Thermal Energy Storage in Sweden and Denmark: Potentials for Technology Transfer

Management of intermittent renewable energy sources (RES) such as wind and solar is a significant issue for countries with interconnected electricity markets. Increasing amounts of electricity from intermittent RES increases the variability of electricity supply, causing electricity prices to become highly sensitive weather conditions. Unpredictable prices have a negative effect on new infrastructure investment both for renewables and for existing combined heat and power (CHP) production. Storage of electricity to alleviate that variability is costly and problematic. Storage of heat, however, is possible, and electricity can be efficiently turned into heat. Where there is a demand for district heating, Thermal Energy Storage (TES) can offer CHP /district heating operators the flexibility to produce heat from fuels, or with stored heat generated from ‘excess’ intermittent electricity. TES systems have evolved in different jurisdictions; if TES systems are to become mainstream, greater use of both existing technologies and applicable ones from other jurisdictions is necessary. Ensuring public understanding and acceptance of new ways of using electricity for heating (via heat pumps) is critical. Sweden and Denmark have developed independent strategies for TES: Aquifer and Borehole TES in Sweden, and Pit TES in Denmark. This paper identifies the path-dependent evolution of the Swedish and Danish energy systems that influenced the TES technologies that each developed. Opportunities for TES technology transfer between these countries and potential roles for government, businesses and regional planners are explored.