Advancements of wind energy conversion systems for low-wind urban environments: A review

The past decade has witnessed rapid research and developments in wind energy conversion systems and related enabling technologies. The incorporation of wind turbines in the integral design of buildings has become a promising approach to promote on-site renewable energy conversion in urban areas. However, information pertaining the efficiency of the wind turbines, wind speeds and the integration of generated wind power to the grid in urban environments is scarce. This review paper aims to capture the fact that recent advancements in wind energy systems are able to deliver tangible benefits to the renewable energy technology (RET) industry as a whole. A comprehensive review has been carried out on the applied techniques of radial wind turbine (RWTs), contra-rotating wind turbines (CRWTs), hybrid Savonius–Darrieus rotor, piezoelectric generators, flag-type triboelectric nanogenerator and stretching-enhanced triboelectric nanogenerator. This paper provides a knowledge platform for readers to explore possible methods in exploiting the advantages of urban wind profiles with minimal vibration, noise and installation space. Unique approaches pertaining the developments of wind energy system in urban environments are reviewed and reported in this paper. Several research gaps are also identified to guide future study in urban wind energy conversion systems.