DISTRICT HEATING: THE KEY TO UNLOCKING THE POWER GRID’S POTENTIAL TO RENEWABLE ENERGY
By John Flørning, Lead Energy Planner
Sebastian Wulff Holtegaard, Consultant
Søren Møller Thomsen, Senior Analyst
Electricity planning The district heating (DH) plants in Denmark have supported the electric grid for decades with services from the cogeneration (CHP) plants and, within the last decade, with services from heat pumps and electric boilers as well. In the continued build-out of renewable energy (RE), the consequent increase in intermittent production has led to more hours, necessitating the curtailing of RE. In response, an increasing amount of DH plants establish electric boilers to absorb the excess production, and to provide services to the grid. In 2023 it was publicly announced that Energinet will actively use electric boilers for balancing the very short-term fluctuations in the frequency. DH systems offer great potential for improving robustness and energy efficiency, reducing greenhouse gas emissions, and integrating renewable and waste heat sources. In addition to the benefits of DH compared to individual heating, flexible
DH systems can also support the power grid with balancing services by responding to price fluctuations and grid stability needs. Electricity planning On the power market, the marginal costing principle guides the dispatching of the plants, and as RE (wind, solar, hydro) has the lowest marginal costs, these technologies are planned in baseload operation. Depending on the actual required capacity, other and increasingly in-efficient power plants are dispatched with increasingly lower priority. Therefore, the hourly wholesale price of electricity is a good measure of the grid emission factor as the marginal units settle the power price. Due to the intermittent nature of wind and, in particular, large- scale solar PV production, it is necessary to install a much higher capacity than the required peak production in the power system. Hence, in the hours when the peaking capacity is needed, there are not necessarily adequately high wind
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