Energy, exergy, economic and exergoeconomic (4E) multicriteria analysis of an industrial waste heat valorization system through district heating

International audienceThe purpose of this article is to determine the multicriteria-optimal design of an industrial waste heat recovery system for district heating in Grenoble (France). Energy, exergy and cost flow balances were applied unit by unit allowing to assess the process performance based on two innovative methods. First, the performance assessment includes all units involved in the heat valorization process, not only focusing on the recovery system. Second, the yearly management of energy flows was optimized through mixed-integer linear programming, anticipating fluctuations in residential demands and waste heat availability. This multicriteria analysis with a systemic-anticipatory approach allowed to select the appropriate inlet temperature and storage capacity. It was found that the most promising inlet temperature and heat storage capacity are 35 degrees C and 30 MWh, respectively. With this design, the system recovers 41% of industrial waste heat, covers 48% of residential needs, has an estimated net present value of 11.7 million euros over 20 years, and reduces the district's overall exergy destruction and exergy destruction costs by 20% (4.2 GWh/year) and 9% (286 k(sic)/year), respectively. Remarkably, none of the mono-criterion analyses prioritized this design. Therefore, the multicriteria analysis with systemic-anticipatory approach was of utmost importance for detecting the most promising solution