestic boilers, industry statements and analyses, and championing by leaders such as UK prime minister Boris Johnson. “We’re finding it hard to keep up with,” says Simon Bennett at the International Energy Agency. “The idea of a hydrogen economy is not new,” says Martin Tengler at analysts Bloomberg New Energy Finance. “Now we’re in another hype cycle. The question is: is it different, or not?” Tengler is one of many who thinks it is. Meanwhile, another question hangs much heavier than hydrogen in the air: is it really a clean, green fuel to help combat climate change? Or does the significant lobbying of fossil-fuel interests for a hydrogen economy indicate other priorities?

Hydrogen is the lightest element in the universe and the most abundant. On paper, it has a lot going for it as a fuel. Although it rarely exists on its own on Earth, it can be produced using clean electricity to split essentially inexhaustible water, producing only oxygen as a by-product. Once made, hydrogen acts as a chemical energy carrier, rather like oil or gas, that can be piped or transported to where it is needed. It stores three times as much energy per unit of mass as conventional petrol, and when it “burns” in air – releasing that stored energy – it simply combines with oxygen to produce water again. In that sense, it is the ultimate green fuel.

Perhaps the most notorious attempt to use hydrogen to change the world ended with the fiery demise of the German airship Hindenburg in New Jersey in 1937, when the hydrogen gas used to give it buoyancy caught fire. Technology for the safe storage of hydrogen has since come on in leaps and bounds. In recent decades, the idea of creating a “hydrogen economy” has focused on developing liquid hydrogen as an alternative green fuel, mainly for cars. One thing that is different now is how hydrogen is being touted as a way to decarbonise “hard-to-abate” sectors that are difficult to power directly with clean electricity. These range from long-distance road haulage, aviation and shipping to naturally carbon-intensive industrial processes such as steel and petrochemical production.

Green, grey or blue?
The past two years of climate pledges by businesses and governments, from the UK to China, has made clear that even these industries will have to transform if we are to meet the overarching goal of net-zero carbon emissions by mid-century. And hydrogen figures big in that goal: the European Commission’s Joint Research Centre says that between 10 and 23 per cent of the EU’s final energy consumption could be covered by hydrogen in 2050; the energy company Shell puts the figure at 10 per cent globally by 2100. Meanwhile, the rapidly falling costs of power from wind and solar farms has made the large-scale, clean production of hydrogen using clean electricity plausible. The problem is that the vast bulk of hydrogen isn’t currently made that way. Humanity already produces around 70 million tonnes of hydrogen each year, mainly for use in making ammonia fertiliser and chemicals such as methanol, and to remove impurities during oil refining. Some 96 per cent of this hydrogen is itself made directly from fossil fuels – mostly natural gas, followed by coal and then oil. This overwhelmingly uses a process known as steam reformation that releases carbon dioxide.

Only 4 per cent of hydrogen is made in the way Jules Verne envisaged, using electrolysis to split it out of water. Much of the electricity to supply even that measly share of the hydrogen market comes not from green sources, but from fossil fuel power plants. Far from being green, the hydrogen produced globally today has a carbon footprint on a par with the UK and Indonesia combined, says Tengler – about 830 million tonnes of CO2 annually. That brings us to the strange point where transparent hydrogen gets colourful, at least linguistically. “Grey” hydrogen is so-called because it is made from fossil fuels using steam reformation. It costs about $1 a kilogram. “Blue” hydrogen typically “buries” the emissions associated with producing it using carbon capture and storage (CCS) technology – an approach which exists, albeit only on a pilot scale so far – for about $2 per kilogram at the cheapest. Finally, there is “green” hydrogen, produced by electrolysers running off renewable electricity. For the most part, this costs upwards of $4 a kilogram.

