Does green hydrogen count as energy storage?

Every October, the publishers of the Oxford English Dictionary unveil the list of new words and phrases that they’ll be adding this year. It’s fair to say that the 2019 list – ‘chillax’, ‘easy-breezy’, ‘simples’ – will be far more fun that this year's. ‘Coronavirus’, ‘self-isolation’ and ‘social distancing’, surely?

But there is another phrase that arrived seemingly overnight in the energy sector in 2020. That is ‘green hydrogen’ and, suddenly, it was everywhere.

The concept of green hydrogen has been growing in popularity over the last couple of years, particularly in offshore wind. This is because hydrogen can be produced by the electrolysis of water, which is where electricity is used to split water into its two constituent elements: hydrogen and oxygen. If the electricity comes from renewable or low-carbon sources – such as offshore wind – then it’s called ‘green hydrogen’.

On that basis, it qualifies as energy storage. It takes unused electricity from one source and, rather than letting it go to waste, turns it into another form. This is why we have seen a series of large projects announced this year.

Ørsted, ITM Power, Element Power and Phillips 66 last month won £7.5m support from the UK government for the second phase of its Gigastack project. The group is looking to develop the first industrial-scale 100MW electrolysers and pair them with the 1.4GW Hornsea 2 offshore wind farm, which is set to complete in 2022.

Also last month, Dutch giants Shell and Gasunie unveiled a plan to build a huge green hydrogen project, called NortH2, in the Netherlands. This would be powered by a 3GW-4GW offshore wind farm in Dutch waters.

And this month, BP and RWE formed a consortium with Evonik, Nowega and OGE to develop the world’s first grid that would connect industrial users with producers of green hydrogen. The first phase of the 130km GET H2 Nukleus grid is due to export its first hydrogen by the end of 2022.

The roster of multinational partners interested across these three schemes shows just how seriously utility giants are taking green hydrogen. Fatih Birol, executive director of the International Renewable Energy Agency, has said: “Hydrogen can help overcome many difficult energy challenges. It can decarbonise hard-to-abate sectors like steel, chemicals, tuck ships and planes.”

But there are obstacles. The first is that hydrogen is an industry where there is little agreement over what is meant by specific terms, and so we could see other types of hydrogen projects seeking to call themselves 'green'. Here are our preferred definitions:

Green hydrogen: Produced by electrolysis using electricity from a renewable source such as wind, or another non-low-carbon source such as nuclear.

Brown hydrogen: Produced by taking a solid fossil fuel, such as coal, and combining it with oxygen and steam at high pressures and temperatures. This makes hydrogen, carbon monoxide and carbon dioxide, but also pollutes.

Grey hydrogen: Produced with a process called steam methane reforming. This is where methane from natural gas is heated with steam and a catalyst such as nickel. This makes hydrogen, carbon monoxide and carbon dioxide, but also pollutes. Around 70% of hydrogen produced in the world uses this method.

Blue hydrogen: This is the same as brown and grey hydrogen, but uses carbon capture and storage (CCS) to catch the carbon dioxide emissions and store them. Its backers say it makes those other processes carbon neutral.

Of these, green hydrogen is the only one we see as a form of energy storage. CCS can help reduce the environmental impacts of brown and grey hydrogen, but only green hydrogen takes excess energy from renewable sources and converts it into a useful product. But there are many conflicting definitions!

The other aspect is that it will take a long time for green hydrogen to drive the change Birol wants. It requires rapid commercialisation of the technology and vast amounts of renewable energy to create hydrogen on the scale needed. So yes, it is storage – and we'll be writing about it plenty! – but it isn’t a quick fix.