A case study of existing industrial trigeneration. Operating conditions analysis and revamping opportunities.

In Italy renewable energy sources (RES) covered the 18,2% of the gross final energy consumption in 2019, thus, exceeding the target of 17,0% renewables, assigned for the year 2020 by the Directive 2009/28/CE. While electricity and transport sector showed an increase of RES consumption, in absolute terms, a slight reduction of thermal energy production from RES has been observed. However, this last decrease was compensated by a greater decline of gross final energy consumption; consequently, all the three sectors were characterized by an increase of RES penetration, in percentage terms. Industry is one of the main energy intensive sector in Italy, as it accounts for around 21% of final energy consumption; however, the reduction with respect to the previous year (-0,9 %) and the continuous decline of industrial sector energy intensity show that we are exploiting primary energy sources more and more efficiently. Energy efficiency, indeed, will play a key role to achieve the target of net-zero emissions in the EU energy systems by 2050. For this reason, it is fundamental to initiate energy efficiency processes in the residential sector and on cogeneration and trigeneration existing plants, in order to produce electricity and thermal energy from fossil fuels in a more sustainable and efficient way, supporting the industrial sector towards a decarbonization that does not compromise the productions. This Thesis work has been carried out in collaboration with Edison Fenice S.p.A, in particular with the Energy and Environmental Service Division that focuses on the development and the operation of energy efficiency projects and environmental services for large industrial customers, small and medium companies, the service sector and the public administration. This study analyzes a trigeneration plant owned by Fenice S.p.A and located in Melfi (PZ), at the service of the Plastic Components and Modules Automotive (PCMA) industrial site of the Stellantis Group. Starting from the energy plant data obtained from the Online Data Collector, a data analysis has been performed in order to evaluate the Internal Combustion Engine (ICE) performance and the effectiveness of heat recovery and cold water production. The analysis considers three years of operation (the year 2020 because of the Covid-19 pandemic that affected the industrial site productivity and, as a consequence, also the trigeneration plant operation was not included in the analysis) in order to examine more completely the evolution over time of the energy vectors provided to the PCMA industrial site and, thus, to evaluate the dimensioning of the various energy plant components. Starting from some criticalities highlighted by the analysis of plant operating data, some opportunities of energy efficiency optimization are investigated, particularly on the heat recovery from the ICE exhaust gases and on cold water production by means of water absorption refrigerator groups. The different optimization scenarios are completed with an economic analysis to evaluate the money savings with respect to the original plant configuration, due to the possibility to improve energy efficiency and to obtain a higher number of White Certificates intended for High Efficiency Cogeneration plants. In the last section of this study, there are presented some considerations on CO2 emissions and possible future negative implications on the analyzed trigeneration plant economic balance because of stricter Emission Trading System regulations.