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: 
Financing Status: 

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: 

Promethean has now sold over 400 units, of which they have deployed and commissioned over 250 milk chillers coupled to its patented Thermal Battery. The remaining units are pending installation or are in production today. To date, none of the 250 Promethean chillers in the field have required a diesel generator. Without Promethean’s Thermal Battery, a traditional milk chiller would have run diesel generators to chill milk in these villages, leading to higher costs and increased carbon emissions, or milk chillers would not have been installed at all, leading to greater spoilage and decreased quality of milk. 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 have seen increased adoption of the chilling solution as a result.

Project News: 
Apr. 18, 2017

Indian cleantech startups often struggle to find the talent needed to build an effective team. From "feet on the street" to senior leadership, authentic knowledge of the complex Indian market is key. A leader in this developing market, Promethean is being watched as they negotiate these challenges.

Feb. 22, 2017

Promethean's system allows for chilling milk at source, which is a win-win for dairy plants and farmers. Dairies get milk with less microbial load and spoilage possibility; farmers benefit from a more flexible delivery time and increased herd size. They can also expect to fetch a better price.

Jan. 31, 2017

Word is spreading about the transformative impact of Promethean's milk chiller technology. The company has sold over 500 milk chilling units to its dairy partners in India, Sri Lanka and Bangladesh. Retailers are also using Promethean’s system for refrigerating produce.

Jan. 29, 2017

Sorin Grama and Sam White of Promethean Power are finding their stride in India, where their thermal energy storage technology is making a real difference in the lives of Indian dairy farmers—without using a single drop of diesel.