Nano-enhanced thermal energy storage coupled to a hybrid renewable system for a high-rise zero emission building

Renewable energy sources suffer from intermittent availability. Adding a latent heat thermal energy storage (TES) is often proposed as an efficient solution to address their stability. In this study, a hybrid renewable energy system consisting of solar photovoltaic panels, evacuated tube collectors, and a ground source heat pump (GSHP) is investigated. The system was coupled with an underground nano-enhanced TES system for improved performance to meet the energy demand of a high-rise residential building in Toronto, Canada. The applied energy storage system in this study consists of nano-enhanced phase change material pipes buried vertically underground to address the temperature stability of the ground. To investigate the effectiveness of this hybrid renewable energy system, a novel co-simulation methodology is adopted. The efficiency of this system is analysed on the component-scale using CFD simulations. The results show that adding nanoparticles increases the thermal storage capacity of the GSHP by 26.4 %. Then the impact of the hybrid renewable energy system with improved storage capacity on the building scale was assessed using TRNSYS. The economic, environmental, and energy consumption impacts of the proposed system was evaluated. Without TES, 296 borehole heat exchangers with a depth of 243 m would be needed to meet the heat and cooling demand; however, considering the modified ground source heat pump, the number of boreholes were reduced to 197 with a depth of 163 m. The results showed a significant impact on the drilling cost reduction, and the life span increase of the geo-exchange system. The coefficient of performance of the final system increases by 27.1 %, while the building energy consumption decreases by 36.7 %.