A novel Renewable Energy Storage System tailored for Offshore Applications

Project Information

FLASC HPES

Grant agreement ID: 101161553

DOI

10.3030/101161553

EC signature date 30 July 2024

Start date 1 January 2025

End date 31 December 2026

Funded under

• The European Innovation Council (EIC)

Total cost

€ 3 571 416,25

EU contribution

€ 2 499 991,38

Coordinated by

FLASC BV
Netherlands

Periodic Reporting for period 1 - FLASC HPES (A novel Renewable Energy Storage System tailored for Offshore Applications)

Reporting period: 2025-01-01 to 2025-12-31

Summary of the context and overall objectives of the project

Europe’s energy transition relies increasingly on large offshore renewable projects, yet the variability of wind and solar power creates growing challenges for grid stability, curtailment, and the efficient use of existing transmission capacity. Today, no commercially available long-duration energy storage solution is optimised for deployment in offshore environments, especially in the shallow to mid-depth waters where most new wind farms are being developed. This results in higher system costs, lost clean-energy output, and slower progress toward climate targets.

The project addresses this gap by developing and qualifying an innovative hydro-pneumatic energy storage system that can be co-located with offshore renewable generation. The solution stores energy by using pressurised seawater and compressed air and leverages the ocean as a natural thermal buffer, enabling high efficiency, scalability, and the use of widely available, non-critical materials. The main objective is to deliver a fully qualified system ready for integration into future commercial projects.

By combining advanced engineering, robust thermodynamic modelling, and a structured pathway to industrialisation, the project aims to reduce the cost and complexity of integrating offshore renewables into the energy system. The expected impact is significant: improving utilisation of offshore wind assets, reducing grid congestion, and enabling a more resilient, affordable and sustainable European energy infrastructure.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Since the start of the project, substantial progress has been made across system design, modelling, and the preparation for system qualification. The engineering team completed several rounds of modelling and design refinement. A suitable site was identified and secured for the physical building and testing of the pilot plant. Permits and compliance aspects are already in place. Suppliers are working on key components for delivery in Q1 2026.

In parallel, the control strategy has advanced from preliminary concepts to a detailed architecture. Core algorithms for energy management, safety procedures, and dynamic operational response have been developed and tested in simulation environments. The associated software framework, including data acquisition, supervisory control, and interfaces for future integration with offshore wind assets, has been defined and partially implemented.

Work has also progressed on the industrialisation pathway, including supply-chain mapping, component standardisation, and preparatory studies for the qualification testing campaign. Engagement with environmental experts and regulatory stakeholders has confirmed the feasibility of deploying the technology in line with existing offshore project practices.

Overall, the project remains on schedule and on budget, and the technical foundations are now in place for the full testing and measurement campaign planned for 2026.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project has already generated several advances beyond the state of the art in offshore energy storage. The thermodynamic modelling has validated performance assumptions for a system that can achieve high storage efficiency in shallow to mid-depth waters, an environment previously inaccessible to other offshore storage concepts. The refined pre-charge and thermal-management strategies represent an improvement over existing compressed-air or pumped-hydro systems.

The development of an implementable control strategy tailored to offshore applications, capable of fast dynamic response and compatibility with grid-service markets, further differentiates the technology from current land-based storage solutions. The software and digital-modelling tools created to support the design have also enabled early integration studies with prospective clients and wind-farm developers.

Engagement with these clients has highlighted a strong commercial pull, indicating that the solution could reduce system-level costs, increase renewable-energy utilisation, and support new offshore applications such as hydrogen production or island decarbonisation. For full market uptake, the next steps include this system-level qualification, continued engagement with regulators and certification bodies, and securing access to scale-up manufacturing and project finance.

Preparation activities at the Plant One site

Preparation activities at Hycom’s site (one of the suppliers)

Preparation activities at Hycom’s site (one of the suppliers)

Preparation activities at the Plant One site

Preparation activities at the Plant One site

Wiring of an electrical cabinet

Preparation activities at Hycom’s site (one of the suppliers)

Preparation activities at the Plant One site