This paper investigates the potential of a concept for the commercial utilization of surplus intermittent wind-generated electricity for municipal district heating based on the development of an electric-driven heat storage. The article is divided into three sections: 1. A review on energy storage systems; 2. Results and calculations after a market analysis based on electricity consumption statistics covering the years 2005-2013; and 3. Technology research and the development of an innovative thermal energy storage (TES) system. The review of energy storage systems introduces the basic principles and state-of-art technologies of TES. The market analysis describes the occurrence of excess wind power in Germany, particularly the emergence of failure work and negative electricity rates due to surplus wind power generation. Based on the review, an innovative concept for a prototype of a large-scale underwater sensible heat storage system, that is combined with a latent heat storage system, was developed. The trapezoidal prism-shaped storage system developed possesses a high efficiency factor of 0.98 due to its insulation, large volume, and high rate of energy conversion. Approximate calculations showed that the system would be capable of supplying about 40,000 people with hot water and energy for space heating, which is equivalent to the population of a medium-sized city. Alternatively, around 210,000 inhabitants could be supplied with hot water only. While the consumer´s costs for hot water generation and space heating would be lowered by approximately 20.0%-73.4%, the thermal energy storage would generate an estimated annual profit of 3.9 million Euros or more (excluding initial costs and maintenance costs).

Thermal energy storage; District heating; Surplus wind energy; Latent heat; Sensible heat; Underwater storage

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