In a study commissioned by the Federal Environment Agency (UBA), the Fraunhofer IWES Institue  comes to the conclusion that theoretically 13.8% of Germany’s territory was suitable for onshore wind power production, exceeding by far the 60 GW capacity established by UBA  in 2010 to reach a 100% renewable energy mix in 2050. The study sees 1,190 GW installable capacity leading to 2,900 TWh/a.
The calculations are based on two types of wind power plants, a high-wind power turbine with a capacity of 3.4 MW and a low-wind turbine with a higher hub height and a greater rotor diameter (140 m vs. 100 m/ 114 m vs. 104 m), possessing a capacity of 3.2 MW. According to Fraunhofer IWES, these installations are capable of generating 2,400 full-load hours as opposed to 1,700 full-load hours for the existing wind turbines.
When determining potential capacity, the economic viability was not assessed. However, technical and ecologic restrictions were taken into account. Given the legal and regulatory requirements, a minimum distance of 600 m to residential housing would have to be observed. If one doubled the distance to 1,200 m, 3.4% of Germany’s territory could be used for onshore wind power, still more than enough, Fraunhofer IWES says.
While the study excluded settlement areas, national parks, nature protection areas, roads, water surfaces and airports from the potential territory, it was not possible to consider the protection of species in the simulation, UBA says, adding that additional limitations, e.g. due to a lack of public acceptance or economic viability of the project, had to be established in each individual case.
To reach 100% renewable energy supply, the expansion of onshore wind power was very important, UBA points out, arguing that onshore wind power was the second cheapest renewable energy source after hydro power. Today wind power plants were generating electricity for an average 8 ct/kWh, a little more than the generation costs for conventional power from coal and gas, UBA says. In 2012 roughly 23,000 onshore wind power plants with a capacity of 31,000 MW were installed.
The results of the study in favour of onshore should not be read as directed against other renewable energy sources, UBA president Jochen Flasbarth said. Despite the great potential for onshore wind power a combination with other sources like photovoltaics and offshore wind power was necessary and important. However, “until the middle of the century” one had to think about the necessary growth of offshore wind power, the press release states.
In April a study  commissioned by Agora Energiewende  concluded that German politicians had a broad scope for action designing policies for the regional distribution of renewables and could even save EUR 2 billion a year until 2023. This would require a faster expansion of onshore wind turbines and a slower expansion of offshore wind power, the authors said.
Onshore wind power expansion figures high on the agenda of most federal states to the extent that Federal Minister for the Environment Peter Altmaier called on them to cut back their plans in September 2012 . Lately, the Federal Association of the Energy and Water Industry (BDEW) has also called for a better coordination  of the renewable strategies of the federal states and the government.
Source: UBA 
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