Freiamt, located 20 km from Freiburg, Germany, is a cluster of five villages and about 5’000 inhabitants in the Black Forest. It embodies the German way of improving renewables energies, while promoting tourism to show that it’s possible to be self sufficient in energy living in a clean environment. This cluster has become a reference in Europe. The green villages produce 130% of its needs in electricity and sell all the production to the grid. Electricity is produced via different renewable electricity production units, namely biomass gas power plant, photovoltaic systems and wind turbines. No major company has any share in this venture; the local population have participated to a multiple co-owner scheme.
Wind power in Germany and in Baden-Württemberg
Wind power in Germany has strongly increased since 1999, growing from 5 GW to 32 GW installed. The country holds today the 3rd place in world wind power capacity. Moreover, it is commonly agreed that onshore wind power generation has the potential to supply 65% of the total consumption in Germany. This figure will hardly be reached, however one should keep in mind that the country is expected a full closure of its nuclear power plants by 2022. This sector, which is employing about 100’000 people, raised an investment of 2.9 billion euros in 2011 and generates 1.3 billion euros incomes.
In the Baden-Württemberg state, the total wind power installed capacity reaches 682 MW in 2012. In the Freiamt cluster, the local population itself owns the wind turbines. This citizen wind park investment scheme, called the “Bürgerwindparc”, allows 1093 shareholders to owe 5.7 MW. “It started when some Hamburg investors showed interest in setting up windmills in Freiamt. The villagers wanted no outsiders muscling into their land, so they decided to erect the windmills themselves. Within a month or two, they raised the down- payment of 1 million euro. The banks loaned them the rest of the 6 million euro required to install the wind turbines,” said Erhard Shulz, who escorts visitors to these windmills almost every day. “The turbines were a success from the first day.”
They invested in two 1.8 MW wind turbines in 2001 and in a 2.1 MW ten years later. Regarding the success of this enterprise, they expect to renew the experience with a 7.5 MW brand new wind turbine. At the moment, this park produces 11GWh/year over a total generation of 15,4 GWh/year. With the new wind turbine they would produce 17 GWh/year and would then be able to supply 20’000 persons.
Before building wind parks, a prospection of the location must be carried out to choose the best location for the windmills. Sensors and mapping are usually used. It must have sufficient wind, little turbulence, and be easily accessible for logistics purposes. Generally, the most difficult step in the development relates to convincing the neighbourhood. The most common reason brought by people against wind power generation is known as the NIMBY (Not In My Back Yard) issue. Indeed, the aesthetic and noise aspects are often discussed. However, new blade designs allow today a significant reduction of the noise induced.
Governmental incentives mechanism for renewable energies development
This renewable energies development is helped by a complex mechanism called the German renewable energy (EEG) act. This law consists in taxing a part of the electricity sold to the customer to finance the development of renewable energies. The main points are described as follows:
- Renewable energy producers get a steady feed-in tariff for 20 years. In Freiamt, they get 9,1 c€/kWh from wind power.
- The grid manager must buy each kWh produced by renewable energy plants, and then receives money from the EEG account to compensate the imposed high price
- Renewable energy is bought prior to dirty energy like coal or fuel based generation
- The feed in tariff is decreasing by 1,5% a year for on shore wind power to stimulate innovation.
In 2012 Germany government has increased the EEG tax from 3,6 to 5,3 ct€/kWh in order to balance the fast growth of renewables and to meet the European Union ambitious climate and energy package target for 2020.
REMINDER: How do wind turbines works
A wind turbine blade (1) is shaped like an airplane wing. The wind passes along both side of the wing and make it move: high pressure on the intrados side and low pressure on the extrados side make the propeller spin by the difference of pressure, the aerodynamic resultant.
To capture the most energy, the head of the wind turbine must always be lead toward the wind by a control loop. Wind turbines are so high because the higher up you go, the windier it is.
The energy from the spinning is transmitted directly via the rotor shaft (2) (in gearless wind turbine) and induced to the stator coils (3). This generator produces electricity.
The electricity is transported to an inverter in order to adapt its characteristics to the grid. Then a transformer (5) located at the bottom of the tower (4) increases the output voltage to avoid. This process allows reducing line losses during transportation of the electricity
|Model||Enercon 126/7500 (onshore)|
|Energy output||7.5 MW|
|Rotation speed||5 to 11 rpm|
|Rotor diameter||127 m|
|Hub Height||135 m|
|Max wind speed||34 m/s (120 km/h)|
|Miscellaneous||Gearless assembly, special storm device|