Hydrogen is undergoing an incredible change. It has joined the fight to decarbonise traditional industries while ensuring that its own future production is also carbon-free.

Hydrogen production of 70mn t/yr is mainly used as feedstock for fertilisers and refining, with less than 5pc of this supply considered free of carbon emissions. Green hydrogen could decarbonise these existing uses—and by doing so reduce global carbon emissions by 2.5pc.

300GW - EU target for offshore wind generation by 2050

But green hydrogen could also help with some hard-to-abate activities: transportation, industrial energy, heating buildings, power generation and steel production (through direct reduction of iron ore). These additional uses could lead to a dramatic rise in global hydrogen production—up to 550mn t/yr—in line with the Paris Agreement’s 2°C scenario.

Green production

In a year that many would like to quickly forget, green hydrogen has gained substantial political momentum. Germany and Norway released national hydrogen strategies in June. These countries were followed by the European Commission, which set an ambitious 6GW target for green hydrogen by 2030. France joined the movement by dedicating €7bn for clean hydrogen in its Covid-19 recovery plan. And there will soon be more countries to add to this list.

These goals, however, mean it will be necessary to scale up renewable energy. The latest EU strategy acknowledges the great potential of offshore wind and has set a target of 300GW by 2050.

Europe could import green hydrogen from regions with good solar and onshore wind resources. But whether in a compressed or liquid form or transformed into ammonia or hydrogenated oil, transportation would bring burdensome cost and efficiency losses.

Offshore wind

Local offshore wind power generation is an ideal fit for green hydrogen production as it is a scalable, reliable technology with higher capacity than other renewable energy sources. In addition, offshore locations are optimal for near-shore hydrogen consumption, such as coastal industrial facilities and shipping.

Reciprocally, green hydrogen can solve several challenges faced by offshore wind. Hydrogen production facilitates the integration of offshore wind into the energy mix. Faced with grid constraints, producing hydrogen limits power curtailment and the so-called ‘cannibalisation effect’ and protects the revenue of windfarm owners. It also offers long-term storage capabilities and new offtake opportunities, which are especially important for regions with growing offshore wind capacities.

And, perhaps most significantly, it unlocks the massive potential of far-from-shore windfarm sites. Large-scale electrolysis at sea, combined with transporting hydrogen via pipelines, eliminates the need for expensive electrical transmission cables.

Electrolyser locations

At first glance, it may seem logical to connect more offshore wind production to the electrical grid and then convert this electricity into hydrogen at the consumption site. This would mean the grid mix becomes greener and electrolysers could work on a stable baseload.

But does this really help the overall energy system? Grid-connected offshore wind requires expensive reinforcement of the onshore electrical network, and fossil fuel power plants could be needed to compensate for the intermittency of power input into electrolysers.

[Green hydrogen] unlocks the massive potential of far-from-shore windfarm sites

Producing green hydrogen at sea could be a valuable solution to these issues. There are two main designs under investigation:

A centralised solution. Offshore wind turbines would be connected to a substation at sea via electrical inter-array cables, just as is done today. But added to the offshore substation would be a large-scale electrolyser, a desalination plant with a seawater pump, and a compressor. The produced hydrogen could be then be transported to shore via a pipeline, replacing electrical converters and export cables.

A decentralised solution. Hydrogen would be produced at each individual turbine, with an electrolyser located in the tower or on its foundation. This design requires no electrical or sea platform infrastructure at all, avoiding the need for inter-array cables, an electrical substation and an export cable.

Is it feasible?

The first set of challenges are technical. Firstly, the ability of electrolysers to handle intermittent wind power, especially when connected directly to the turbine, instead of being centralised at the park level. Secondly, the electrolyser equipment must be able to withstand harsh offshore conditions. But while formidable, these challenges are certainly not dealbreakers.

The other challenges are economic but should improve over time. We can expect that electrolysis will benefit from the same steep cost decline experienced by renewable energy technologies. Technology costs will fall as hydrogen production grows—from less than 1GW/yr—and as innovation matures. In addition, offshore wind’s levellised cost of energy will continue to decrease with new generations of turbines coming to the market even in the short term. The ideal integration of hydrogen and wind power production will no doubt drive system efficiency, and maturation of the technology will naturally push down capital expenditure over time.

Green hydrogen has gained substantial political momentum

New industry

Germany is already looking at specific auctions for offshore wind and off-grid solutions. And Denmark is going to encourage over-deployment of windfarms, relative to offered grid capacity. Full value chain projects, connecting commercial scale windfarm production to large-scale industrial consumption, would be a way of lifting this budding new industry to the next level.

But let us not stop there. Why not produce green hydrogen offshore for use at sea, and unlock a whole new way of looking at the shipping industry? The possibilities are endless. One thing is certain—we will see a drastic change in the way we use and produce hydrogen within the next decade. 

By Aurelie Nasse, Head of Strategic Marketing, MHI Vestas Offshore Wind

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Author: Aurelie Nasse