Environmental and energy assessment of a small-scale solar Organic Rankine Cycle trigeneration system based on Compound Parabolic Collectors

During the last years, combined cooling, heating, and power (CCHP) systems have drawn a lot of attention thanks to their low greenhouse gas (GHG) emissions, high efficiency and cost benefits. Considering the increasing interest on sustainability assessment of novel energy generation technologies, in this paper a life cycle assessment of an innovative small-scale solar Organic Rankine Cycle (ORC) trigeneration plant is performed. The plant under investigation is composed of a 50 m(2) Compound Parabolic Collectors (CPC) solar field, a 3 m(3) diathermic oil storage tank, a 3.5 kW(e) ORC plant and a 17 kW, absorption chiller. After the set-up of the inventory data of the different subsystems, a sensitivity analysis of the environmental and energy performance of the plant has been conducted by varying: (i) the system adjustment parameters; (ii) the size of the solar field and the consequent solar multiple index of the plant; and (iii) the organic working fluid of the ORC unit. Results of the analysis confirmed that the Life cycle assessment (LCA) is of paramount importance for the appropriate selections of component specifications and operating conditions of the integrated system. In particular, the investigation has revealed that the variation of the adjustment parameters brings to slight modifications of the energy performance and has a limited impact on the environmental output whilst the proper selection of the working fluid and the size of the solar field can result in an appreciable environmental optimization of the whole plant.