German transmission system operator Tennet has warned that offshore wind commissioning is lagging behind transmission cable readiness. 'Cable-idling' could cost up to €1bn a year, it claims.
A study for Tennet by Offshore Management Resources has found that by 2023 only 3.7-5.9GW of offshore wind capacity will be built in the North Sea. Yet 11 offshore transmission cable systems with a total 6.2GW are currently under development or being built. Another two systems with 1.8GW are up for tender.
"We are building connection capacity ahead of time," said Lex Hartmann, Tennet executive board member. "We want to cooperate with the politicians and the offshore sector to define measures to secure optimal use of the contracted grid connection capacity."
Tennet's 8GW of cable developments is in line with the German Offshore Network Development Plan, which foresees 12.8GW of offshore transmission capacity by 2023. But the study identifies only 2.9GW of offshore capacity with financing in place, of which 2.3GW is being built.
This represents a turnaround for Tennet. Wind farm developers have been complaining about grid connection delays for German offshore projects. Complaints by Dong Energy prompted energy regulator Bundesnetzagentur to launch a formal investigation in January.