Can “green” hydrogen production reach the scales and costs needed for net zero?

So far the costs of green hydrogen production have involved price hikes that businesses find hard to stomach – but some companies are making headway in providing energy on terms that are as compelling for present-day economics as they are for the future of the planet.

Anna Demming

Using hydrogen as a fuel – trading in the CO2 produced by burning fossil fuels for a waste product as benign as water – may sound a no-brainer when it comes to sustainably powering the planet. What is more, hydrogen is a gas the chemical industry is already familiar with – tens of millions of tonnes of hydrogen are produced globally each year, largely for synthetic fertiliser among other products. The catch is that most of this hydrogen is produced from natural gas and that production is accompanied by the emission of CO2

Hydrogen produced from natural gas is now termed “grey” hydrogen to distinguish it from its “green” counterpart – hydrogen produced by methods that do not emit as much CO2. In its 2019 report the International Energy Agency estimated global hydrogen production to be responsible for the emission of 830 million tonnes of CO2 each year, “equivalent to the CO2 emissions of the United Kingdom and Indonesia combined.”

Some systems for producing hydrogen from fossil fuels come with a carbon capture component to mitigate the impact of the CO2 emitted, promoting them to “blue” hydrogen. However, although carbon capture and storage (or use) aims to capture 90% of the CO2 emitted, a recent study by Mark Jacobson, a professor in the Department of Civil and Environmental Engineering at Stanford University in the US, suggests that once elements of the process such as the energy needed to run the equipment and upstream CO2 emissions are taken into account, the net carbon capture is nearer 11% over 20 years and 20-30% over 100 years. 

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Clearly “green” hydrogen is the ideal. However, while the prices for these alternative sustainable methods for hydrogen production, such as the electrolysis of water, are on a downward trajectory to compete with grey hydrogen, this is unlikely to happen before the end of the decade. According to a BloombergNEF analysis in August 2023, the cost of hydrogen production currently works out at $0.98-$2.93 per kilogram for grey, $1.80-$4.70 per kilogram for blue and $4.50-$12 per kilogram for green. “Let’s face it – it’s not affordable, it’s just not,” says Sabin Nair, CEO and founder of hydrogen technology company Origin 21. “How do you get a normal person to adopt a technology when it’s just not within their means?” 

As more and more accept the idea that the status quo of energy provision comes at too great a cost to the planet, demands are mounting for more sustainable alternatives. A host of companies across the world, from small new start-ups like Origin 21 to large multinationals like EDF, are striving to tackle the chemical and engineering challenges of a range of production processes, as well as the gulf separating current systems from the economies of scale of mass production with the aim of fuelling the world at a cost that is acceptable on all fronts.

Bringing costs down

By far the most popular route to green hydrogen at present is electrolysis, whereby water molecules ionise into negatively-charged oxygen “anions”, and positively-charged hydrogen “cations” (essentially just a proton since a hydrogen atom is a single positively-charged proton with a single negatively-charged electron). Applying a potential difference between two electrodes in water sends the protons to the negatively charged cation-attracting electrode (the cathode). Here they acquire their missing electrons from the electrode and form hydrogen gas, which then bubbles up for capture. Meanwhile the oxygen anions make their way to the positively charged anode where they deposit their excess electrons and form oxygen gas. 

Simply recombining the oxygen and hydrogen produces water again, alongside a lot of energy from the exothermic reaction. A sustainably powered electrolysis fuel cell produces green hydrogen that provides a useful stash of ready energy on demand to cover intermittent energy sources such as solar and wind power, so long as the hydrogen produced can be safely stored

Many of the major players in the energy market are working to produce green hydrogen from electrolysis, including EDF whose Tees Green Hydrogen project proposes to harness energy from the local wind farm at Teeside, Newcastle for its electrolysis plant. EDF hopes to produce 7.5 MW worth of hydrogen in the initial phase, with future phases delivering up to 300 MW by 2030. Other companies are primarily targeting smaller-scale energy provision, such as Bristol based Oort Energy, which has developed electrolytic fuel cells that are, according to the company, “the lowest cost, most efficient technology on the market for the 1-10MW range”, thanks to some finessing of the basic design. 

