India is the world’s leading milk producer, with many of its people relying on milk as a primary source of income. Indian dairies buy milk from local farmers at village collection centers, and then sell the milk or use it to make dairy products.
But with rural India’s limited electric grid, often available for only several hours daily, keeping milk fresh — it must be refrigerated within a few hours of milking — becomes very difficult. Many dairies use expensive diesel generators for refrigeration, or risk high percentages of spoiled product: Of the roughly 130 million tons of milk produced by India each year, millions of tons go to waste or reach the market as low-quality dairy products that pose safety threats. All this also reduces the income of Indian farmers
Now MIT startup Promethean Power is bringing India milk-chillers that quickly drop the temperature of milk to reduce bacterial growth, even without electricity. Powering the chillers is a novel thermal battery that stores thermal energy when the grid’s available, and releases the energy without need of electricity. So far, Promethean has installed about 100 chillers for top dairies around India.
“Milk for many Indian farmers is literally like liquid cash,” says Promethean co-founder and chief technology officer Sorin Grama SM ’06. “An entire family may live off the money they make from milk. Each of our systems allows 20 to 30 farming families to generate a steady income by selling a portion of their milk to dairy processors.” Read more.