Energy and economic analysis of a small hybrid solar-geothermal trigeneration system: A dynamic approach

This work presents a dynamic simulation model of a prototypal renewable plant producing electricity, heat and cool. The hybrid system consists of a 6 kWe Organic Rankine Cycle (ORC), a 17.1 kWf absorption chiller, a geothermal well, a 25 m2 evacuated solar collector field, a 200 kWt biomass heater and a 45.56 kWh electric energy lithium-ion storage system. The geothermal well at 96 °C, in combination with the solar field, supplies the thermal energy driving the ORC. This simulation model is implemented in TRNSYS environment. In order to evaluate the thermoeconomic performance of this renewable trigeneration plant, a suitable case study is analysed: a bar and soccer centre in the area of Campi Flegrei (Naples). By the simulation, interesting results in terms of energy and environmental performance are obtained. The proposed renewable power plant achieves a primary energy saving of 94.54% and a reduction of CO2 emissions equal to 97.36%. The high total capital cost of the plant significantly affects the payback period of 16.7 years. However, in the future European energy scenarios, where a full decarbonization will be achieved and the capital cost of the renewables will significantly decrease, the use of these technologies will be pivotal and significantly profitable.