Offshore

Offshore

The German government has set a goal for itself: reduce greenhouse gas emissions by 80 percent below the level of 1990 by 2050. The growth of renewables is the main tool towards reaching that goal. The industry believes that Germany can get half of its power from renewables by 2020.

In addition to onshore wind power, offshore wind will take us a long way towards meeting that goal. The German government aims to set up 10 gigawatts of wind power off the German coast in the North Sea and Baltic by 2020, with that number rising to 25 gigawatts by 2030. These targets are ambitious. Great distances from the coast and great water depths pose special challenges for the construction of German offshore projects. Already, the offshore plans are several years behind schedule.

It is uncertain whether the German government will reach its goals. After all, offshore wind power still entails considerable financial and technical risks. The first offshore wind turbines in Germany were set up in 2010/11 at the alpha ventus test field, followed by the two commercial wind farms BARD 1 and Baltic 1.

Plans in the North Sea and the Baltic

After comprehensive reviews of the impact on ecosystems, the fishing sector, navigation, and the military, the German Maritime and Hydrography Agency approved more than 20 offshore wind farms in the North Sea and three in the Baltic. All of them are outside of the Exclusive Economic Zone (EEZ) of 12 nautical miles. The adjacent German state provides approval within that zone. At present, individual German states have approved four wind farms in the North Sea and two in the Baltic. Collectively, the 4,700 turbines have a capacity of 21,400 megawatts, an average of 4.5 megawatts per turbine. The 508 turbines approvedor the Baltic have a cumulative output of 2,368 megawatts, equivalent to 4.6 megawatts per turbine.

For the North Sea, 50 approval proceedings are also underway for a total of 5,700 turbines with a total capacity of 28 gigawatts in the EEZ. For the Baltic, nine new wind farms await approval. They would be worth 530 turbines and a total capacity of 2,300 megawatts. Most of the projects are at least 30 kilometers from the coast and therefore not visible from land.

How coastal regions benefit

At present, no fewer than 14 ports on the North Sea and the Baltic are revamping to meet the requirements of the offshore wind sector. They are adding additional space for turbine and component manufacturers, providing the load-bearing capacity on access roads for the transport of hundreds of tons of heavy foundations and system components, and building heavy-load terminals and docks for special industrial ships. In addition, shipyards and shipbuilders are also benefiting from these growth plans. Installation ships and platforms, ships that lay cables, and ships that transport giant turbines and staff are few and far between.
In addition, training centers are already being built for servicing, maintenance, and assembly, as are control centers, where highly specialized staff will remotely monitor wind farm operation. Finally, the sector is attracting numerous service providers – from helicopter services to operation & maintenance firms, logistics, and experts who monitor the planning, construction, and ramp-up of the maritime wind farms.

Offshore operation and maintenance

When offshore turbines fail, offshore wind farms lose a lot of money because multi-megawatt turbines would otherwise produce so much power. The situation worsens when bad weather delays repairs. Reliable turbines and clever operation and maintenance (O&M) concepts are therefore in great demand. Electronics for remote turbine monitoring and redundant systems are the standard; regular inspections and maintenance of foundations, rotor blades, and cable connections are indispensable. Experts estimate that O&M will make up around the fourth of the cost of offshore wind, with the turbine itself making up around third.

In comparison, the cost of the turbine makes up around two thirds of the overall cost on shore, with O&M coming in at only a few percentage points. In addition the cost, the offshore sector has to face the challenge of spare parts and staff logistics. When the seas are rough, service teams need several hours to arrive at a wind farm, and it is hard to get from the ship to the turbine. Helicopter transfers are faster, but also more expensive – and often not possible in fog or strong wind.

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Quelle: www.wind-energie.de/en/policy/offshore