Offshore: Plan for European offshore grid

Trade body releases infrastructure proposal.

A 20-year master plan for the development of a European offshore electricity grid has been proposed by the European Wind Energy Association (Ewea).

The association is urging the European Commission to incorporate the proposals in its blueprint for a North Sea grid, due to be published in 2010. Ewea's grid plan forms part of its Oceans of Opportunity report, which outlines offshore wind's potential for helping to meet EU renewables targets. According to the report, over 100 GW of offshore projects are already existing or planned - capable of meeting 10% of Europe's electricity while saving over 200 million tonnes of carbon emissions each year. This level of developer interest shows that Ewea's targets of 40 GW of offshore wind capacity by 2020 and 150 GW by 2030 are realistic and achievable, it says.

Fundamental to realising this level of deployment is a dedicated offshore grid. As well as connecting remote offshore wind farms, a pan-European network will smooth the variability of their output and improve Europe's ability to trade electricity across borders, increasing security of supply. Ewea points out that 2010 will be a key year for grid development. As well as the commission's blueprint for a North Sea grid, Europe's new association of electricity transmission system operators, ENTSO-E, is due to publish its first ten-year network development plan, which will take into account the need to connect increasing volumes of offshore renewables.

North Sea Links

Ewea's proposals for an offshore network for the next ten years build upon subsea interconnectors already existing and those planned by northern Europe's grid operators, amending them where necessary to connect offshore wind farms in the process. Eleven offshore grids are currently operating in the North Sea and Baltic Sea, with a further 21 offshore interconnectors currently being considered by transmission system operators (TSOs).

Ewea proposes adding nodes in the high-voltage direct current (HVDC) links between Norway, Germany and Denmark, and Norway and the UK, to hook up wind farms - particularly in the UK and German offshore wind concession areas, where the countries' governments have put forward sites for development.

On top of these amended TSO plans, Ewea proposes additional links to create an interconnected network by 2020. Increased links with Norway would allow northern Europe, with some 40 GW of variable offshore wind power by 2020, to benefit from siginificant amounts of controllable and storable Norwegian hydropower.

Looking further ahead to its target of 150 GW of offshore wind by 2030, Ewea proposes strengthening links between Ireland and the UK. Ireland would also be connected directly to France, while nodes off Belgium and the Netherlands would be linked to the German and UK nodes. Further north, Norway would be linked to Scotland via the Shetland Isles.

Most of the lines are expected to use the new HVDC voltage source convertor (VSC) technology which, with minimal transmission losses, is suited to the long distances involved. But more research and development is needed to bring the technology to the necessary maturity, says Ewea. So far, only two companies - Siemens and ABB - offer HVDC VSC, but other players are in the process of developing their own versions of the technology.

The report estimates that the 2030 offshore network would cost a minimum of EUR20-30 billion. This compares with the EUR187 billion estimated by the International Energy Agency (IEA) to be the total investment needed for European electricity grids for the period 2007-2030. But a transnational offshore network alongside increased onshore interconnection will bring economic benefits to Europe. Ewea's TradeWind study, published in March 2009, found that increased onshore network upgrades with several offshore interconnections would save a minimum of EUR1.5 billion a year in operating the transmission system.

Ewea's network plan will provide a truly pan-European electricity superhighway, says chief executive Christian Kjaer. "This will bring affordable electricity to consumers, reduce import dependence, cut carbon emissions and allow Europe to access its largest domestic energy source - offshore wind," he adds.