Vertical vs. Horizontal Axis Small-Scale Wind Turbines Serving a Typical House in Italy and Norway: Numerical Energy, Environmental and Economic Assessments

The performance of three commercial small-scale wind turbines (SWTs) serving a typical house have been analyzed via the software TRNSYS upon varying the climatic conditions of 5 Italian and 3 Norwegian cities. A Savonius vertical axis SWT (power output of 2100 W at 12 m/s and rotor swept area equal to 1.60 m2) has been compared with two horizontal axis SWTs, the first one characterized by the same power output at 12 m/s (but 3.8 times larger rotor swept area) and the second one with almost equal rotor swept area (but 6.8 times lower power output at 12 m/s). The selected SWTs have been compared with a baseline scenario where the same building is served by the central electric grid only from energy, environmental and economic points of view. The simulations highlighted that the vertical axis SWT produces 1.05÷11.54 times larger annual electric energy than the horizontal axis SWTs. The data also underlined that, with respect to the baseline scenario, the selected SWTs reduce annual electric energy imported from grid (up to 37.5%), the equivalent global CO2 emissions (up to 37.8%) and the operating costs (up to 112%), with a minimum simple payback period of 2.8 years.