P2H-Pot - Potentials, economic feasibility and system solutions for Power-to-Heat

Heat pumps are an economic viable option in district heating networks already using geothermal energy under the condition, that the geothermal power or supply temperature are not sufficient. Even though a positive impact on the economy of P2H due to the reduction of taxes and fees for electricity can be seen, the results show that other conditions in the district heating network are more relevant. Especially the power of available cheap excess heat sources and the competition with potentials of direct usable excess heat, geothermal power and heat from waste incineration CHP plants. The taxes, network charges and fees are particularly relevant for the economic share of direct electric heating in district heating. Assuming current taxes and charges, electric heaters are not suitable for heat supply in the analyzed scenarios up to 2050 from an economic point of view. The simulation of the potential of P2H for balancing power was out of scope in this study. Present experiences show that electric boilers can be economic for providing balancing power. Heat pumps contribute to a reduction of the CO2-emissions in the district heating supply and to a reduction of fuel and resource consumption. Nevertheless, essential core for reduction of the CO2-emissions in the district heating sector is the efficiency increase in the building sector. In winter the heat pumps are mainly used for base load operation, whereas in transition periods and summer (April to September) they provide flexibility to the electricity demand. According to a recent PhD thesis (Rab, 2017) heat pumps contribute as part of a district heat generation portfolio to the risk hedging against long term price risks.

Results and Conclusions

The simulation results for the scenarios show the potential of major market shares for large heat pumps in the district heating supply assuming a high share of renewables and low CO2 emissions. The share of heat pumps in the district heating supply manly varies between 10 and 30 % in 2050, depending on the scenario. For most of the considered district heating networks, heat pumps are already economic viable in 2030. The considered sources of anergy in this study are flue gas condensation, low-temperature excess heat and geothermal energy. The results show, that heat pumps in combination with flue gas condensation are economic promising options for larger biomass-CHPs and biomass heat plants. Also a high share of CCGT allows heat pumps to cover up to 35 % of the supply. The limiting factor in all above mentioned cases is the amount of available anergy as heat source. For other analysed district heating networks (Kirchdorf, Braunau, district heat network type 2 – i.e. a large city with waste incineration, CCGT CHP, biomass CHP, industrial excess heat and additional excess heat potential) the demand supplied by heat pumps is limited by competing heat supply options: available excess heat potentials, geothermal energy or waste incineration CHP.