Heat pumps optimal sizing and operation accounting for techno-economic and environmental aspects

Heat pumps are a great asset for decarbonizing the heating sector, which represents 14% of the CO2 emissions in Europe. In this article, we propose a methodology to formulate and solve a mixed-integer linear optimization problem to find the optimal sizing and operation of air-to-water heat pumps while accounting for the unbalanced grid constraints. The goal is to maximize heat pump economic and environmental benefits and ease their integration into the electricity grid. Novelties of the proposed optimization method compared to the literature include considering several buildings with their own thermal characteristics, formulating a bi-criteria objective function, and detailed modelling of the heat pump and the hydraulic circuit. We solve the optimization problem for a rural feeder located in Belgium. For the considered case study, we are able to integrate 100% of heat pumps while satisfying user thermal comfort and ensuring grid operational constraints. We achieve a 3.1-fold reduction in life-cycle CO2 emissions while increasing life-cycle costs by only 18% compared to gas boilers. Our proposed framework can be helpful to distribution system operators since it allows to mitigate heat pumps impact on the grid. Moreover, it can be useful to policymakers because it quantifies heat pumps decarbonization potential.