Research project “Wind-powered heating 2.0: long-term storage”

Wind energy now accounts for the largest percentage of electricity generated by renewable energies in Germany. Especially during periods with high winds in winter, the German electricity grid provides an oversupply of electricity that results in very low or even negative prices on the electricity exchange. In some regions, wind farms must be throttled or even temporarily shut down completely to ensure grid stability. With their large thermal storage masses, buildings in Germany offer enormous potential for heat storage. Since wind power will play an important role in the electricity grid of the future and is available in excess - especially during periods with high winds in winter - the time coincides closely when highly efficient buildings need to be heated and when surplus power is available. In the future, buildings with wind-powered heating 2.0 will be able to meet their energy needs in an environmentally and system-compatible manner by generating heat from renewable surplus electricity. At the same time, they will be able to contribute to the successful implementation of the energy turnaround. For the electricity grid, system compatibility also results from the fact that buildings with wind-powered heating 2.0 can do without electricity for heating purposes during longer phases of high grid utilization (one to two weeks).

In the project "Wind-powered heating 2.0: long term storage", different storage technologies, high-temperature stone storage (HTSS), water storage and building components with integrated long term storage (BCS) are developed, which enable surplus wind power to be used to heat a building. To do this, the storage size must be adapted to the heating requirements of the high-efficiency building for one to two weeks, and appropriate charging and discharging control systems must be devised. To develop suitable solution strategies, extensive analyses are first carried out using building simulation software (WUFI® Plus). This is followed by measurements on prototypes at the Fraunhofer IBP outdoor test site in Holzkirchen, in twin houses (two identical single-family houses, HTSS and retrofitted with BCS) and a concrete CUBE (newly built with BCS) to validate the respective concepts. The various solutions developed are based on the criteria of economic efficiency, wind power coverage, user comfort and environmental impact - considered over the entire life cycle. To support the later market launch of the wind-powered heating 2.0 system, a planning tool for specialist planners will be provided.

Initial results from preliminary studies show that buildings with wind-powered heating 2.0 can reduce their primary energy consumption of non-renewable sources by 55 to 85 percent over their life cycle. These savings relate to a comparative building according to EnEV 2014 with reference technology, under assessment of the operating phase and taking into account the additional construction work required to achieve the wind-powered heating 2.0 standard.

Now that the storage systems have been successfully developed and installed, measurements are currently being conducted in the twin houses and on the concrete CUBE to verify the respective approaches, including the predictive control system, which calculates the heat demand for the coming weeks based on the weather forecast.

Following the research project at the end of 2021, there are plans to verify the various storage technologies in initial real demonstration buildings. A corresponding research proposal is currently being prepared and the search for suitable demonstration objects is underway.