Power Production
Wind
Solar
Power Consumption
Electric Heating
Individual Heat Pump
DH Heat Pump
Winter
Summer
Figure 2: Seasonal distribution of production from wind and solar power compared to power consumption for heating based on electric heating, individual heat pump, and district heating partly based on a large, electrically driven heat pump (from Danish analysis).
The large heat pumps in district heating can use a wide range of different heat sources, which are unavailable for individual heat pumps. These include heat sources with higher efficiency delivering a stable temperature all year round – e.g., ground- water, geothermal energy, or surplus heat from industry. This means that the efficiency of the district heating heat pumps can also be high in winter. Energy efficiency is relevant both to the need for expanding renewable power production—for example, in the form of new offshore wind farms—and to the expansion of the power grid. Without focusing on energy efficiency—reducing energy con- sumption—the green transition will simply be too expensive for society. There is a difference in how much the various alternatives strain the power grid in winter. Electric heating and individual heat pumps, respectively, consume 7—and 3-times more electricity than district heating when compared to the monthly average consumption for February (Danish conditions).
In addition, individual solutions are less flexible, as electricity consumption directly follows the current outside temperature and does not allow for district heating for storage and alterna- tive heat production that is not based on electricity. Therefore, individual solutions can pressure the power system when it is cold, and the power production from wind and sun is low (e.g., windless winter weather). The seasonal differences between power production and pow- er consumption are also important. Fig. 2 shows numbers from the Danish example for the summer period (April-September) and the winter period (October-March). The results illustrate that district heating is also a better match for the seasonal wind and solar power production than electric heating and individual heat pumps. Significantly more electricity must, therefore be moved and stored if the electricity consumption is in individual homes rather than in large heat pumps in the district heating system where surplus heat production from the large heat pumps can
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