A tri-generation plant fuelled with olive tree pruning residues in Apulia: An energetic and economic analysis

This paper presents the energetic and economic analysis of a virtuous example consisting of a trigeneration system fuelled only with olive tree pruning residues and planned to be located next to Bari Airport (Apulia, Italy). The main goal is to demonstrate the feasibility and convenience of producing cooling, heating and electrical power from olive tree pruning residues in those regions characterized by a high availability of this kind of biomass, such as Apulia. A strategic location was selected, namely Bari Airport (Apulia), and this paper demonstrates the economic convenience of installing a commercially available Organic Rankine Cycle (ORC) unit of 280 kWe that is capable of satisfying the thermal demands of the airport, with the addition of an absorption chiller for air conditioning in the airport buildings. First it is verified that the quantity of oil tree pruning residues available in the area surrounding the airport fully can satisfy the plant demand of feedstock. Then a detailed description of the components of the plant is provided. The performance of the plant is therefore evaluated in order to assess the thermodynamic competitiveness of a tri-generative system fuelled with this type of biomass. Finally, a detailed economic analysis is carried out with the aim of demonstrating the advantages that the plant can assure in terms of payback period (PBP), net present value (NPV) and internal rate of return (IRR). Two different typologies of government incentives are considered. In both of which, the PBP is 6 years with an IRR of about 21% and this points out the great economic attractiveness of the project. From an ecological point of view, the plant can ensure a remarkable reduction in CO2 emissions.