District Heating and Cooling with Thermal Storage – A Virtual Battery
Wind energy is becoming a dominant renewable source, providing energy for consumers of electricity, heating and cooling. Unfortunately, few consumers can use the energy directly as the wind blows. We need storage, to avoid loss of energy.
By Anders Dyrelund, Senior Market Manager, and Søren Møller Thomsen, Energy Planner, Ramboll, Denmark
Electric batteries can offer storage capacity, but storing electricity following the fluctuations of the wind is expensive. Fortunately, district heating and cooling (DH&C) systems, which use the wind-generated electricity, can transfer electricity to thermal energy and store it for later use in a cost-effective way. Furthermore, combined heat and power (CHP) plants can generate electricity as back-up for the wind. Seen from the wind turbine, the DH&C offers the same services as a battery. In new urban developments, DH&C is cheaper than individual heat pumps and chillers. In existing Danish district heating systems, large-scale solar heating has been a driver for large seasonal thermal heat storage pits (see Figure 1), which have excess storage capacity for the integration of fluctuating wind.
