Energetic and economic analysis of trigeneration for San Nicola Building

Liberalization of electrical energy sector in Italy has opened new scenarios to distributed generation and small cogeneration that are technologies considered very interesting from both the energetic and polluting emissions point of views. “S. Nicola” is an historic building in the centre town of Vicenza (Italy), renovated during ‘90s and which houses the headquarters of the Department of Management and Engineering of the University of Padua. HVAC plant features quite innovative and significant energy savings characteristics. It has been set up by a gas engine reversible heat pump (GEHP) coupled to two condensing boilers. Recently, during the last years some failures of the GEHP have requested extraordinary maintenance. Furthermore, gas engine half-life maintenance is necessary in the next months (approaching 15000 hours working). For these reasons, it is interesting to compare, both from energetic and from economic point of view, the actual solution with a trigeneration plant. The latter provides electrical energy that, depending on the period of the day, can partially or completely satisfy the load of the building or be exchanged with the local distributor grid. Heat recovered from the cogenerator can be suitably used to produce profitable relatively hot water in winter and refrigerated water in summer by means of an absorption chiller. Thermal loads of the building have been determinate by transient simulations by means of Trnsys. Energy performances of the proposed systems (different type of cogenerators and operation strategies are taken into consideration) are compared to those of the actual solution. The results show interesting primary energy savings in many cases, allowing also economic and environmental benefits.