Whisper it softly, but a clean, green solution to the energy industry’s most intractable climate conundrums may be in sight — and it is almost as old as time itself.

Many experts believe that the transport industry can never be decarbonised using renewable energy alone; that heat cannot be produced on a massive scale without burning hydrocarbons; and that intermittent wind and solar will never be able to cover the so-called seasonal gap in winter, when there is simply not enough sun or wind to produce the energy needed to meet peak demand, no matter how much is stored in batteries or pumped hydro plants.

If only the planet had an affordable, emissions-free version of a fossil fuel — one that could be stored indefinitely, can generate both electricity and heat (with or without fire), and be able to power trucks, trains, ships and planes.

Well, such a fuel already exists and it can be produced on an industrial scale using little more than renewable energy and water. It also happens to be the most abundant element in the universe.

Hydrogen production

Hydrogen cannot be found on Earth in its pure state (H₂). It has to be extracted from naturally occurring molecules — most notably water (H₂O) or natural gas (methane) (CH₄).

Hydrogen is already produced in industrial quantities today and used mainly to remove sulphur from crude oil, to thin out viscous fossil fuels such as shale oil, and to produce ammonia for fertilisers. About 95% of this hydrogen is extracted from natural gas using a process called steam methane reformation, which releases large amounts of CO₂ into the atmosphere — 11-12 tonnes for every tonne of H₂ produced. Due to its dirty nature, this is known as grey hydrogen.

But hydrogen can also be extracted from water using a machine called an electrolyser, which uses an electric current to split H2O into its constituent parts. If renewable energy is used, the gas has a zero-carbon footprint, and is known as green hydrogen.

The problem is that, at the moment, grey hydrogen is much cheaper to produce than green hydrogen.

According to Ben Madden, director of UK-based low-carbon energy consultants Element Energy, grey hydrogen costs £1-2 ($1.30-2.60) per kg to produce, while grid-powered green hydrogen costs somewhere between £8-10/kg, depending on the price of electricity.

But large-scale water electrolysis is in its infancy — comparable to where solar power was in the 1980s, some say — and the price is expected to drop rapidly in the coming years as the technology matures and scales up.

Madden points out that one of the leading electrolyser makers, Norway’s Nel Hydrogen, recently declared a price below €500 ($585) per kW for a proposed 1MW system. “That’s a really low number for anything in the energy sector,” he says. “It’s almost getting to the cost per kW of grid connection in some of the more complicated renewables schemes.

“Effectively, the capital cost of electrolysers is disappearing from the problem. Once you’ve got to scale, the question really is the price of the electricity.”

In places where electricity is cheap, water electrolysis could already produce hydrogen that would be a cheaper fuel than petrol or diesel, says Anne Kleczka, head of car maker BMW’s Hydrogen Fuel Cell Technology Project.

“In Norway, for example, they could produce green hydrogen made from hydropower and sell it without subsidies at the [filling] station for €4.50/kg, which is half the price of petrol per 100km,” she tells Recharge.

Kleczka points out that in countries such as Germany and China large amounts of renewable energy are curtailed when the grid cannot cope with the amount of wind and/or solar power coming on line. This energy could instead be used to produce green hydrogen.

“If you used the surplus [renewables] capacity in Germany in 2015 to produce hydrogen, then it would have been enough to run more than 150,000 fuel-cell electric vehicles a year,” she says. “And the surplus capacity is increasing year by year.”

Converting surplus wind and solar into hydrogen — particularly in the middle of the day when huge amounts of PV power are generated — could solve some of the biggest problems facing variable renewable energy.

Wholesale prices in places with high penetration of renewable energy can fall into negative territory when supply to the grid is higher than demand. But if there was a demand for this excess power — from hydrogen producers — prices would likely be higher and therefore more profitable for power producers. This could be hugely important at a time when utilities are complaining that building new solar and wind farms will be unprofitable due to low wholesale power prices.

