Reducing Milk Spoilage Through Solar-Powered Chilling

Innovator (Country of Incorporation): 
United States
Hatsun Agro (India)
Orb Energy (India)
Location Applied: 
Innovation Stage: 
Agricultural Focus: 
Product Segment: 
Year of Award: 

Promethean Power Systems designs and manufactures refrigeration systems coupled to their thermal batteries for agricultural commercial refrigeration applications in off-grid and partially electrified areas of developing countries. Promethean is working in partnership with the Hatsun Argo—India’s largest private dairy company, and Orb Energy—a leading solar energy system provider in India.


In India, $10 billion worth of perishable foods are wasted annually because of unreliable cold-chain supply networks. A major obstacle in setting up cold chain networks is the lack of reliable electricity to run refrigeration systems in villages and farming areas. Diesel generators are often used to provide electricity for milk chilling, a non-ideal solution with high operating costs and negative environmental impact.

Clean Energy Solution: 

Promethean’s refrigeration solution uses a thermal energy battery pack that charges on intermittent power sources such as solar power and/or a few hours of grid electricity. This provides cold storage around the clock despite inconsistent access to electricity. Dairy processors can collect raw milk from remote dairy farmers and keep it cold in a rapid milk cooler, reducing the time that milk is unchilled by 75 percent. Promethean will design and deploy the refrigeration systems in collaboration with India’s largest private dairy and one of India’s largest solar installers.


India is the largest producer and consumer of milk in the world. Increasing access to milk while decreasing bacteria and spoilage supports food security and consumer health in India, where 42 percent of children under the age of five are malnourished. Promethean’s clean energy solution improves access to forward markets, higher income for the dairy farmers, and wealth creation through increase in herd size. Specifically, Promethean has observed the following positive impacts:

  • Promethean’s solution makes it viable for the dairy processors to set up more village level collection centers in the rural parts of India. The chilling infrastructure increases the overall income for the village by bringing more farmers into the organized collection of milk.
  • Rather than transporting the warm milk to a distant central chilling center, processors can eliminate middle-men and pay more money, with more transparency, directly to farmers.
  • The solution preserves the quality and eliminates spoilage. This reduces the financial risk to the farmers, as farmers only receive money for milk that makes it to the market, and improves the quality of milk that reaches the dairy processor.
  • When milk chilling technology is installed in a village, the whole ecosystem rises because farmers see permanent infrastructure that gives assurance that they will have an off-taker for their milk in the future. They therefore end up investing in more cows and grow their income over time. Data has confirmed that milk collection increases by up to 60-90% and farmers make about 10% more money per liter of milk once collection starts in their village.
  • The assured daily income also enables the smallholder farmer, many of whom are women, to invest in education, health and housing for their families.
  • Women benefit greatly from having a milk chiller in their village. They have a more flexible schedule for getting the milk to the milk collection area; the existing method has a strict timetable so that raw milk can be rushed to a distant center for chilling. The village-level milk chiller reduces this time constraint, allowing women to better balance their childrearing and farming responsibilities. The reliable income from getting their milk safely to market enables women to develop a financial cushion which they can utilize to invest in more cows to further grow their income or to spend on school fees for their children to enhance their future economic prospects.
Progress Update: 

By the end of the project in June 2017, Promethean sold over 600 units, of which they have deployed and commissioned over 460 milk chillers coupled to its patented Thermal Battery. Today this technology is enabling over 25,000 dairy farmers to chill their milk without diesel generators to get their milk to the market safely. None of the 250 Promethean chillers in the field have required a diesel generator. As deployment of the chillers continues, Promethean has been able to adapt the solar component design to address specific logistical needs of dairy partners and has seen increased adoption of the chilling solution as a result. Promethean’s solution gives farmers a larger time window to bring their milk to the village center so they can be more productive with crops and other income-generating tasks. It’s a win for the dairy processor because they collect more quality milk and they make more profits as value-added products demand high quality milk. It’s a win for the environment as there is no longer a need for pollution-causing diesel generators. It’s a win for the consumers because they are drinking healthier milk. And it’s a win for the farmers because their livelihoods improve.

Project News: 
Oct. 12, 2018

Promethean Power is one of 20 start-ups who will take center stage for Pitch Day in Singapore on October 26th. The top five will go to the finale on November 15th. The shortlisted start-ups are in the running to win the $15,000 Jury’s Prize and/or the $5,000 Audience Prize at the Finale. Good luck! 

Mar. 25, 2018

Promethean Power Systems' milk chillers are improving the bottom line for farmers. A dairy complex official put it this way: "This power system plays an important role in reducing loss that we faced earlier due to inadequate refrigeration and poor storage. The waste has reduced to 0.01% from 8%."