Study on operational performance and multi-objective optimization of a solar-wind- heat storage coupled medium-depth ground source heat pump

The low-carbon transition of building energy systems is essential for achieving carbon neutrality in the construction sector. The long-term operational safety and environmental sustainability of Medium-Depth Ground Source Heat Pump are critically challenged by soil thermal imbalance. To enhance the penetration of renewable energy and reduce associated emissions, this study proposes a solar-wind-heat storage coupled medium-depth ground source heat pump system. A dynamic simulation model was developed in TRNSYS, and multi-objective optimization was performed using response surface methodology to respond dynamic load profiles of the targeted building. A comprehensive 3E (energy, economic, and environmental) assessment is conducted to assess the operative character and performance of the proposed system during the 20-year operation. The results indicate that this proposed system maintained stable soil temperature over the operational lifecycle, while the conventional medium-depth ground source heat pump system result in a 13.1% decline. Sensitivity analysis revealed that Photovoltaic thermal area, wind turbine number have the dominant influence on system performance. Multi-objective optimization identified the optimal configuration (1600 m 2 Photovoltaic thermal, 8 wind turbines, 152 m 3 heat storage tank, and 186 m 3 ·h -1 pump flow rate), yielding a minimum levelized cost of electricity of 0.085 $·(kWh) -1 , a carbon emission reduction of 1965 tons, and an annual net electricity generation of 404 MWh. Overall, the integration of solar, wind, and heat storage coupled medium-depth ground source heat pump can fundamentally mitigate soil thermal imbalance while enhancing energy efficiency and economic viability. This work provides a proven engineering blueprint for deploying safe, sustainable, and economically viable heating systems in cold regions, fundamentally turning a major process safety risk into a controllable design parameter.