Costs for offshore transmission -- The bill for Round 3

The bill for connecting up to 25 GW of wind in the UK's third round of offshore development could be as much as £10.4 billion, according to a report by National Grid and grid consultants Senergy Econnect. The study was commissioned by the Crown Estate, the state agency responsible for leasing offshore sites for development. It says that identifying potential onshore and offshore reinforcements is the first step towards the UK's goal of 25 GW of wind power capacity from the third round of site licensing.

The report looks at the costs of connecting offshore wind farms to the mainland grid in each of the Round 3 development zones identified by the Crown Estate. It finds that grid connection costs would average £403,000 for each megawatt. The highest costs -- £477,000/MW -- would be incurred by projects in the North Sea on the Dogger Bank and Hornsea, more than 100 kilometres off England's east coast. These two areas have the most potential in terms of wind power capacity, with over 12 GW resulting in a total connection cost of £5.9 billion.

While the offshore network accounts for around 90% of the total connection costs for Round 3 projects, the report notes that the onshore network will require significant reinforcement. It states that connections will be affected by environmental and permitting constraints.

Cable corridors

Following up on the report's recommendations, the Crown Estate says it will identify options for "cable corridors" for new offshore transmission lines, including interconnectors. And it will help create the conditions to encourage supply chain investment. Furthermore, the report calls for work to start on "no regret" onshore reinforcements ahead of connection applications.

Rob Hastings of the Crown Estate comments that grid connections will be the key to the success of Round 3. "Ensuring that developers and the supply chain are confident that the grid issues are being addressed will attract investment and contribute to the UK's energy security of supply, help meet the UK's renewables targets and create jobs across the UK," he says.