Energy-economic analysis of a small-scale hybrid trigeneration system including biomass-fired steam cycle and wind turbine

In the last two decades, the concept of distributed generation changed the energy generation paradigm, determining a transition from centralised energy generation systems to diffused installations. An example of this transition is outlined by the fact that more and more small-scale energy systems have been installed over Europe in the recent years. In particular, a special category of such systems consists of hybrid plants where more than one renewable energy is used. In small-scale hybrid applications, the investigation of biomass and wind energy is scarcely addressed in literature with respect to other hybrid configurations, as biomass and solar. This paper presents a novel small-scale trigeneration system based on biomass combustion, water steam cycle, absorption chiller and wind turbine, suitable for rural areas where biomass resource was diffused and abundant. The system configuration included a bidirectional connection with the electric grid. The investigation of the system was performed by means of the TRNSYS software and includes the analysis of the dynamic operation of the system and the energy and economic assessment of its performance. The model of the installation was developed using build-in and user developed components based on manufacturer data as well as realistic user demand. In particular, the system was designed to properly manage its energy flows in order to match the user thermal and electrical demand. The dynamic operation of the system was investigated on a daily and monthly basis, while the assessment of the global system performance was performed on a yearly basis. The performance system was investigated for different design parameters (components capacities and set-point temperatures) and in case of a capital investment incentive strategy. The results show that the system allows one to achieve a significant saving of primary energy compared to a conventional system. However, the cost of the system was the main limit of presented technology in case of an absence of economic incentives.