Exergo-environmental cost optimization of a solar-based cooling and heating system considering equivalent emissions of life-cycle chain

Solar-driven energy systems can effectively reduce the fossil fuel use and pollutant emissions in the built environment. A solar-based cooling and heating (SCH) system employing solar thermal collectors, photovoltaics, a double-effect absorption heat pump, and an electric boiler/chiller is proposed to meet the energy demand of a community. The system and its components are optimized by simultaneously minimizing the specific exergo-environmental cooling/heating costs over the life-cycle and maximizing the cost saving ratio. Compared to the conventional exergo-economic and exergo-environmental optimization methods without life-cycle equivalent emissions, the results show that the system resulting from the proposed method has higher specific costs, or, 1.10 $/kWh for cooling and 2.77 $/kWh for heating, and the corresponding cost saving ratio is >0.02%-unit lower. The coefficient of performance of the hybrid system in the cooling and heating modes are 4.5 and 1.04, respectively. The specific heating cost shows the highest sensitivity against parameter changes. Increasing the capacity of the heat storage and price of grid power would increase the cost saving benefit, while increasing other parameters such as investment cost would decrease the saving ratio.