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 , 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 , tests of new technologies from trains and planes to domestic boilers, , 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.
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“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.
“Is hydrogen a clean, green fuel – or does fossil-fuel lobbying suggest a different story?”
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 (see “Six uses for hydrogen“).
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 could be covered by hydrogen in 2050; the energy company Shell puts the figure at .
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 , 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 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 . 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 (see “A devil of a detail“). 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 are a who’s who of fossil-fuel interests, 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 , with some pioneering projects aiming for more. Equinor’s 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 , 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.
“Offsetting carbon emissions from hydrogen might need a forest the size of Spain”
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 , 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 .
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. 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 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.
Six uses for Hydrogen
1 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 , and one in Austria in 2020. The .
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.
2 … AUTOMOBILES
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.
3 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 finding the idea “technically possible and economically viable”. In November, the 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 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.
4 SUPPORTING THE GRID
Firms running electricity grids like hydrogen. The National Grid ESO in the UK says , 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.
5 HEAVY INDUSTRY
Steel is , partly due to the coking coal used in the production of the metal from iron ore. In August, 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 in the north-east of England have sited an electrolyser, powered by an offshore wind farm, next to a refinery.
6 MAKING GREEN AND BLUE
Shell is among the companies exploring whether the 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 “” 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 . Other blue hydrogen proponents include fossil fuel companies such as , Australia’s biggest oil and gas producer, and the , 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.
A 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.
