A Review of Indices and Methodologies for the Performance Assessment of Cogeneration and Trigeneration Systems

Cogeneration and trigeneration systems can contribute to the reduction of primary energyconsumption and greenhouse gas emissions in residential and tertiary sectors, by reducingfossil fuels demand and grid losses with respect to conventional systems. To evaluate theperformance of these systems, several indices and assessment methodologies can be used, dueto the high complexity of such systems, which can consist of several energy conversiondevices and can perform bidirectional interactions with external electric and thermal grids. Inthis paper, a review of the available indices and methodologies to assess the performances ofpolygeneration systems, is provided. This activity started in the framework of theInternational Energy Agency Annex 54 project (“Integration of Micro-Generation and RelatedEnergy Technologies in Buildings”), where research group shared their expertise aboutmethods applied in each country to evaluate the performance of polygeneration systems. Itwas concluded that a thermo-economic analysis comparing the performance of apolygeneration system with those of a reference benchmark scenario, is a very suitableassessment method. Some of the reviewed methodologies are then applied to commercialsmall scale cogenerators.