Energy conservation in the dairy industry: A critical review

Abstract:

The dairy industry is an energy-intensive food-processing sector in which thermal and electrical energy are required throughout milk reception, pasteurization, sterilization, evaporation, drying, refrigeration, cleaning and packaging. This review critically examines energy-use patterns in dairy processing and evaluates major strategies for energy conservation, including heat regeneration, waste-heat recovery, boiler optimization, refrigeration efficiency, insulation, variable-speed drives, efficient pumping, optimized clean-in-place systems, process integration, renewable-energy utilization and digital energy management. Among the major operations, heating, evaporation and drying are particularly important thermal-energy consumers, while refrigeration, compressed air, pumping and agitation contribute substantially to electrical demand. Regenerative heat exchange in pasteurization is one of the most established opportunities because it can recover a large proportion of heat from the outgoing product stream. Additional opportunities exist through condensate recovery, economizers, heat pumps, mechanical and thermal vapour recompression, membrane concentration, multi-effect evaporation, improved dryer operation and refrigeration-system optimization. However, energy-saving measures must be evaluated against food-safety requirements, product quality, capital cost, maintenance, process reliability and water consumption. Renewable-energy systems such as solar thermal, photovoltaic power, biogas from dairy effluent and anaerobic digestion of organic residues can reduce dependence on fossil fuels, particularly when integrated with energy-efficiency measures. The review identifies major research gaps in plant-level benchmarking, integrated energy-water optimization, digital monitoring, low-carbon heat, thermal storage and techno-economic assessment. Future dairy plants should move from isolated equipment-level interventions toward integrated energy management based on process heat cascading, electrification, renewable energy and data-driven optimization. Such approaches can simultaneously reduce operating costs, greenhouse-gas emissions and resource consumption while maintaining food safety and product quality.