Please cite this article in press as: Gharaie, M., et al., Retrofit strategy for the site-wide mitigation of CO 2 emissions in the process industries. Chem. Eng. Res. Des. (2014), http://dx.doi.org/10.1016/j.cherd.2014.08.007 ARTICLE IN PRESS CHERD-1670; No. of Pages 29 chemical engineering research and design x x x ( 2 0 1 4 ) xxx–xxx Contents lists available at ScienceDirect Chemical Engineering Research and Design j ourna l h omepage: www.elsevier.com/locate/cherd Retrofit strategy for the site-wide mitigation of CO 2 emissions in the process industries Mona Gharaie a,* , M. Hassan Panjeshahi b , Jin-Kuk Kim c , Megan Jobson a , Robin Smith a a Centre for Process Integration, School of Chemical Engineering and Analytical Science, The University of Manchester, The Mill, Sackville Street, Manchester M13 9PL, UK b Department of Chemical Engineering, College of Engineering, University of Tehran, PO Box 11155-4563, Tehran, Iran c Department of Chemical Engineering, Hanyang University, 222 Wangshimni-ro, Seongdong-gu, Seoul 133-791, Republic of Korea a b s t r a c t The combustion of fossil fuels for providing heat and power in the process industries is a major contributor of CO 2 emissions. Heat integration methods have been widely used for energy-saving retrofit projects to improve the energy efficiency of process plants, reducing fuel consumed and consequently CO 2 emissions. It is not straightforward to identify the most appropriate strategy for CO 2 emissions reduction, as a wide range of options are available, includ- ing fuel switching, reducing energy demand through efficiency improvements, retrofit of heat exchanger networks, etc. The economic impact and design constraints of each option need to be considered. A systematic approach is presented to allow evaluation of trade-offs between the cost of emissions reduction options and the effect on over- all CO 2 emissions. The approach applies a hierarchical conceptual design procedure. The proposed procedure is applied to a case study to demonstrate how an economic retrofit solution to reducing site-wide CO 2 emissions can be systematically developed and evaluated. © 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Keywords: Process integration; Retrofit; Energy saving; Fuel switching; CO 2 emissions reduction; Carbon tax 1. Introduction Recent analysis by the International Energy Agency (IEA) esti- mated that the energy production by utilization fossil fuels accounts for about 65% of global greenhouse gas (GHG) emis- sions (IEA, 2012). New environmental legislation to control CO 2 emissions is putting increasing pressure on the process industries, for example through the European Union Emis- sions Trading Scheme (EU ETS, 2012). Such legislation imposes a limit on carbon emissions by industrial emitters, sets emis- sions reduction target, and applies economic penalties in some cases. Retrofitting process plants to improve energy efficiency has proved to be a beneficial option for reducing CO 2 emissions (Mahmoud et al., 2009). Avoiding inefficient use of energy ∗ Corresponding author. Tel.: +44 161 2004390. E-mail address: mona.gharaie@manchester.ac.uk (M. Gharaie). through better operating practice or improved process design can decrease fuel consumption and hence flue gas emissions. The retrofit of a process plant for energy savings can be carried out by increasing heat recovery in its heat exchanger networks (HENs) and its steam and power system, utility system. A wide range of process design methodologies, many of which apply process integration concepts for saving energy, has been devel- oped and successfully applied to improve the energy efficiency of existing process sites (Gharaie et al., 2011). Significant efforts have been made to improve energy efficiency in the process industries to reduce the CO 2 emis- sions (e.g. Mahmoud et al., 2009; Tiew et al., 2012). Mahmoud et al. (2009) developed a graphical methodology for combined energy saving project and fuel switching with the objective of CO 2 emissions reduction. In this method, for a given emissions http://dx.doi.org/10.1016/j.cherd.2014.08.007 0263-8762/© 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.