Experimental Assessment of Energy Performance and Emissions of a Residential Microcogenerator

Microcogeneration systems, if correctly sized, managed and operated, can guarantee sensible primary energy savings and greenhouse gas emissions reductions in the residential sector. In this paper, the results of experimental tests carried out on a microcogenerator (5.5 kW electric power and 14.8 kW thermal power) based on a natural gas fuelled internal combustion engine, integrated with a condensing boiler, have b een analyzed. The tests were aimed at assessing the technical feasibility of the microcogeneration plant for residential applications, and at evaluating the possible energy and emissions savings it can achieve with respect to a benchmark scenario, based on separate “production” of electric and thermal energy. The tests have been performed at Institute for Energy Economy and Application Technology (IfE) of Technical University of Munich (Germany). The test facility allowed to simulate the thermal energy requ irements of a real residential application, represented by a Multi Family House consisting of 10 apartments, and to evaluate the energy flows of the conversion devices in actual operating conditions. Four type days, characteristic of Mediterranean climatic conditions, have been used to define space heating and domestic hot water user’s requirements. Experimental tests have been performed to implement energy and environmental analysis, comparing the system consisting of cogenerator and integration boiler wi th a reference system. Results showed that the former system can achieve a primary energy saving of about 6%, and CO 2 equivalent emissions reduction of about 12%. Finally, the algorithm defined by the European Directive on the promotion of high efficiency cogeneration has been implemented; it demonstrated that the primary energy saving is well above the limit value prescribed by the Directive. Therefore the cogeneration plant can access support mechanisms which can help to achieve the economic feasibility of the system, besides energy and environmental benefits.