Estimating the Potential for Waste Heat Recovery in Italian Dairy Sector Using a Bottom-Up Approach and Data from Energy Audits

As a result of the expected increase in food demand, improving the sustainability of the food industry has become a priority worldwide. The recovery of industrial waste heat is widely regarded as a key strategy to reduce the energy consumption and greenhouse gas emissions of food manufacturing processes. Estimating the available recoverable waste heat can contribute to driving actions that promote the effective exploitation of such an untapped energy source. This study aimed to evaluate the waste heat potential of large and energy-intensive Italian dairy companies. To this end, a methodology that combined key transfer figures adapted to the Italian industrial context and data on fossil fuels consumption from energy audits was adopted to assess the technical waste heat potential. A comparison with the overall waste heat recovered from the projects proposed by large and energy-intensive dairy companies was carried out to estimate the residual waste heat available. Finally, the economic waste heat potential was assessed by varying the heat transfer operating conditions between the waste heat sources and sinks, and assuming that waste heat recovery was operated through heat exchanger technology. The technical waste heat potential of large and energy-intensive dairy industries was valued at roughly 75.6 GWh(t)/year. Simulation results also showed that more than 90% of the studied companies exhibited payback periods below three years for all waste heat recovery projects, except for those involving gas-to-gas or gas-to-liquid heat transfers.