The remote German North Sea island of Heligoland has the ambition to become the centre of an offshore wind to hydrogen hub on a multi-gigawatt scale, as well as dedicated hydrogen pipelines to land.

As part of the AquaVentus vision, a first 30MW in electrolyser capacity (called AquaPrimus) is planned to be built by 2025 and connected with a hydrogen pipeline to Heligoland. Green electrolyser capacity on artificial islands fed by offshore wind close to Heligoland is then intended to grow to 5GW by 2030 and to 10GW by 2035, the initiative explains on its website.

"A year ago, the industry was very reluctant to build electrolysers into the sea,” Heligoland mayor Jörg Singer said, who spearheads the initiative.

"It was just like 20 years ago with offshore wind power. Then came the AlphaVentus pilot project 10 years ago. Today wind power is at sea with an installed capacity of approximately 6.5GW have become an integral part of the energy mix in Germany."

In less than 10 years, green hydrogen from the North Sea will be normal and at the same time an integral part of the national hydrogen strategy, the mayor of the island some 60 kilometres off the German coast added.

RWE supports H2 initiative

The AquaVentus initiative already can count on the interest of "renown" companies, Singer said, among the RWE.

“As the second biggest offshore wind operator in the world and biggest actor here on the island, we actively support the hydrogen initiatives around Heligoland,” Sven Utermöhlen, offshore wind chief at RWE Renewables, said.

RWE in a statement sent to Recharge stressed that is is operating its 295MW Nordsee Ost and the 302MW Amrumbank West offshore wind farms out of Heligoland. Next year, the utility will add the 342MW Kaskasi array (won by former unit Innogy in a 2018 tender) to that list.

As one of the partners in the AquaVentus initiative, RWE says it is bringing in competences that are key for the development of a strategic concept and a possible construction of projects.

The company has a small team that is working on advancing the Heligoland hydrogen idea, contributing RWE's expertise in offshore wind. The team is in contact with RWE colleagues in the Netherlands, the UK and elsewhere in Germany, who are already working on research projects for the production of green hydrogen.

Utermöhlen last week had met Singer on the island to discuss offshore wind hydrogen hybrid plants with Stefan Kaufmann, the hydrogen representative of Germany’s government.

The cabinet of German Chancellor Angela Merkel in June had approved a $10bn national hydrogen strategy that sets targets for the ramp-up of a massive production of green H2 produced from domestic renewable energy sources, as well as large-scale imports from the EU and beyond.

Hydrogen pipeline AquaDuctus

As part of AquaVentus, the initiative plans to drive forward the idea of a central offshore hydrogen backbone pipeline dubbed AquaDuctus, connecting all upcoming hydrogen projects in the German North Sea first to Heligoland, then from there onwards to the German coast, and later to a meshed North Sea hybrid grid.

“If produced offshore this hydrogen could be brought to shore by a single, central backbone pipeline. Depending on the outcome of a first feasibility study costs will most likely lie in a range of €135-345m,” the initiative claims, making it far cheaper than transmitting power from offshore wind farms to land via high-voltage direct current (HVDC) lines and then producing the hydrogen on land.

Green hydrogen produced directly at sea and then transported via pipeline to land would cost some €0.06-0.12 per kilogramme of hydrogen produced, AquaVentus estimates, compared to a cost of €0.54-0.71/Kg of H2 if the electrolysis process would only be carried out on land.

The AquaVentus initiative is not to be mixed up with the Aqua Ventus project for a floating wind unit off the US state of Maine, which Mitsubishi-owned Diamond Offshore Wind and RWE aim to bring online by 2023.

Five phases that start with AquaPrimus

The 30MW AquaPrimus hydrogen pilot plant is slated to produce 2,500 tons of green hydrogen per year by 2025. A the same time, the AquaPortus sub-project is planned to upgrade Heligoland's harbour as a service port for AquaVentus, with new infrastructure for research and energy.

In a second step until 2028, the hydrogen pipeline is slated to be extended further into the open sea towards a yet-to-be-built 290MW offshore wind-to-hydrogen project, which is expected to produce 20,000 tons of green hydrogen per year.

Phase 3 of the project is supposed to boost the offshore electrolyser capacity with two large new dedicated projects that are slated to be connected to the hydrogen pipeline until 2030, while at the same time the hydrogen pipeline will be extended from the island to the German mainland.

Phase 4 is planned to connect up to 10GW of offshore wind electrolyser capacity by 2035, and supply Northern German with green hydrogen via the pipeline.

Phase 5 foresees to link the AquaDuctus pipeline to a hydrogen grid across all of Germany, and potentially connect the AquaVentus plants to a meshed grid in the North Sea that also includes the giant Dogger Bank offshore wind development in the UK. Links to future hydrogen hubs in the Netherlands and Denmark are also part of the vision.

An innovation cluster including the German Hydrogen and Fuel Cell Federation, the Offshore Foundation and the municipality of Heligoland together with business and research actors will develop a strategy paper for the German government by 2022 on how to put the AquaVentus vision into practice.

UPDATE to add comment by Heligoland mayor, detail, background from RWE