UK study identifies platform reuse opportunities
Phase 2, which built on the findings and recommendations from Phase 1, focused on detailed definition of the technical concept. It involved engagement with engineering groups and technology vendors to design an efficient and safe hydrogen production system suited to harsh North Sea conditions.
Activities included identifying the Bosch ELY1250 PEM stack as the electrolyzer technology best suited to offshore integration, in terms of operating requirements such as controlled temperature and humidity. Veolia Westgarth then developed a customized Balance of Stack (BoS) design, which addressed gas/liquid separation, anode water treatment and electrolyzer cooling, and a Balance of Plant (BoP) systems, which included water treatment and hydrogen purification. The BoS design featured 12 x 41.5-MW arrays, each supporting 33 x 1.25-MW Bosch stacks.
Engineering the offshore hydrogen concept
For the primary electrical systems, Petrofac developed the system architecture, with 275/66/66-kV transformers, gas-insulated switchgear, shunt reactors, rectifiers and subsea cable reception. The system was devised to match hydrogen production to local offshore wind farm output (540 MW was deemed sufficient in the simulations). Recommendations for future design phases included a review of energy storage options such as batteries and surface hydrogen.
Apollo Engineering led the study into integration of the arrays, BoS/BoP and electrical systems into a topsides design optimized for North Sea conditions on a converted, existing offshore platform. Apollo consolidated the electrolyzers into larger arrays over three deck levels instead of four, also addressing hydrogen compression, flaring, HVAC systems for cooling of electrical equipment, and secondary electrical systems for platform operation. The Phase 2 team estimated the overall capex cost for such a project at £1.56 billion (US$2.09 billion).
Looking beyond first-generation projects
Phase 3, which concluded last April, examined potential scenarios going forward as technologies and markets evolve.
Five studies covered:
- Development of bipolar membranes and bipolar plates suited to direct seawater electrolysis and offshore-scale SeaStack systems;
- Marinization of electrolyzer technology for harsh offshore service, and capable of at least 10 months of autonomous operations with limited intervention;
- Anticipated and potential environmental impacts from normal operations and worst-case scenarios, including during commissioning/decommissioning;
- Requirements for digital technologies and methodologies, taking into account projected future advances; and
- Making offshore hydrogen production technically and economic attractive, and including societal benefits.
The conclusions from Phase 3 will be published later in the year.
German offshore hydrogen initiatives
In April, two consortia also made presentations at the NZTC’s headquarters on offshore hydrogen R&D projects in Germany, as part of a visiting delegation.
H2-Demo Global Tech:
H2-Demo Global Tech involves repurposing wind turbine bases for offshore hydrogen production, starting with a 10-MW demonstrator and eventually scaling up to 300 MW from a single production platform.
In time, this could be upscaled to 1 GW of installed capacity, powered by 20+ MW turbines. The presentation covered positioning of the demonstrator platform within an offshore wind farm in the German EEZ, adjacent to the 102-sq km SEN-1 area that has been designated for offshore green hydrogen production.
The presenters also examined the potential for using existing infrastructure, including wind turbine foundations, cables and SCADA systems; safety zone and sea surveillance requirements; power supply from the wind farm via the GT-1 offshore substation; and sharing of existing offshore operations and maintenance logistics such as CTV and technicians.
Other technical considerations discussed were desalination and electrolysis on a fixed turbine-foundation; testing of all components for production, storage and re-electrification; and exports via pipeline or ship transport.
The project partners are:
- Energiegewinnungsbereich, which is examining commercial and export elements;
- GRN.NRG.4.U, which is supporting the establishment of a hydrogen economy in the north of Germany;
- ONP, which has participated in the planning and enabling of various offshore wind farms in Germany, such as Merkur, Arcadis Ost 1, and HeDreiht;
- Rönner Group, which is leading development of the hydrogen platform with support from specialists at BVT, EnPro and Lloyd-Werft; and
- HF Offshore, providing maritime logistics.
Others involved in the development include ABB, Alfa Laval, Bosch, Draeger, RelyOn, University of Bremen, Technical University of Braunschweig.
AquaPrimus test platform:
The other presentation covered the AquaPrimus project, a planned nearshore demonstration site for testing offshore hydrogen technologies. According to the presenters, these are being held back by a shortage of real offshore test conditions for diverse technologies, processes, regulatory frameworks and standards.
AquaPrimus is developing a modular offshore platform for use in North Sea conditions, for R&D, certification and knowledge transfer. It will also support preparations for SEN-1 and other future designated offshore hydrogen production zones. The project will enable qualification of technologies for gigawatt-scale developments and deliver insights into certification, insurability and system design, reducing the risk of future large-scale projects.
Facilities will include a 2.5-MW electrolyzer (untreated H2), H2 processing up to 30 barg, 4.5 kg/hr for freshwater treatment, producing demineralized water at up to 6 cu m/hr; and integrated data collection and digital operations to address the needs for future interconnected energy systems.
