Cross-Flow Small Scale Wind Turbines: An Overview of Technology Development and Applications

The vastness of windy areas in Iran provides many opportunities for harvesting energy from wind. Vertical axis turbines, mainly as a category of small-scale turbines, are attracting interest and being further developed every day. One of these types of turbines is the Cross-Flow wind turbine (CFWT), which is a quite suitable option for urban and home applications, though its low maximum power coefficient is yet a challenge that must be addressed by feasible methods. This article reviews studies in the field of design and improvement of CFWT by changing the geometric characteristics of the turbine or providing a way to direct the wind flow into the turbine rotor. After introducing the CFWT, the methods for directing wind flow into the turbine and their effect on the power coefficient and performance of the system are described. These methods are basically divided into seven categories of Guide nozzle, Casing, Guide vane, Deflector, Cowling, Omni-Directional Guide Vane (ODGV), and Zephyr. This study indicates that a big portion of the conducted research has been on the development of ODGV. Also, this turbine was analyzed for three cities of Ardabil, Babolsar, and Zahedan in Iran based on three types of systems (direct sale, on-grid, and on-grid with batteries). The results of this study show that the direct sale approach is the best option for the utilization of CFWT in Iran, and the payback period time of fewer than 10 years is achieved only by reducing the CAPEX of the setup by 10%-29%.