Author:


Aaron Forster

    The Future of Energy: Episode 2: Wind Energy at sea

    While wind power onshore faces increasing resistance, potentials for offshore power generation seem unlimited. At which costs can power be produced on the high seas, and to what extent does it collide with shipping, fishing, marine operations and the conservation of nature? This is the focus of the second article in our series “The future of energy”.

    Wind Energy at Sea – Crucial for the Energy Transition?

    An overview of the costs and benefits of offshore wind energy

    Wind power is one of the main pillars of the energy transition in Germany. However, especially on land, the industry is struggling with fierce competition for suitable areas, high investment costs, caps on expansion set by politics, environmental issues, and the construction of connecting infrastructure. No wonder, therefore, that the focus has shifted to offshore wind power. A major advantage of offshore wind power is the relatively low fluctuation in the amount of wind and thus the consistently high amount of generated electricity. In addition, the costly plants – such as the wind farms alphaventus and Riffgat, both off the island of Borkum in the North Sea – are becoming cheaper, better and more profitable every year.

    Germany`s ambitious climate targets require a drastic expansion of renewable energy, with offshore wind power playing an important role in this shift. However, this expansion will not be free of conflict. The power and profitability of a wind turbine at sea depends on many factors. The further away from the shore it is, the stronger and steadier the wind it can harness. This means significantly higher and, above all, more consistent generation of electricity compared to similar plants on land. However, offshore plants entail higher costs for installation, connection to the grid, and maintenance. In addition, the individual parts of a plant must be protected against the penetration of salty sea air and water. The result are high investment costs.

    In order to increase productivity, ever larger turbines are being built. The assembly of a turbine accounts for a large share of its costs, which rise only slightly with larger turbines. Such turbines increase output considerably due to their larger surface area. However, larger turbines require greater distances between turbines, since turbulences caused by a turbine will otherwise reduce the output of adjacent turbines. This is a major problem in planning wind farms.

    Competition for space on the high seas

    And what about the space available for offshore plants? Is it virtually unlimited in the vast ocean? Germany builds its offshore turbines primarily in the Exclusive Economic Zone (EEZ). This is the zone between 12 and 200 nautical miles off the German mainland where the state has exclusive economic rights of use. The problem is that more and more sectors are competing for the limited areas in the EEZ. Fishing, shipping, raw-materials extraction, environmental protection, the military and research all compete with wind power on the high seas. The result is a complex clash of interests.

    The marine development plan issued by the federal government specifies which areas in the EEZ may be used and how. International and European agreements must also be taken into account. The latest development plan for the EEZ, which recently came into force, creates more priority areas for wind power, but often with various provisos.

    By 2040, offshore capacity is bound to increase up to 40 GW by means of the Wind Energy at Sea Act. Since the 2017 reform of the Renewable Energy Act (Erneuerbare-Energien-Gesetz or EEG in short), the right to build wind farms is awarded through public tender. This process is intended to reduce the costs for the expansion of wind energy through competition and to simplify planning. However, in the eyes of the offshore industry this mechanism curbs the building of new wind farms by effectively capping their expansion. This poses additional challenges for operators and investors.

    At the same time, technology is advancing rapidly, and some projects that do not receive any subsidies succeeded in the 2017 tenders. A study by the consulting companies Prognos and Fichtner (2013) assumes that the total production costs per kilowatt/hour will fall by about one-third by 2023 – more expensive than solar power, but cheaper than gas and coal.

    Enter the critics

    Critics of offshore wind energy comprise primarily environmentalists, who argue that the construction of the plants causes environmental damage. Noise from the construction, for example, can severely harm the sense of hearing and orientation in porpoises. Sometimes the turbines hit birds. Disturbances caused by the electromagnetic fields from the cables and the leakage of small amounts of toxic substances due to corrosion are possible. Yet once in operation, the turbines’ effects on the environment are less detrimental than those of many other types of power generation. The foundations for new plants and the gravel piled on top of these foundations can serve as artificial reefs for some species (such as lobsters and mussels). In addition, fishing is not allowed near the turbines, which preserves stocks. Offshore wind turbines have an operating life of 20 to 25 years. As the technology is still rather new, the industry has little experience with the dismantling of turbines at sea.

    The industry is looking for further efficiency gains in devising new processes, such as the coupling of turbines with wave power plants, floating wind farms and the production of green hydrogen directly in the parks. The federal government recently issued a draft directive to test the possibilities and potentials of producing hydrogen at sea. It will be a difficult task for politicians in the coming parliamentary term to balance the interests of the various stakeholders in the North and Baltic Seas.


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