International Journal of Greenhouse Gas Control 5 (2011) 1540–1549 Contents lists available at SciVerse ScienceDirect International Journal of Greenhouse Gas Control j our na l ho me p age: www.elsevier.com/locate/ijggc Greenhouse gas emission and exergo-environmental analyses of a trigeneration energy system Pouria Ahmadi ∗ , Marc A. Rosen, Ibrahim Dincer Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (UOIT), 2000 Simcoe St. North, Oshawa, ON, L1H 7K4, Canada a r t i c l e i n f o Article history: Received 20 March 2011 Received in revised form 17 August 2011 Accepted 19 August 2011 Available online 16 September 2011 Keywords: Exergy Energy Efficiency Trigeneration Cooling Heating Greenhouse gas emissions a b s t r a c t 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 sys- tem components, due to the high temperature difference between the working fluid and the flame temperature. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. 1. Introduction Energy concerns exist throughout the world. Limitations on supplies of energy resources are problematic and energy use con- tributes not only to global warming, but also to such environmental concerns as air pollution, acid precipitation, ozone depletion, forest destruction, and emission of radioactive substances (Dincer, 2000). These issues must be addressed if humanity is to avoid major soci- etal disruptions and environmental impact in the future (Dincer and Rosen, 1998; Ahmadi and Dincer, 2010; Dincer and Rosen, 1999). Advanced technologies to mitigate global warming are being proposed and tested in many countries. Among these technolo- gies, multi-generation processes including trigeneration can make important contributions due to their potential for high efficiencies as well as low operating costs and pollution emissions per energy output. Issues like fossil fuel depletion and climate change amplify the advantages and significance of efficient processes like trigener- ation. ∗ Corresponding author. E-mail addresses: Pouria.Ahmadi@uoit.ca (P. Ahmadi), Marc.Rosen@uoit.ca (M.A. Rosen), Ibrahim.Dincer@uoit.ca (I. Dincer). Trigeneration in power plants is the simultaneous production of heating, cooling and electricity from a common energy source. Trigeneration utilizes the waste heat of a power plant to improve overall thermal performance, essentially utilizing the “free” energy available via waste energy. In a trigeneration system, waste heat from the plant’s prime mover (e.g., gas turbine or diesel engine or organic Rankine cycle (Al-Sulaiman et al., 2010a)), sometimes with temperature enhancement, drives heating and cooling devices. The heat can be used for space heating, domestic hot water production or production of steam for process heating. The heat can be used for cooling, by driving an absorption chiller. The overall energy effi- ciency of a trigeneration plant can exceed 80% (Al-Sulaiman et al., 2010a). Energy analysis, which is based on the first law of thermo- dynamics, does not provide a clear picture or thermodynamic efficiency and losses. Exergy analysis overcomes these deficien- cies and can help identify pathways to sustainable development (Kanoglu et al., 2007). Exergy is a useful tool for determining the location, type and true magnitude of exergy losses, which appear in the form of either exergy destruction or waste exergy emission (Dincer and Rosen, 2007). Therefore, exergy can assist in developing strategies and guidelines for more effective use of energy resources and technologies. Furthermore, exergo-economics, which com- bines exergy analysis with economic principles, can facilitate 1750-5836/$ – see front matter. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.ijggc.2011.08.011