One of the main issues to be solved for the 21st century is the energy generation from renewable sources. In particular, wind energy has a large potential and is one of the most advanced technologies currently available. However, in many cases wind energy is restricted to large wind parks with wind power plants often reaching heights greater than 100 m. In areas with high population density such as cities, where many obstacles like buildings are present, the construction of large wind power plants is often problematic. In such areas, small wind power plants are an alternative due to their lower starting wind speeds and higher flexibility in terms of logistics, costs and space-demand. However, small wind power plants are mainly used on roof tops of buildings in European cities, if at all. The capital of Germany, Berlin, can serve as a typical example of this issue’s large wind power plants have been declared as unsuitable for the Berlin area. The present study attempts to contribute to small wind power site assessment in Berlin by performing a GIS-based overlay analysis for small wind power plants on free space and in addition on electric power poles, which can serve as supporting towers for small wind power plants. The focus of the GIS-based overlay analysis lies on a safety and performance point of view, including factors such as wind speed for three different power plant heights (10, 20 and 30 m), land use, distance to power line network, safety distance to buildings and wind shed/turbulences distance to buildings. The latter two depend on the regarded wind power plant height. Even though the overlay analysis technique and associated weight criteria (rank and ratio scale based weights) and decision rules (simple additive weighting) used in this study are chosen to be transparent and simple, they have been proven to be useful to investigate the influence of the included assessment factors on suitability.
As a result of the study, we show that up to 9% of the total area of Berlin is suitable for small wind power plants with a height ≥ 20 m. Interestingly, the suitable areas are very scattered throughout the Berlin's area. Furthermore, up to 28% of Berlin's power poles are suitable to serve as constructional bases for small wind power plant rotors. This result is a pointer for other communities to utilise power poles and other pole type structures, such as telephone poles, antennas, etc for the erection of small wind power plant rotors. Finally, the results of this study emphasise the flexibility and potential of unconventional, decentralized wind power generation in cities such as Berlin, especially when compared to large wind power plant farm installations.