Energy and Environmental Performance Analysis of Industrial Cogeneration and Trigeneration Plants: The Impact of Actual Global Efficiency

The use of cogeneration and trigeneration systems in industry, also due to favourable price conditions until 2021, has seen significant development over the past decade. However, if we analyse the final performance of a significant sample of plants, distributed across different industrial sectors (chemical, pharmaceutical, tanning, and others) and in district heating, it emerges that the average global efficiency of the plants is very often far from the 75% target. If from an economic point of view the impact is variable depending on the prices of the energy vectors, in terms of primary energy savings and, above all, the actual reduction of greenhouse gas emissions compared to separate generation, in some cases the results are much lower than expected. The paper presents an analysis of a set of cogeneration and trigeneration plants and highlights the variability of main drivers (primary energy, greenhouse gas emissions, and economic profitability) in function of the global performance, underlining the critical issues that also lead to a reduction in the final global efficiency compared to expectations.