ECONOMIC IMPACT OF RETROFIT SOLUTIONS APPLIED TO A TRIGENERATION PLANT CONNECTED TO A DHC NETWORK IN COMPLIANCE WITH THE TRANSPOSITION OF THE EU DIRECTIVES.

This work presents the results of a technical and economical analysis pursued to investigate an upgrading of a Trigeneration District Heating and Cooling (DHC) plant located in the City of Trento (Northen Italy) actually fed with methane. This was necessary to comply with the requirements introduced by the Directive EU) 2023/1791 which establishes, from 2028 onwards, a minimum share of 5% of heat produced from renewable or waste heat resources to achieve the qualification of Efficient DHC, with progressively stricter thresholds in the following years. A comprehensive analysis of all the components of the plant has been preliminary carried out based on exercise data of the year 2024. Several scenarios, integrating different renewables technologies, are implemented. Among the investigate solutions, the installation of geothermal heat pumps, open or closed circuit, to preheat the DHC return flow before feeding the CHP, has emerged as the most effective. The economic feasibility is strongly dependent from the operating time of the CHP unit. The proposed approach can serve as a procedural framework to be applied to similar plants to comply with the EU directives currently in force.