When it comes to decarbonisation, “there’s no point in grey hydrogen”, says Rob Gibson at National Grid ESO, which runs the UK’s electricity transmission network. But a move towards large-scale green hydrogen production would be very costly, says Evangelos Gazis at Aurora Energy Research in Oxford, UK. This is where blue hydrogen comes in. “If we want to reach scale, probably [blue] will be inevitable,” says Gazis. Others, such as Ralf Dickel at the Oxford Institute for Energy Studies, make the case that blue hydrogen is needed in the short term because using renewable electricity to displace coal and gas power plants achieves deeper CO2 curbs than using it to make green hydrogen. Four of the biggest existing blue hydrogen schemes are in North America, and the UK government is funding three trial projects. Some advocates argue that such schemes will be an enabler for green hydrogen, helping to build infrastructure to tackle the fiddly question of getting hydrogen to where it is needed. Others see blue hydrogen very differently. Because it still involves extracting gas, oil and coal, Friends of the Earth Europe has branded it “fossil hydrogen”, a lifeline for struggling fossil fuel firms.

Certainly, the sponsors of a group such as the UK’s All-Party Parliamentary Group on Hydrogen are a who’s who of fossil-fuel interests, including Shell, petroleum refiner Equinor, gas network firm Cadent and gas boiler-maker Baxi. But Tengler doesn’t buy the argument that such support is a cover for business-as-usual. “Just because they are fossil-fuel companies, we shouldn’t exclude them from the future,” he says. There is, however, the undeniable problem that blue hydrogen doesn’t capture all the CO2 released while making the gas. A first CCS stage removes between around 50 and 70 per cent. Adding a second, costly step takes that to 85 to 90 per cent, with some pioneering projects aiming for more. Equinor’s H2H Saltend blue hydrogen scheme near Hull, UK, should capture 95 per cent of CO2 using an alternative to steam reformation known as autothermal reforming.

Still, for most blue hydrogen schemes, at least 10 per cent of emissions aren’t captured. Tengler calculates that offsetting such carbon emissions with reforestation would require an area between the size of England and that of Spain, which is about four times as big. The scale of offsetting depends on what fossil fuel the hydrogen is extracted from and how much is being made by 2050. He still thinks it is worth it, on the basis that using blue hydrogen still creates fewer emissions than burning coal, oil or gas. “There is that portion of emissions that just don’t get captured. Does that mean we don’t do it? I would say we still probably should. If there’s the option of blue or nothing, then do blue,” says Tengler. Jan Rosenow at the Regulatory Assistance Project, a non-profit organisation that works to expedite a clean-energy transition, disagrees. He likens blue hydrogen to the coal industry’s attempts 15 years ago to promote “clean coal” plants fitted with CCS. That never happened, because the rapidly falling cost of alternatives including renewables rendered it uneconomical.

If not blue hydrogen, then what are the prospects for green hydrogen? The EU, for example, has less than 1 gigawatt of electrolyser capacity now, but in July 2020 it set ambitious targets of 6 GW by 2024 and 40 GW by 2030. Germany is working with Morocco to build a project using solar power. A dizzying cast of big companies have entered or are planning to enter the green hydrogen fray, including oil giants Repsol and Shell and the world’s biggest offshore wind farm builder, Ørsted. Spanish electricity company Iberdrola is building a solar power plant to create green hydrogen in 2021, initially for conventional uses such as making fertiliser. “When we develop enough technology and scale, we can go for other sectors like the hard-to-abate, lorries, probably planes,” says Samuel Perez at Iberdrola. Analyst Rystad Energy, based in Norway, counts 60 GW of green hydrogen projects planned globally – but it expects only half will appear by 2035 due to high costs. Closing the gap between the price of green and grey hydrogen will take time. Producing one kilogram of hydrogen requires about 50 to 55 kilowatt-hours of electricity (a medium-sized UK home uses about 8 kWh a day on average) and 9 to 10 litres of water. Up to 86 per cent of the costs of green hydrogen are for electricity to power the electrolysers. But wind and solar power costs have dropped rapidly in the past decade, and are expected to fall further.

