In 2007 Sam White, co-founder of Promethean Power Systems, was traveling through India looking for a rural electrification problem to solve. He and his team had just won a $10,000 grant in an MIT competition, and they wanted to find an industry in India that needed their help. After looking at the sugar industry and the grape industry, they finally settled on dairy. 

 India is the largest producer and consumer of milk in the world, but poor infrastructure makes getting chilled milk from farmer to consumer difficult.  Industry standards require milk to be chilled within four hours of milking the cows, or bacteria spoils it. India averages six hours.

Sam’s team had found their problem. But it would take years of failed designs to solve it. In the end they perfected a 500 liter tank that could chill a thousand liters of milk – a 300% increase in efficiency from previous designs. Today, Promethean had installed 2800 of those tanks across India.

 In this episode, Lara Pierpoint talks with Sam about the evolution of Promethean's thermal battery design, the upsides of slow but steady growth in climate tech, and how Promethean dealt with technology copycats in India.