Pauli Hiltunen, Miika Rämä
The increasing share of renewable energy in the power sector has led to increasingly volatile electricity prices in the Northern European power markets. The district heating systems in Finland will see a rapid expansion of heat pumps and electric boilers. Thermal energy storages enable flexible heat production, when it is cheap. Thermal energy storages can also help combined heat-and-power production by decoupling the electricity production from the heat demand. In this study, North European energy system model was used to study the impact of increasing heat storage and demand response capacity in Finland's highly electrified district heating systems on the electricity system flexibility. The results show that the impact of the additional heat storages on the annual production mix is only marginal with relative changes of less than 0.6%. The most significant impact was on the production of combined heat-and-power and electric boilers. The use of electric boilers increased especially in the climate year scenario of 2016, where the electricity production costs were highest. The increased flexibility can be seen in the terms of decreased ramping of hydropower and electricity imports. At the same time, the ramping of combined heat-and-power and electric boilers increased. Tank thermal energy storages contributed to this more. The use of demand response differed from the tank thermal energy storages as it was used more for short term adjustments of power demand with lower charging and discharging rates. In the end, the impact on the entire energy system remained small.