Greenhouse gas emission and exergo-environmental analyses of a trigeneration energy system

A comprehensive thermodynamic modeling is reported of a trigeneration system for cooling, heating and electricity purposes. This trigeneration system consists of a gas turbine cycle, a steam turbine cycle and a single-effect absorption chiller. Energy and exergy analyses, environmental impact assessments and related parametric studies are carried out, and parameters that measure environmental impact and sustainability are evaluated. The exergy efficiency of the trigeneration system is found to be higher than that for typical combined heat and power systems or gas turbine cycles. The results also indicate that the carbon dioxide emissions for the trigeneration system are less than those for the compared systems. The parametric investigations show that compressor pressure ratio, the gas turbine inlet temperature, the gas turbine isentropic efficiency and the heat recovery steam generator pressure significantly affect the exergy efficiency and environmental impact of the trigeneration system. The results also show that compressor pressure ratio and turbine inlet temperature decreases the cost of environmental impact, primarily by reducing the combustion chamber mass flow rate. The evaluation of the exergy efficiency, exergy destruction, carbon dioxide emission and cost of environmental impacts for each case and the overall cycle demonstrate that the combustion chamber has the highest exergy destruction of all system components, due to the high temperature difference between the working fluid and the flame temperature.

► Development of a new integrated thermodynamic approach with exergo-environmental analyses.
► Application to trigeneration energy systems.
► Connection to sustainability index and environmental impact parameters.
► Proposal of various performance measures to reduce carbon dioxide emissions.
► Discussion of the role of trigeneration systems and exergo-environmental analysis as a potential tool for more environmentally-benign applications.