The role of district heating in coupling of the future renewable energy sectors

Abstract

For the last decades energy efficiency initiatives have avoided enormous amounts of energy consumption, to the favor of the environment and consumer expenditures. Although there is still a big potential for further energy efficiency improvements it is time to move further and start preparing the whole energy system for the challenge of oversupply from intermittent renewable energy sources, particularly in the power sector. In 2015 the maximum one-hour power oversupply from wind turbines alone in Denmark happened the 26th of June, peaking at around 900 MW and the oversupply over a 15-hour period was 10 GWh. Known solutions to make use of oversupply in the power sector are power export, energy storage and halting the power generation. The power export needs to rely on sufficient capacity at local interconnectors, power demand in the importing country and there is an economic gain in the export. Energy storages can range from storing of power in batteries, pumped hydro, synthetic fuels to fuel displacing at other energy sectors. The last option is stopping the turbines, which should be avoided. The optimum energy storage would have large capacity, fast charging, high recovery efficiency and low cost. Scoring high on all criteria’s can be difficult when focusing on a single energy sector. By widening the perspective and start taking advantages of synergies between the energy sectors there is a possibility to score high on all three criteria’s. In this paper the potential of utilizing synergies between the power and heat sectors will be explored by considering the projections for the Danish energy system in 2025. The result of the analysis shows the optimum energy storage of renewable power is achieved through fuel displacement in the heating sector in combination with utility sized heat pumps, electric boilers and large thermal storages.