The electrolysers themselves account for the remaining cost. They are an old technology, but one that its makers claim can be made cheaper. Graham Cooley at UK manufacturer ITM Power says a 10 megawatt electrolyser costs half as much as it did three years ago, and the price will fall further, especially because of developments in China, now a major manufacturer of these devices. Duncan Clark at Ørsted, which is in phase two of its Gigastack project using a wind farm off the Yorkshire coast of the UK to supply green hydrogen to a nearby oil refinery, says the technology is at a “special moment”, akin to where offshore wind power was a decade ago before costs dropped dramatically and installations proliferated. “Only a few things are big and interesting enough to rival offshore wind, and green hydrogen is one of them,” he says. Even so, government interventions are likely to be needed, such as subsidies to make green hydrogen cheaper and carbon taxes to make grey hydrogen more expensive. “The market in the next 10 years is likely to be policy-driven. There will be a strong reliance on public funding for projects,” says Bennett.

Carry on regardless?
Hydrogen’s success may in the end be decided by society’s willingness to pay for it. Green hydrogen will need billions, either through taxation or energy bills: Bloomberg New Energy Finance estimates that it will require $150 billion over the next decade globally to bring the cost down to a competitive level. “Someone has got to pick up the bill,” says Bennett. Nonetheless, Bennett is optimistic that the current round of hype over hydrogen is different. This is partly because of the near-unanimity from different industries on its potential and partly because, for many hard-to-abate sectors, we have few alternatives on the table. “If we don’t have [clean] hydrogen available by 2030 or 2040, we think we’re going to be in a sticky place for some of these sectors,” says Bennett. “There are certainly risks on being overly bullish on the future hydrogen economy,” he says. “But I think it’s a bad time to be an out-and-out sceptic because there’s clearly momentum and funding going into projects in the short term regardless.” The question today no longer seems to be if hydrogen will help us fight climate change, but a matter of whether it ends up as the star turn or just a bit player.

“A train powered by a hydrogen fuel cell near Vienna, Austria, in 2020”

Six uses for Hydrogen: Trains, Planes and…
The glossiest of many new uses touted for hydrogen is in transport. Hydrogen cars have faltered before, as oil prices yo-yoed and battery powered electric cars emerged as a viable technology. But for larger vehicles, the batteries required are big and heavy, possibly creating an opening for hydrogen. Two hydrogen fuel-cell trains built by the firm Alstom were put into commercial service in Germany in 2018, and one in Austria in 2020. The UK has also been trialling this approach on its rail network.

“Airbus aims to get zero-emission hydrogen planes flying by 2035”

Hydrogen’s high energy content in relation to its weight has also caught the eye of plane-makers. In the UK, 2020 saw the flight of a six-seater hydrogen passenger plane, while European aerospace firm Airbus unveiled three concept hydrogen planes. “When we go to larger commercial aircraft-type applications, we see the need for hydrogen, because in very simple terms it has thousands of times more energy per kilogram than even the best batteries today,” says Glenn Llewellyn at Airbus. Julian Renz at green aviation company ZeroAvia, which undertook the six-seater test flight, says he thinks hydrogen-powered planes will be cheaper to maintain than battery ones, because of the limited life cycle of batteries.

“A hydrogen car refuels at a filling station in Germany”

While most analysts think battery electric vehicles are the future for passenger cars, some car-makers believe that the faster refuelling of hydrogen vehicles will win the day in some places. “I definitely see a market for hydrogen passenger cars,” says Mark Freymüller at Hyundai. Under a European scheme, in which Hyundai is offering cars on a pay-per-use model, the vehicles are fuelled solely with green hydrogen. “It is important to be emission-free,” he says. Hydrogen trucks may also prove more viable than battery electric lorries, because of the size and weight of battery needed to power a lorry.

