Grey hydrogen should act as a stepping stone for the development of blue and green hydrogen, according to panellists at a Reuters event.

Currently, 97pc of the hydrogen produced in the world is grey hydrogen — but a number of nations and regions around the world are developing hydrogen strategies because of the potential of the green and blue variety to act as low carbon fuels for the industrial and transport sectors.

“We do see blue and green hydrogen developing out of grey—it can be a good starting point,” says Paul Bogers, vice-president of hydrogen at Shell.

“We do see blue and green hydrogen developing out of grey” Bogers, Shell

Grey hydrogen production can be used to meet and build existing transport demand while the costs of blue and green—currently significantly higher—are brought down.

But it is likely grey hydrogen units will eventually be phased out because of the difficulty of retrofitting them with carbon-capture technology.

“Over time, putting carbon capture and storage on existing brownfield sites has limited capacity because you are unlikely to get net zero via that route,” says Bogers, noting grey hydrogen could instead be used as a bridging fuel until blue and green production units come online.

However, it is not a given that the cost curves for green and blue hydrogen will fall in the way that so many expect, Bogers adds.

“There is an assumption that it will happen by default because of what happened with renewables,” he says. “But there are so many piece of the puzzle that need to come together in terms of infrastructure, R&D, and the regulatory framework.”

Only if the price is right

In the US, green hydrogen can be produced at roughly $5-6/kg, according to the Department of Energy(DOE). This would need to fall to $2/kg for hydrogen to be cost-competitive with other fuels, meaning the department is evaluating a wide variety of options.

“We hear a lot about grey versus green but we have another resources here than can provide low-cost hydrogen at scale,” says Sunita Satyapal, director of the DOE's Hydrogen and Fuel Cell Technologies Office.

“We have a couple of projects underway looking at nuclear-to-hydrogen. Nuclear can come in with low-cost baseload power where renewable generation is not there.”

The department has set up the Nuclear Hydrogen Initiative (NHI), which it says offers optimistic results for large-scale hydrogen production.

The NHI runs three separate projects using three different technologies. However all the projects are able to bring down the cost of green hydrogen production because they can perform high-temperature electrolysis, which uses less electricity.

97pc – Amount of hydrogen produced globally by methane reforming

Other ways to bring down the cost of green hydrogen is to situate production units in places where electricity costs are very low because of abundant renewable generation. Concentrated solar thermal projects are often cited as a viable technology in this field because they can provide a more sustained flow of power.

But hydrogen is much harder to transport than hydrocarbons, meaning any savings in cost gained with this method might be lost once the molecules are transported back to demand centres.

One solution is to convert hydrogen to ammonia for transportation. “But then you have the problem of how to crack it back into hydrogen,” says Bogers. Other options include the migration of carbon-intensive industries to areas of green hydrogen production.

Any such solutions, and the development of a hydrogen economy generally, will require careful co-ordination of domestic and international policy. “Only when we coordinate the planning of the whole system can we take advantage of the efficiencies,” says Ana Quelhas, managing director for hydrogen at EDP.

“We are seeing many countries and regions setting their own targets, but this is just the starting point,” she says.

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Author: Tom Young