Small wind turbines for households and companies
Starting point / motivation
The negative experience of owners of small wind turbines animates us to analyze small wind turbines more detailed. A main problem is the range of wind speed of conventional small wind turbines. Conventional small wind turbines are designed for high wind speed, but under on-shore conditions the wind speed is low (<4 m) also because of low masts (<12 m).
Contents and Objectives
After finishing the analysis of different small wind turbine concepts (H-rotor, rotor with wind concentrators and wind diffusers, propeller-rotor with different generators and power converters) follows a continuous development of an optimal small wind turbine pilot system for low wind speed.
The main goal of the project is to develop small wind turbines for private houses and small firms especially in combination with heat pump systems regarding to the building regulations.
The systematic strategy to reach the project goal is geared to the complexity of a technical solution, the financial effort for realization and the aspiration to a high efficiency small wind turbine system. In several iterative steps within these boundary conditions the small wind turbine system should be successful in practical applications. Therefore every well developing step will be tested for several months.
Several experiences in practical operation of small wind turbines at low wind condition with low masts can be made.
The most efficient small wind turbine concept for low wind speed (<6 m/s) is the electronic rotation speed regulated two blade propeller rotor with a permanent magnetic cogging less synchronous generator. With an electronic rotor speed regulation system small wind turbines can be in operation at very high wind speed, but it is also possible to reduce the noise emission. In a perennial test phase could be shown that especially in the winter months the combination of small wind power and geothermal heat is a forward-looking technology, which complement one another. An expensive buffer for electricity is needless.
As a conclusion must be observed, that especially the local building regulations reduce the potential of small wind turbines dramatically and so at low wind conditions only a small part of electricity can directly produce at private houses and small firms.
Prospects / Suggestions for future research
At the time when the building regulation authority will admit that small wind turbine systems can be built a little bit higher than the existing buildings, then it will be possible to produce the electricity for private houses and small firms onsite. For generation of 4000 to 5000 kWh electricity for a single family house it is necessary to use small wind turbines with a rotor diameter between 5 and 10 m. Such amply dimensioned small wind turbines supply also at low wind speed the basic load of electric consumption without an energy buffer system. In which way the general public will accept and also use small wind turbines in the future depends on future costs of energy and on risks of non regenerative energy sources, which continuously destroy our environment.
DI Franz Zotlöterer