“In 2019, a project heated homes in the Netherlands
with 100% hydrogen for the first time”

Home Heating
Many uses for hydrogen are mooted, but some are far from guaranteed to materialise. One is decarbonising home heating, with proponents arguing that countries, including the UK, could repurpose existing gas pipe networks to carry hydrogen and swap natural gas boilers for ones capable of burning hydrogen. Leeds in the UK has been mooted as an early candidate for switching entirely to hydrogen instead of natural gas for heating and cooking, with a 2016 report by the local energy network finding the idea “technically possible and economically viable”. In November, the UK government said it would support a village-scale hydrogen heating trial by 2025. Sceptics say it would be more efficient to use renewable electricity directly with heat pumps to warm homes, rather than losing energy by converting it to hydrogen first. A recent report by Jan Rosenow and a team at the UK Energy Research Centre concluded that there is so much uncertainty about hydrogen’s role in decarbonising heat that other options should be the UK’s priority in the next decade. These include networks that pipe heat to many homes from a large, central source such as an industrial plant, energy efficiency improvements and heat pumps.

Supporting the Grid
Firms running electricity grids like hydrogen. The National Grid ESO in the UK says it must be deployed if we are to achieve net-zero emissions, and sees hydrogen supplying the flexibility that natural gas does today, by providing electricity when wind and solar output is low, or heating during cold snaps. “It has the potential to provide a lot of flexibility,” says Rob Gibson at National Grid ESO.

Heavy Industry
Steel is one of the world’s biggest carbon emitters, partly due to the coking coal used in the production of the metal from iron ore. In August, operations started at a steel-making plant in Sweden to use hydrogen instead of the coal, which produces water instead of carbon dioxide. The project, called HYBRIT, aims to make fossil-free steel commercially available by 2026. Any scale-up will require green or blue hydrogen (see main article) to make the switch worthwhile. Oil refineries are one of the biggest users of hydrogen today, mainly to lower the sulphur content of diesel fuel. That is partly why projects such as Ørsted’s Gigastack hydrogen production plant in the north-east of England have sited an electrolyser, powered by an offshore wind farm, next to a refinery.

Making Green and Blue
Shell is among the companies exploring whether the port of Rotterdam in the Netherlands could host the world’s biggest green hydrogen scheme. Spanish oil firm Repsol is eyeing the possibility of making green hydrogen next to its refineries. Far bigger green hydrogen projects are being floated, such as Australia’s vast “Asian Renewable Energy Hub” to use renewable electricity to produce hydrogen for use domestically and for export to Asia. Blue hydrogen projects, which use natural gas to make hydrogen but capture most of the carbon dioxide that is usually released in the process, include Equinor’s Saltend plant in the UK. The company hopes to make a final investment decision on this in 2023. It has applied for UK government funding. Other blue hydrogen proponents include fossil fuel companies such as Woodside, Australia’s biggest oil and gas producer, and the government of Alberta in Canada, which hopes to use the approach to reduce CO2 emissions in the state, which is better known for its highly polluting tar sands oil fields.

Devil of a Detail
While hydrogen has many potential advantages as an energy carrier (see main story), it poses some significant problems. While containing a lot of energy per unit mass (high gravimetric energy density), hydrogen takes up a lot of space (low volumetric energy density). What’s more, hydrogen molecules are so small they can leak out of a container. Both factors make storing and moving it problematic. “Hydrogen is a devil of a thing to transport,” says Thomas Baxter at the University of Aberdeen, UK. “That’s why most hydrogen plants are adjacent to the use.” It means visions of countries with big renewable electricity generation resources becoming exporters of “green” hydrogen are just that for now, visions. Such ambitions are a key plank, for example, of Australia’s National Hydrogen Strategy, published in November 2019, but are seen as a long way off, given the volumes required and the extra costs of liquefying hydrogen and shipping it. “For the time being, we would expect local production is where all the projects will be,” says Simon Bennett at the International Energy Agency. To fulfil hydrogen’s potential, more transport capacity will be needed generally, be it by tanker truck, ships or pipes – many of which will need upgrading to carry hydrogen without leaks.”


“The electrochemical cell separates lithium ions from seawater
while also producing valuable hydrogen and chlorine gas”



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