In a similar vein, wind or solar projects in remote areas with excellent resource but high transmission costs could be built off-grid, with the generated energy instead used to produce hydrogen on site, which would then be transported via road or rail.

Hydrogen production could also provide a lifeline for older wind farms whose feed-in tariffs are due to run out after 15 or 20 years of production. Such projects are due to rely purely on the wholesale market for their income, but in some cases, this may not be enough to keep the wind farm solvent. Selling their energy to hydrogen producers via long-term power-purchase agreements could be a far more viable and profitable option.

Hydrogen as a transport fuel

Transport is expected to be the biggest market for this multi-purpose power source, at least in the short to medium term.

“The highest-value end-use market in energy is typically transportation,” says Matthew Tipper, vice-president for new fuels at oil giant Shell. “Power generation and heating are typically much lower-value markets for fuel suppliers.”

With countries such as the UK and France set to ban new petrol and diesel cars and vans by 2040 in a bid to reduce pollution and carbon emissions, renewable energy is clearly set to play a key role in providing the power for plug-in battery electric vehicles (BEVs). But less has been said about the role of fuel-cell electric vehicles (FCEVs) powered by green hydrogen.

Tipper tells Recharge that there are three reasons why consumers might prefer a fuel-cell car over a BEV — range, refuelling time and climate.

“You typically go quite a bit further on a cylinder of hydrogen than you do on a lithium-ion battery,” he says. “And the recharge time is very much faster. If you think when you charge your electric car at home, you’re getting maybe 10kW, a fast-charger is 50kW on a public charge post. A hydrogen car effectively charges at 3,000kW, so it’s a very, very much faster rate of charging.

“It’s also operating conditions. If the weather is particularly warm or particularly cold, you tend to find the hydrogen technology is more durable than the battery. You have less losses due to extreme heat and cold than you would find in a battery system.”

Kleczka points out that there is a fourth reason to choose a hydrogen-powered car — much of the world’s increasingly urban population, especially in Asia, does not have a garage or driveway where they can charge a BEV.

“I live in the centre of Munich and I have to look for a parking spot every evening — there is no possibility to charge at all,” she says. “If I would like to drive a zero-emission vehicle, the perfect solution would be to go to the filling station, as I do now.”

There is also a potentially problem with BEVs that has barely been addressed — the fact that users all tend to plug in their cars at the same time, when they get home from work.

“If you try to plug in 1,000 in a small area at the same time, you could have a nightmare, because you’d have to completely overhaul and upgrade the grid,” says Madden.

He argues that BEVs could struggle when they reach scale.

“Can they really offer something that a mass market customer will want, given that they will have a 30-minute charge time, even with a fast-charger? Is that acceptable to all of the mass market?

“The second question is, even if it is acceptable, will grids, will service stations, will all those types of places be able to cope with the deployment of that technology at scale? I completely accept the argument that electric vehicles are a more mature technology and are pushing ahead in a way that hydrogen cars are definitely not, but I do think there’s a question as to whether or not, some time in the 2020s, we will moderate our opinion on that.”

Kleczka says that BMW is not expecting to serially produce hydrogen cars before 2025. “The technology is still quite expensive — we need at least two generations of improvements and cost-downs to make a commercially successful offer,” she says. But she is in little doubt that they will be cost-competitive with BEVs within ten years.

Of course, no-one will buy a fuel-cell car if they cannot buy hydrogen at the pump. Tipper says that a sizeable network of hydrogen fuelling stations will have to be built before people will buy FCEVs at any kind of scale.

But this is not something that a company like Shell can do on its own, he tells Recharge.

“The best way this works is to form a coalition comprising fuel suppliers, people like Shell, and vehicle manufacturers, so Toyota, Daimler, BMW, Hyundai, Honda, companies with an interest in providing the vehicles — and essentially, very often in a public-private partnership to roll out both the vehicles and the infrastructure in a synchronised way,” says Tipper. “And they have to be synchronised in time, so supply meets demand, and they have to be synchronised in space. There’s no use me building a lot of stations in Hamburg if all the cars are in Munich.”

