Getting green hydrogen production into deep water: the Dolphyn project

19 February 2020

Initial engineering work has now been completed for the Dolphyn project, which plans to combine green hydrogen production with floating wind turbines.

ERM (Environmental Resources Management), working in conjunction with Tractebel and ODE (Offshore Design and Engineering), has completed the first phase of the Dolphyn project, the pre-FEED design for a 2 MW prototype offshore hydrogen production facility using floating offshore wind as the power source.

The floating facility, based on Principle Power’s WindFloat technology, will produce ‘green’ hydrogen at scale and is being funded as part of the UK government’s £20 m Hydrogen Supply Programme.

With the initial engineering work completed the project is now seeking further funding to move forward to the detailed design stage. The aim is to make a final investment decision on the 2 MW prototype facility by March 2021.

The development plan for the project has a target date of 2024 for start of operation of the 2 MW prototype facility. A 10 MW full scale pre-commercial facility is planned to follow three years later.

Figure 1 shows a conceptual scheme for deep water offshore production of hydrogen.

The Dolphyn prototype comprises a WindFloat floating platform with integrated wind turbine, PEM electrolysis and desalination facilities.

The project is seen as helping UK efforts to roll out hydrogen at scale by the 2030s – a crucial step towards the end of the country’s contribution to global warming and to achieving ‘net zero’ by 2050.

The use of floating turbines will enable the most favourable UK offshore wind resources to be accessed, in deep water at distances from land of up to several hundred kilometres.

Dolphyn is a completely scalable technology that once established could be expanded across the North Sea (Figure 2).

A single 10 MW turbine could be used to produce in excess of 800 t of hydrogen per year, it is estimated.

The Dolphyn system is being designed such that it can be deployed in stand-alone mode or as multiple connected units to form an offshore hydrogen wind farm.

A 400 turbine ‘farm’ (20 x 20 array consisting of 10 MW turbines), with an installed capacity of 4 GW, could produce over 320 000 t of hydrogen per year.

The plan is to export hydrogen to shore via a pipeline, without any external power source being required.

The design has been developed through a detailed technical and financial evaluation process to achieve the lowest predicted cost for producing hydrogen from renewables at scale in the UK.

The ERM Dolphyn concept selected – modified WindFloat semi-submersible base on which turbine is mounted, together with desalination and electrolysis equipment, with the hydrogen exported via pipeline to shore – has been compared with other concepts (Figure 3): spar buoy with hydrogen pipeline to shore (Dolphyn single spar option); desalination and electrolysis on separate offshore platform, with hydrogen pipeline to shore; and export of electricity generated by floating offshore wind to land based electrolysers.

The Dolphyn semi-submersible option turned out to be the best in terms of estimated cost of hydrogen production, see Figure 4.

The future development plan is summarised in the table opposite.

As already noted, the Dolphyn offshore hydrogen production concept employs a modified version of the WindFloat semi- submersible base. One attraction of WindFloat is that it already has a suitable deck on which to place the hydrogen production equipment.

Also, among floating wind concepts, it is already quite well advanced, a recent milestone being the start of power export, on 31 December 2019, from the first of WindFloat Atlantic’s three platforms, located off the coast of Portugal (see photographs).

Each platform of WindFloat Atlantic is equipped with an MHI Vestas V164-8.4 MW offshore wind turbine. The Dolphyn development plan currently envisages use of 10 MW offshore wind turbines, but larger units are now being considered, which should result in cheaper hydrogen.

Figure 3. Offshore hydrogen production concepts compared
WindFloat Atlantic
Figure 4. Hydrogen cost estimates for the various concepts
WindFloat Atlantic
Figure 1. Conceptual scheme for deep water offshore hydrogen production
Figure 2. North Sea development potential
WindFloat Atlantic

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