Did you know that Amul was created not with the sole intention of making profits, but to aid the dairy farmers in Anand, Gujarat? Their surplus milk was going to waste and they didn’t know what to do with it. Amul took this surplus milk to create plenty of milk and milk products, and the rest, as they say, is history.
The dairy industry in India has come a long way since then. Over the last decade, milk production in India has doubled, with an estimate 245.9 million tonnes produced annually in 2024, which constitutes a quarter of the world’s milk production!
Unfortunately, the dairy industry in India still relies on burning fossil fuels to produce heat, which results in poor system efficiencies and a higher carbon footprint.
Also, the waste heat from the processes is discharged into the surrounding environment without being used for recovery and utilization.
One of the things that is overlooked is the low-grade waste heat, which could be harnessed to produce useful thermal energy, which presents a substantial opportunity for energy, economic, and emission reductions.
A solution to these problems lies in what are known as Vapour Compression Heat Pumps (VCHPs) which help in energy-efficient process heating and industrial decarbonization.
VCHPs capture low-grade waste heat and upgrade it to useful temperature levels through closed-cycle mechanical compression, enabling the electrification of process heat while reducing reliance on fossil fuels.
70% of the total energy spent in a dairy processing plant is used for producing thermal energy for processes such as pasteurization, sterilization, etc. The remaining 30% is spent on electricity for chillers (for milk chilling and storage) and other processes.
To meet these energy demands, usually a single oversized boiler is used for supplying heat to all the required operations, resulting in reduced efficiency. Added to this, large refrigeration units are needed for cooling.
High-Temperature Heat Pumps (HTHPs) [at high temperatures above 80◦C, VCHPs are known as this] are a viable alternative to these boilers for the process heating operations. HTHPs are energy-efficient and low-carbon technologies, which make them an attractive alternative.
Many studies have been done on various heat pumps for application in dairy processing industries. The majority of the research has focused on investigating the energy performance of the systems. But very limited emphasis has been given to the economic assessment of these systems.
Therefore, in this study, the authors Dr. Nishant Modi, Mr. Aswin Raghunathan, Mr. Rajendra Kumar Martin, and Prof. Satyanarayanan Seshadri from Energy & Emissions Research Group (EnERG), Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology (IIT) Madras, Chennai, India (Mr. Aswin Raghunathan, Mr. Rajendra Kumar Martin, and Prof. Satyanarayanan Seshadri are also in collaboration with Trigen Decarbonisation Private Limited, Chennai, India), have carried out a techno-economic and environmental analysis for a VCHP to replace a wood-fired boiler for process heating in an Indian dairy plant.
Recoverable waste heat and daily heating demand were quantified using operational data from a dairy facility in India. The performance of the proposed system was compared with the wood-fired boiler in terms of energy efficiency, operational costs, and greenhouse gas (GHG) emissions.
A detailed economic assessment was carried out by systematically modelling Capital Expenditure (CAPEX), Operating Expenditure (OPEX), Simple Payback Period (SPP), etc.
This study demonstrates the strong potential of VCHPs to replace conventional boilers for dairy process heating. The system in this study delivered approximately 129% higher system efficiency, 13.40% lower heating costs, and up to 27% GHG reduction. Future work will focus on dynamic modelling of the integrated system to further optimize the performance and pilot-scale implementation to validate the numerical findings.
The paper provides crucial guidelines to industry stakeholders, consultants and policy makers for heat pump integration for industrial decarbonization.
Dr. Manish Rathod, Associate Professor at the Department of Mechanical Engineering at Sardar Vallabhbhai National Institute of Technology (SVNIT), Surat, India, appreciated the work done by the authors and pointed out their important achievements with the following comments: “This paper presents a highly commendable and timely contribution to industrial decarbonization, offering a rigorous techno-economic and environmental analysis of integrating a vapour compression heat pump to recover and upgrade waste heat in an Indian dairy plant. The authors demonstrate impressive methodological depth through detailed modeling, equipment sizing, and multi-criteria evaluation. They achieve notable performance gains such as a COP of up to 3.08, payback periods as short as 2–3 years in favorable regions, and 21–27% emission reductions. Their thoughtful sensitivity analyses on regional costs, alternative refrigerants, and integration strategies add significant practical value. Overall, this work provides a clear, scalable roadmap for replacing fossil-fuel boilers with energy-efficient heat pumps in the dairy industry and beyond.”
Article by Akshay Anantharaman
Click here for the original link to the paper