Tipper suggests that in the short term, the hydrogen available at Shell filling stations will be grey until the market grows — but that even that will bring emissions savings.

“The internal combustion engine is only about 30% energy-efficient, 70% of the energy is wasted,” he says. “A hydrogen vehicle is about 50% efficient. So on a well-to-wheel basis, you’re getting an almost 50% saving even when using natural gas as a feedstock, because it’s an efficiency gain in the drivetrain. So it’s important to recognise that using hydrogen from natural gas is a win in terms of CO₂ emissions. And then the challenge is to make it even better by moving into either biomethane or electrolysis.”

In Germany, the H2 Mobility organisation — a coalition of oil & gas and vehicle producers — is working to ensure that 100 hydrogen filling stations are open to the public by the end of 2018, with plans for 400 by the end of 2023. Importantly, the hydrogen on sale will be a 50-50 mix of grey and green hydrogen, stimulating production of the latter.

But Laszlo Varro, chief economist at the International Energy Agency, tells Recharge that he believes that fuel cells have already “missed the boat for personal transport” as they are so far behind BEVs in terms of commercialisation.

“But the high-energy density of hydrogen can come into the game for heavy-duty transport, where you need much more energy stored in the vehicle,” he says.

There seems to be a consensus in the industry that fuel cells will have the edge over batteries when it comes to buses, trucks and trains — due to the extra power hydrogen can provide.

And logistically, it makes sense too. A single hydrogen pump can be installed at a bus, truck or train depot and used to refuel an entire fleet. This can also be true of car or taxi fleets — for instance, Shell has installed a hydrogen pump at Toyota’s headquarters in Long Beach, California, to charge its Mirai fuel-cell cars.

Hydrogen-powered trains also promise to be cheaper than their diesel equivalents for non-electrified lines. The world’s first fuel-cell train — Alstom’s Coradia iLint — is due to begin passenger test runs in northern Germany early next year.

Hydrogen could also be used instead of diesel and heavy oil in the shipping industry. Large US warships are already powered by electric motors fuelled by diesel combustion, and there is no technical reason why the diesel could not be replaced with hydrogen and fuel cells.

“It is estimated that within ten years, fuel cells will be cheaper by far compared to a diesel-propelled [ship],” says John Olav Lindtjorn, global product manager for marine DC grid and energy storage at ABB.

Hydrogen could even be used in aviation. Liquid hydrogen has long been used by Nasa to power its rockets, but analysts argue this is not really feasible for commercial jetliners due to its relatively low energy density (by volume) compared to kerosene jet fuel. However, a carbon-neutral synthetic kerosene can be produced from hydrogen and carbon dioxide.

Hydrogen as energy storage

Hydrogen can be used as an electricity-storage medium, but in most cases, batteries are likely to be a better option.

Andrew Turton, principal analyst at UK-based research consultancy Delta Energy & Environment, says that battery systems are about 80% efficient at storing electricity, while the equivalent round-trip efficiency of hydrogen is 30-40%.

“If you look at the cycle from generating the renewable electricity through to compressing and storing the hydrogen, and turning it back into electricity — and compare that with a conventional battery system, batteries are clearly winning that task,” he says. “And it looks like batteries are going to keep reducing in price, especially with BEVs coming up.

“I think the point at which hydrogen would become more beneficial is when you start looking at long-term, large-scale storage.”

To cover the seasonal gap without resorting to fossil-fuel use, there really is no alternative to H₂, says Manfred Waidhas, Siemens’ head of business development, product management, technology & innovation for hydrogen solutions.

