Quantitative sustainability evaluations of hybrid combined cooling, heating, and power schemes integrated with solar technologies

Highlights: • A quantitative sustainability evaluation model of hybrid system was developed. • Five combined cooling, heating and power schemes were evaluated and compared. • Expert opinion and objective data were combined to obtain weight of criteria. • An index was defined to obtain penalty cost of environmental and social impacts. • Impact cost accounts for at least 13.2% of the total cost in the five schemes. This paper proposes a novel quantitative sustainability evaluation model of hybrid natural gas combined cooling, heating and power (CCHP) systems integrated with solar technologies, including sustainability indicator selection, normalization, weighting, aggregation, application, and sensitivity analysis. Three hybrid CCHP schemes respectively integrated with stationary and concentrating solar heat collectors and photovoltaic/thermal collectors and two natural gas CCHP schemes are configured and compared. Eleven indicators considering resources, technology, economics, environment and society were selected to estimate a composite sustainability index (CSI) for each of the five CCHP schemes. The "combined weighting" method was employed to define the indicators' weights, which combines subjective opinion of experts in the analytic hierarchy process method and the objective information of quantitative data in the information entropy method. The aggregated CSI provides a unique value for indicating the sustainability degree of schemes that is proportional to it. The results for a defined specific case demonstrate that the hybrid system integrated with stationary evacuated tube collectors has the largest CSI (0.868) and that the CSI of natural gas CCHP system, 0.756, is declined to 0.753 because of integrating the concentrating PV/T collector. The CSI provides a quantitative method to calculate the penalty cost of a scheme's negative environmental and social impact according to the economic cost of energy products, in which the dimensionless impact adjustment factor represents the magnitude of environmental and social impact. When the impact adjustment factor is set to 1.0, the lowest penalty cost of hybrid schemes accounts for 13.2% of total cost of energy product. The sensitivity analysis of indicator weights demonstrated the reliability of final evaluation results of the proposed quantitative sustainability evaluation model for hybrid CCHP schemes, and the comparisons with the conventional techno-economic model validated the proposed model.