The value(s) of flexible heat pumps - Assessment of technical and economic conditions

Residential heat pumps are one of the most resource-efficient means for space heating, and their market shares are expected to rise substantially over the next few decades. Through installation of a thermal energy storage, the operation of a heat pump is to a certain extent decoupled from heat demand. Such flexibility is frequently claimed to bear a high potential for demand-side management. This study investigates the operational cost savings achievable through the use of such a flexibility option. To this end, a dynamic model of a coupled building and heating system is developed, and several economic model-predictive control strategies for heat pump operation are derived. These strategies exploit real-time prices and the flexibility of the thermal capacity of the building and/or heat storage. The proposed algorithms are applied using perfect and imperfect foresight. Furthermore, different variations of real-time prices along with several building and storage configurations are investigated. The resulting operational cost savings are contrasted with different paths of investment-cost developments. Results of this investigation demonstrate that investments in flexibility measures (smart-home equipment, thermal storage capacity, etc.) are, for the most part, economically unviable. However, it is also realized that economic feasibility depends greatly on the technical set-up and economic conditions. This study demonstrates that the potential of flexible heat-pump operation is frequently overstated. On the other hand, configurations for which overall system-cost savings could be deemed achievable are also identified.