Direct wind-to-heat energy systems integrated with storage for electricity and heat generation

The focus of this research is a techno-economic assessment of a wind-powered thermal energy system (WTES), which directly converts wind power into heat at the generation site and stores this heat in thermal energy storage for later use. Compared to conventional systems that convert wind to electricity, WTES can be a cost-effective solution for producing heat from wind power due to its minimal energy conversion steps. Two challenges in the development of WTES are investigated in this work. Firstly, the technology that converts the kinetic energy from wind turbine rotors into heat has not been thoroughly investigated yet. Several studies have investigated the wind-driven heater for water heating but not for high-temperature heat generation, which enables a wider range of applications. Secondly, the role of WTES in the future energy system is unexplored. A few studies have estimated the energy costs of WTES for electricity and heat generation, but generation and demand profiles and required storage systems have not been considered. In this research, eddy current heaters are selected to be investigated for wind-to-heat conversion due to their potential for high-temperature heat generation at low rotational speeds. The key design parameters and technical challenges of this technology were analysed, and a proof-of-concept device was designed and constructed for parametric study. The role of WTES for electricity and heat generation was investigated by operational simulations with wind power and system output profiles being taken into account. The energy cost of WTES was evaluated and compared with the cost of the systems that can provide similar services, such as electricity-generating wind turbines integrated with electrical or thermal energy storage. The analysis suggests that, for electricity generation, WTES has a cost advantage when a high fraction (e.g. 73–94%) of wind power is to charge storage, but the simulation results for different scenarios show that this fraction for WTES is not over 70%. Furthermore, the capital costs and conversion efficiency of different components for wind-to-heat conversion are reviewed and analysed. The results show that the energy cost of WTES for heat generation could be lower than other wind-to-heat conversion routes (e.g. electrical heating or hydrogen heating). However, converting wind power to heat at the generation site limits the use of wind energy in other sectors or energy networks. This study is the first comprehensive assessment of WTES in different aspects and can be the foundation of future research