How optimally selecting among internal and external opportunities for waste heat valorization: a case study from the steel industry

Concerning waste heat recovery projects, especially in the energy-intensive industrial sectors, facility managers face indeed the challenge of making the optimal strategic choice within the different waste heat recovery options. In this context only the two energy recovery options based on a smart energy system approach, namely, power generation through an Organic Rankine Cycle (ORC) unit (both for self-consumption and grid selling) and the exploitation of the generated heat transfer fluid to feed an urban DH network. The economic objective represents the main driver, although environmental objectives are becoming increasingly important, also thanks to the rising value of green marketing. Indeed, when both the potential demand from external users and the opportunity to produce electricity represent attractive options, in order to allow the facility manager to select the most suitable waste heat recovery option and to decide which project to endorse, a deeper insight on the sustainability performances of each potential waste heat recovery solution is required. The developed DSS framework has then been applied adopting a facility manager’s perspective, with the aim to investigate the economic, energetic and environmental performances of different options for waste heat recovery exploitation, thus allowing a strategic decision making for the endorsement of the related investments. The model application provided useful suggestions on the optimal configuration of the energy recovery system, i.e. the selection of the most suitable option for the exploitation of the recovered energy, also taking into account the possible combination of different technologies, their optimal sizing and the definition of the operational strategy.