ABSTRACT
Besides acknowledging that cogeneration improves fuel efficiency, renewable energy use in cogeneration for sustainability receives little attention. This entry focuses on the energy and exergy benefits of cogeneration and trigeneration for better and wider utilization of renewable energy resources. Specific applications such as building integrated solar trigeneration on facades, wind turbine and small hydro‐turbine‐coupled heat pumps, and PV‐hybrid tubular day‐lighting devices, all of which primarily serve green buildings and cities, are presented, emphasizing that virtually any system may be transformed to a cogeneration system with a mind‐set of utilizing renewable energy resources wherever available and possible. These examples also emphasize that optimum utilization of renewable energy resources may be enhanced by a hybridization approach while improving the exergy supply and demand balances. In the quest for laying a solid groundwork for theory and application, the available rating parameters designed for fossil fuels given in the EU 2004/8/EC Directive are summarized first and then expanded to renewables using new exergy‐based rating and metricating parameters using the Rational Exergy Management Model. These parameters are applied to a case study to exemplify their contributions to better utilization of renewable energy systems in cogeneration.
