A successful energy transition depends on storage options in order to ensure power supply stability under a fluctuating generation of a growing share of renewable energies (RE). Battery storage is expensive and raw material intensive and therefore not suitable as a sole solution. Surplus electricity may easily be converted to heat, which can be stored inexpensively for a short term. With such simple Power-to-Heat or P2H solutions, lack of electric power cannot be offset by conventional heat storage. However, if a building or an urban quarter is heated by means of cogeneration, so-called Combined Heat and Power (CHP), or heat pumps (HP), the operation can be adjusted in such a way, that the building itself, i.e. its massive structure, serves as heat storage. Electricity generation and consumption is adjusted to the requirements of the grid (reactive power control). For the supply of a Berlin quarter, built in the 1950s and equipped with a district heating network and a CHP plant, the feasibility of the concept could be proved using dynamic building simulation as the analysis tool. Sixteen percent of the total heating consumption may useably be stored and extracted from the building structure. In absolute numbers: 73 MWh/a heat can be buffered corresponding to 34 MWh/a balancing electricity. For each square meter of living area, 3.7 kWh electrical balancing energy can be buffered in the building's thermal storage capacity. Nothing else is required than a re-programming of heating and possibly cooling controls. No capital investment is needed. Well insulated and more massive structures could show a proportion of 27% of such shifted heat.

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Author notes

1. PhD, Professor for Renewable Energies at HTW Berlin University of Applied Sciences, Wilhelminenhofstr. 75A, D-12459 Berlin, Germany, phone +49 30 50 19 3658, fax +49 30 50 19 21 15, email: [email protected]

2. B.Sc., consulting engineer, HTW Berlin University of Applied Sciences, Wilhelminenhofstr. 75A, D-12459 Berlin, Germany, email: [email protected]