The Oort Energy fuel cell is based on a polymer electrolyte membrane (PEM) – “a solid plastic salt” as CEO Nick van Dijk describes it, where salt refers to any compound made up of a cation and an anion, of which regular sodium chloride or table salt is a common example. The membrane allows the hydrogen cations to pass through, but separates the hydrogen and oxygen gases produced preventing them from mixing, which can be explosive.

Nick van Dijk, CEO of Oort Energy

As van Dijk highlights, the use of PEM has a number of efficiency advantages. For instance, the electrodes can be positioned closer together, lowering the resistance to the current in the electrolysis. It is less prone to gas bubbles getting in the way of the current – known as “gas blinding”. And Oort Energy has developed a patented technology that allows it to use a particularly thin membrane without the gases produced mixing, which means still less electricity is needed for the same current. It has also designed out all of the expensive machined components of the fuel cell stack, while still ensuring they are pressure tight to contain the hydrogen, which further reduces costs.  A lot of work goes into increasing the electrode surface area where hydrogen production can take place while minimising the amount of catalyst used. 

Because no heating is involved, this kind of PEM is easy to switch on and off as the availability of renewable energy fluctuates, allowing it to handle the variations in weather found in countries like the UK. In addition, Oort Energy optimises the specifics of each system by region and country.

“The system in Lincolnshire is optimised for solar energy in Britain, where cost of system dominates the cost of hydrogen,” van Dijk tells Bristol Innovation Foresight. “In another region where the utilisation is higher (more sun), the system can be optimised for lower operating costs.” Oort Energy 1MW electrolysers are already due to be delivered to Morocco and South Africa later this year.

Many of the major players in the energy market are working to produce green hydrogen from electrolysis

PEMs are not the only approach to producing hydrogen from electrolysis. Hydrogen Future Industries (HFI), which backs technologies for green hydrogen production and storage, has invested in an anion exchange membrane water electrolyser, which saves costs because no rare earth metals such as iridium and platinum are used. They also use a special chemical process to attach the catalysts permanently to the electrodes, so that there is almost no catalyst washed away during the process, improving the durability of the fuel cells.

However perhaps the biggest efficiency saving comes from the wind turbines used to harvest energy in the first place, which the company describes in terms of a “proprietary rotor blade design with optimised cowling”, which “directs airflow across blades, creating multiple factor increase in wind speed.” The resulting wind turbine has three times the efficiency of regular propeller type wind turbines.

“Our costs will be $2 and below,” says Tim Blake, who is the biggest shareholder in the plc and CEO of several HFI subsidiaries. “So we’re cheaper than blue hydrogen.”

Weather-independent alternatives

The energy used to split water into hydrogen and oxygen need not be electricity. An alternative is to use heat, which can even be waste heat from some other process such as nuclear fission. Equilibrion is just one of the companies taking an interest in exploiting the vast quantities of heat released by nuclear fission power plants.

Green Hydrogen Technology claims its production plants can produce “up to 4,000 tons of climate-neutral hydrogen per year” from waste including plastics. Its plants heat the waste materials with a synthesis gas that releases hydrogen from the plastic alongside phosphates that can be used as fertilizer and CO2, which it suggests can be sold on for the manufacture of fizzy drinks.

There remains another process that produces hydrogen without any artificially supplied energy at all – natural, or “white” hydrogen. This is hydrogen that can be found in natural deposits that can be drilled for like natural gas. One such deposit was even stumbled upon during an attempt to drill for fossil fuels. A number of processes have been suggested to feed these hydrogen reserves, including water splitting into hydrogen and oxygen due to naturally occurring radioactive rocks, hydrogen lurking in the Earth’s core gradually making its way to the planet’s surface, and serpentinization, where silicates in iron-rich igneous rock react with water to form serpentinite, releasing hydrogen. The proportion each process contributes to these stashes of hydrogen is still not known. Viacheslav Zgonnik has been studying processes associated with natural reserves of hydrogen for 13 years, and is the founder and chief executive of a prospecting company for natural hydrogen – Natural Hydrogen Energy (NH2E). Accidental discoveries of hydrogen deposits by oil and gas companies have been rare so far for many reasons. Among these reasons, as Zgonnik tells Foresight: “They were looking in the wrong places (the right places for hydrocarbons, wrong for hydrogen), and they were not thinking such a light and diffusive molecule [could] be so abundant.” However in 2018, NH2E became the first company to successfully deliberately scope out and drill for hydrogen at a site the company identified in Nebraska in the USA.

