State of the art of windthermal turbines: A systematic scoping review of direct wind-to-heat conversion technologies

Abstract Windthermal turbines convert wind directly into thermal energy. Albeit it is an uncharted field of research, the overall system efficiency and costs of fully developed windthermal turbines are promising; since they can contribute to a sustainable energy transition. We identify the current state of the art of windthermal conversion principles, technology maturity, applications, substitutes, advantages and disadvantages. To scope relevant literature, we follow the Joanna Briggs Institutes selection and screening process resulting in 61 relevant publications from which we identified three main conversion types, namely compression-, friction-, and induction-based windthermal devices. These devices can directly supply thermal energy for space heating or industrial processes, work as a component of wind-powered thermal energy systems, short WTES, or can substitute any conventional or renewable heat device. Although heat is the lowest form of energy, windthermal applications could provide cheap renewable energy that can be stored easily enhancing security of supply. However, these technologies are currently on laboratory-scale, and we suggest scaling up the existing prototypes to engineering-scale. Finally, due to a missing general terminology, we propose to establish one of the terms windthermal energy, ventothermal energy or anemothermal energy to distinguish these specific wind energy conversion technologies.