“We definitely need an accelerated and continued extension of renewables and then a logical consequence of that is that we will need a large-scale storage concept,” he tells Recharge. “There is nothing else like hydrogen that can cover more than 10GWh [of storage]. For example, in one single cavern you can store up to 1TWh of energy, which is not possible by pumped hydro or compressed air.”

Fuel cells in homes and cars can also be used to provide electricity to the grid, much in the way that plug-in BEVs will be able to help balance the grid. In Japan, where natural disasters are a serious threat to electricity supply, roughly 400,000 fuel-cell units have been installed in households to provide back-up power. “They also have a plug-in device that you can use [to link] the fuel cell in your car to the house,” says Kleczka. “It already works, and if you take the hydrogen capacity of a Toyota Mirai, for example, if you have a full tank, an average household can get about two weeks of electricity from it.”

Hydrogen as a heat source

There is a further hidden benefit to hydrogen that has attracted far less attention — heat.

When fuel cells convert hydrogen into electricity, they also give off a lot of heat, making them ideal candidates for so-called micro-CHP (combined heat and power) in buildings. For instance, the Radisson Blu hotel in Frankfurt has installed a fuel cell that will provide 3GWh of electricity and 2GWh of heat per year.

But perhaps hydrogen’s biggest contribution to the heating sector will be as a direct replacement for natural gas.

In many Western countries, natural gas is pumped along networks of pipes to homes and businesses, where it is used for heating (and cooking). It is entirely feasible that these networks — and all the gas boilers and burners — can be switched over to run on green hydrogen.

The idea that a country would replace its entire gas network to run on a different fuel is by no means far-fetched — the UK did just that in the late 1960s and 1970s.

Until then, the UK’s gas network used “town gas” — a mixture of hydrogen, methane, carbon monoxide and other hydrocarbons produced locally from coal. Then, after huge amounts of natural gas were discovered under the North Sea, the UK began converting its network to this more efficient, cheaper gas — replacing more than 40 million appliances in the process.

And since 2002, the UK has been actively replacing the original town-gas iron pipes with cheaper, more reliable polyethylene ones, a process due to be completed by 2032. These plastic pipes are able to transport 100% hydrogen. (It is also possible to enable more porous types of natural-gas pipe to transport the smaller molecules of pure hydrogen by injecting a special resin.)

Last year, a feasibility study was carried out by Northern Gas Networks into whether Leeds — a city of 780,000 in northern England — could replace its natural-gas supply with pure hydrogen. The 375-page report, H21, concluded that it was feasible financially and technologically through steam methane reformation and carbon capture and storage.

This report prompted the UK government to launch its own £25m feasibility study into whether hydrogen — which is not more flammable than gas, but is easier to ignite — will be safe to use in people’s homes.

It is also possible to inject up to 5% pure hydrogen into the existing natural-gas network without any changes needed to pipelines, boilers or other appliances, and this actually makes the gas more energy-intensive.

“You could convert the whole UK network to hydrogen or you could convert certain parts of the distribution network to hydrogen where it makes sense — where we can produce the hydrogen and where we can get rid of the carbon, for example, Leeds — and leave the other bits on natural gas or biogas,” says Turton. “The current thinking is there may not be a single gas network, but it will be a gas network which operates perhaps with different gases in different places.”

Conclusion

So hydrogen clearly has vast potential to help the world reduce its carbon emissions — in tandem with the increased roll-out of wind and solar and the electrification of the heat and transport sectors.

As FCEVs become cost-competitive with BEVs some time in the late 2020s, and the amount of wind and solar in the system increases, the electrolysis process is expected to scale up dramatically, with the price of green hydrogen due to fall accordingly. Then green H₂ can start to be used on an industrial scale for heat and long-term storage, possibly from around 2030.

Of course, this will all require a concerted effort by a wide range of players, including regulators and governments.

As Kleczka points out: “The technology is already available. All that’s lacking is the vision and business plan to make this hydrogen-based energy system happen.”

Transition

Hydrogen: the green-energy problem solver