Natural Hydrogen Energy (NH2E) is a company prospecting for natural hydrogen in the USA

“We don’t know exactly what is the quantity generated,” says Zgonnik, adding that the amount of hydrogen accumulated in the Earth and available for drilling is still under investigation. He highlights an as-yet-unpublished report by the US Geological Survey that suggests there may be as much as 5 trillion tonnes of accumulated hydrogen. “This is a lot!” says Zgonnik.  Notably these hydrogen stores are being constantly replenished by various geologic processes, making hydrogen effectively a renewable source of energy. However natural geological processes that produce hydrogen are slow and don’t necessarily occur at convenient sites for drilling. This has prompted Esti Ukar and Toti Larson at the University of Texas at Austin in the USA, in collaboration with researchers at the University of Wyoming, to look for ways of artificially expediting the process in rocks at more moderate temperatures and more accessible depths using catalysts, with some success in lab-scale analogues. The team was recently awarded a $1.7 million grant from the Department of Energy to investigate the feasibility of the approach.

Moving to market

There is keen interest in academia to understand the nitty gritty of the different processes that might sustainably produce hydrogen, which will doubtless help to improve their profitability further down the line. However, a setup that is little understood but demonstrably advantageous for reducing the need for CO2 emitting fuels may be compelling enough to just crack on and get a product to market. 

Doing something that is 97% better than the status quo is still better than waiting five years until hydrogen becomes affordable and acceptable mainstream

Sabin Nair, Founder of Origin 21

When Sabin Nair, founder of Origin 21, noticed that the gases produced by its water-based reactor cell could significantly extend the mileage of fossil fuel-based engines he was immediately excited and decided to focus on getting a product based on the reactor cell to market. 

Details of what is going on in the reactor cell and exactly what gases are produced are still being ironed out. However, it seems to exploit cavity microbubbles to dissociate the water molecules – a cavitation phenomenon that was already known but has not been demonstrated as efficiently as it appears to be in the Origin 21 setup.

Nair claims that the cell can lead to savings of up to 50% on fuels such as liquid petroleum gas and 99% on the carbon dioxide emitted, attractive enough to bring a model to market.

“Doing something that is 97% better than the status quo is still better than waiting five years until hydrogen becomes affordable and acceptable mainstream,” says Nair. “This is bridging the gap.” 

 Sabin Nair, founder of Origin 21

His sense of urgency for action is heightened by his experiences in South Africa. “I know the UK and Europe talk about a power crisis but a real power crisis is when you have rolling blackouts and the consequences of this are unemployment, [and] businesses closing down because it’s unaffordable to run generators all the time.”As well as the impact these inefficient generators have on the health and welfare of those local to the region, they also generate a lot of CO2 which affects the planet as a whole. With the Origin 21 reactor cells Nair sees a way to “give something back, something that would make a meaningful difference – more than just help the bigger corporates bring down their emissions to get to net zero.”

Getting a product to market also brings in money, an imperative for keeping a start-up afloat since funding can only take a business so far. Nair is also excited about the future possibilities the cell could provide for rural communities in developing countries, which could make use of their biowaste to feed into a sustainable system with the reactor cell, as well as later models that can provide engines for urban transport, such as mopeds. 

Oort Energy’s van Dijk also highlights the importance of funding, in particular government subsidies, which can help with the change from fossil fuel hydrogen to green hydrogen and the demand for lower costs.

“Essentially we must become like the car industry (efficient mass production),” he tells Foresight. “But demand drives mass production and mass production drives demand so today we are in a continuous loop.”

Care is needed not to encourage companies to get “lazy” and rely on grants and subsidies, which he suggests can prevent change. But on balance he suggests that at this stage government subsidies can be key to help kick-start change.

Anna Demming
Anna Demming / Writer

Anna Demming loves all science generally, but particularly materials science and physics, such as quantum physics and condensed matter. She began her editorial career working for Nature Publishing Group in Tokyo in 2006, and has since worked within editorial teams at IOP Publishing, and New Scientist. She is a contributor to The Guardian/Observer, New Scientist, Scientific American, Chemistry World and Physics World.