Denmark’s Bornholm Energy Island scheme was awarded just over half (52%) of the European Commission’s (EC) latest Connecting Europe Facility (CEF) funding round. The EC’s largest CEF round to date, nearly €1.25bn in grants were allocated to support 41 cross-border energy infrastructure projects, including three wind energy-related projects.

The Bornholm project is being developed by grid operators 50Hertz and Energinet. It is reported to be the world’s first hybrid direct current interconnector. Connecting to a 3 GW offshore wind farm in the Baltic Sea, south of Bornholm, the project includes a power hub on the island of Bornholm with two converters, direct current connections to the Danish and German mainland, and additional converter systems there for converting direct current into alternating current.

However, Bornholm partners point out that they are waiting for ‘regulatory clarity’ from Germany and Denmark before they can sign contracts for converters, transformers and other substation technology.

CEF grants were awarded to two other wind projects: Triton Link (€22mn), an offshore hybrid interconnector between Denmark and Belgium; and an offshore wind connection in South Brittany, France (€22mn).

‘These [three schemes] are key projects to deliver affordable electricity for European companies and households. So far Europe only has one hybrid offshore wind farm. We need many more to build an integrated offshore grid,’ says Vasiliki Klonari, Director of Energy System Integration at WindEurope.

Offshore hybrids are interconnectors between two or more countries which are directly connected to offshore wind farms. Combining generation and cross border transmission, they transmit electricity to all the interconnected countries and optimise energy flows. ‘Connecting wind farms directly to an interconnector reduces the need for cable connections and ultimately improves the use of maritime space. That reduces the impact on environment and maritime biodiversity,’ explains the trade association.

‘Offshore hybrids are key projects on the way to an integrated offshore grid. According to the European Offshore Network Development Plans, 14% of all offshore renewables could be connected via offshore hybrids,’ it adds.

WindEurope warns that Europe needs to invest more in interconnectors and cross-border electricity infrastructure to ensure the region’s electricity networks support the transition to a more electrified economy. ‘Without greater investment in grid infrastructure, Europe risks falling short of its clean energy ambitions. Grids are already the number one bottleneck to the expansion of wind energy in Europe today,’ it states.

‘In this context it is disappointing that the CEF round awarded only three smart electricity grid projects. They received less than 4% of the total budget [€47mn]. Meanwhile, hydrogen [€238mn, 19 projects], ammonia [€20mn, two projects] and CO₂ projects [€246mn, 11 projects] secured around 40% of the budget,’ the trade association continues. ‘Without stronger EU support for grid infrastructure, integrating renewables, boosting electrification, and ensuring affordable electricity for consumers and industries will be a challenge.’

WindEurope points out that the EU Action Plan for Grids foresees an investment need of €584bn of investment in electricity grids by 2030. The CEF is only funding cross-border projects. The trade association says that the biggest investments are required to optimise and expand the national electricity grids. ‘Here the EU, including the European Investment Bank, and the member states need to come up with additional funding tools,’ it concludes.

It should be noted that the latest EC CEF allocation round was the first one to include offshore electricity grids, hydrogen and CO₂ networks.

The remaining €7mn of grants went to two hydro projects.

OESTER project to advance offshore electricity storage
Meanwhile, 16 partners* from across the European offshore renewable energy sector have joined forces in project OESTER (Offshore Electricity Storage Technology Research), which aims to accelerate the development of offshore electricity storage technologies within the offshore wind sector.

As renewable energy systems expand, they face challenges like grid congestion and system instability caused by the mismatch between variable energy production and demand. These issues often result in electricity curtailment. In addition, simultaneous electricity production from multiple wind farms can lead to oversupply, causing electricity prices to plummet which significantly impacts the business case of offshore wind farms. Energy storage systems could offer a viable solution to these challenges, say the OESTER partners.

The three-year initiative’s ultimate goal is ‘to deliver scalable innovative offshore electricity storage solutions that can be applied across global markets, supporting the rapid deployment of renewable energy systems’.

Key technologies under evaluation include:

• Short-term storage: batteries integrated into wind turbine monopiles (Verlume).
• Medium-term storage: compressed air energy storage (Flasc) and underground pumped hydro storage (Ocean Grazer) co-located within wind farms.
• Long-term storage: electrolyser system installed on offshore platforms directly connected to wind farms (Battolyser).

Preliminary front-end engineering designs (FEED) and prototype components are to be developed to validate these hybrid systems. Digital twins will be employed to simulate system performance and optimise grid operations at gigawatt scale.

*OESTER comprises: wind developers and operators – RWE, Vattenfall, APG, SSE; storage technology developers – Verlume, Flasc, Battolyser Systems and Ocean Grazer; companies supporting offshore renewable energy and storage – DMEC and SeaWay7; research and knowledge institutes supporting ecology and digital twins of the system – Deltares and University of Groningen, and TNO (project coordinator); legal company NewGround Law and the Dutch storage association Energy Storage NL.