Symbiotic and optimized energy supply for decarbonizing cheese production: An Italian case study

The use of renewable energy, including solar process heating, and of efficient energy conversion technologies, have been considered in the literature to improve the energy performance of cheese production. However, most of the studies considered one energy source at a time and hardly accounted for the carbon emission impact. In this paper, a mixed integer linear programming model is developed and applied to a reference cheese factory in Italy to identify the least cost mix of solar thermal energy, natural gas-based trigeneration and symbiotic waste heat recovery from nearby industries via district heating that allows to achieve assigned carbon emission reduction goals. The study reveals that fossil fuel based trigeneration is economically attractive, leading to savings in annual equivalent systems costs of approximately 18–20% over the baseline configuration, but does not contribute to decarbonization, generally causing a percentage increase of carbon emissions of approximately 30% from the baseline configuration. In addition, the combination of cogeneration and waste heat recovery from a remote source (300 m up to 1000 m far away from the user) may be more cost-efficient than solar heating to meet a 30% carbon emission reduction constraint for most combinations of electricity and natural gas prices.