Small scale decentralized polygeneration systems

In recent years great attention, both in the research and in the application, has been focused on the transitionfrom centralized to decentralized energy “production” systems, (Decentralized or Distributed Generation, DG). Thisprocess is already partially being carried out and, in the technical and scientific literature, the benefits and drawbacksthat DG will provide to the end-user and to the community have been analyzed. Furthermore the actual industrial trendto the miniaturization of the energy conversion equipments, mainly due to reduce manufacturing costs, has led to theavailability of a wide variety of small scale power, refrigeration and heat pump systems in the market. By avoiding orreducing transmission/distribution and energy cycling losses and costs, DG can provide lower operating costs in manycases. Unfortunately, considering small scale energy conversion systems, it is important to highlight that there is areduction of the performance with the size. Therefore, since the “size” effect does not always lead to energy savingsand reduction in the emission of pollutants, there is the need to support the diffusion of on-site small complex energyconversion devices, Decentralized Cogeneration and Decentralized Polygeneration, DP, capable of supplying, withhigh performance, two or more energy requirements (electric, cooling and heating) of the end-user rather than thesimple single-output equipments. In other words electrical efficiency may be reduced but the fact that multiple energystreams are captured with smaller plants more than makes up for this. In many sectors small scale energy conversionplants (Polygeneration, Trigeneration, Combined Cooling Heating and Power, CCHP) allow to satisfy different energyrequirements (electricity, cooling and heating) with a great potential of primary energy saving and greenhouse gasemission reduction. In this paper different CCHP systems were described and the results of studies conducted on themusing different approaches, theoretical, experimental and on-site analysis, were reviewed. Finally the Energetic,Economic and Environmental implications due to the use of these complex energy conversion systems were reported,starting by an intensive theoretical and experimental research activity performed by the authors and other researchers.