Distributed Grid Storage by Ordinary House Heating Variations: A Swiss Case Study

In Switzerland, the daily and annual profiles of electrical energy supply are deeply reshaped by the increasing importance of non-flexible renewable sources, i.e. solar and wind, slowly replacing nuclear power plants. Load shifting can be a special help, adapting consumption to this new production, allowing to develop and implement new storage solutions. In this paper, we present a solution that uses existing heating facilities of residential buildings to store electrical energy as thermal energy in buildings. Charging is performed by the margin power of heating systems, i.e. the difference between installed power and the heating power that is currently necessary. It is a storage solution limited to times when heating is necessary with charging/discharging powers depending on the weather conditions. However, it has the crucial advantage to be distributed over the grid and therefore adapts especially well to expanding non-flexible renewable distributed energy sources. Based on the Swiss Federal Statistical Office (FSO) buildings and dwellings statistics, this paper shows that in Switzerland, this solution could deliver a storage capacity above 6 GWh (for 1° change in room temperature) with peak charging/discharging powers at balance (i.e. when they are equal) of about 2.3 GW. The storage potential is hence in the same order of magnitude as large pump-storage hydroelectric power stations like Nant de Drance.