A case study of a cogeneration system for a hospital in Greece. Economic and environmental impacts

The objective of the present work is to investigate whether a Hospital named “Tzaneio”, located in Piraeus, Greece, is a potential candidate for the implementation of a cogeneration system and also to determine the most suitable cogeneration system (electricity and heat). More specifically, after the presentation of the hospitalʹs energy consumption and the calculation of the energy consumption costs, alternative energy scenarios have been examined that propose the installation of cogeneration units of different power capacity for various profiles of operational hours. A comparative evaluation has been carried out for the selection of the most suitable CHP unit, following a specific procedure and taking into account a number of critical factors. The study showed that when the main gas engine (Diesel with natural gas) operates 8000 h/year and the backup unit 5000 h/year, the cogeneration system is most economically profitable. The total annual energy cost has been reduced by 32.4%. The Benefit-Cost Ratio (BCR) is greater than one, the Net Present Value (NPV) is positive and the Internal Rate Return (IRR) for 20 year lifetime of system is 19%. Also there is reduction of annual primary energy consumption by 28%, as well as a significant annual reduction of pollutant emissions.