twice a day, in the morning and late afternoon, rural farmers in indian villages carry milk from their homes in metal containers to a central area where it is aggregated for the community to share. the central collection container is connected to the power grid, but it is unreliable and often villages are left without electricity during the collection times because that is when power is needed in the major cities.

without electricity, the milk that is collected spoils quickly. this leads to unhealthy conditions for villagers and limits the amount of milk that a farmer or a dairy would be willing to collect in a day. india is the largest consumer and producer of milk in the world, so this was a considerable issue.

(wikimedia commons)

in 2007, mit student sorin grama created a thermal battery that he hoped would prove a godsend for the developing world. his intention was to use the battery to store power when the grid was working properly and then to use it to heat water. boiled water could be used to sterilize medical tools for instance, but when he took his invention, for which he received second prize in mit’s entrepreneurship competition, to india he was told that it was not hot water but cold milk that was needed.

grama took his original idea and adapted it to the needs of the market. he created promethean power systems with classmate sam white and used his patent-pending thermal battery technology to build a line of milk chillers and refrigeration systems that preserve milk, fruit, and vegetables.

since 2007, promethean power systems has sold more than 100 chillers, which help an average of 20-30 farmers apiece. food producers can save perishable items, consumers are able to get healthier milk and food, and farmers and dairies can start to produce more products and better values.

grama applied for a patent for his thermal battery in 2014. according to the patent abstract, the battery utilizes an insulated tank that is densely packed with plastic tubes that are filled with phase change material (such as ice). the material changes from solid to liquid and back. energy is stored when the phase change material solidifies and then is released when it melts.

the tubes are surrounded by heat transfer fluid (htf), an aqueous solution with a freezing point below that of the phase change material. the htf remains liquid when the battery is in operation and diffusers in the battery allow the htf to be extracted and cooled by a liquid chiller outside the tank before being reinserted.

the new cooling technology has proven to be a great success for promethean power systems and, more importantly, for the villagers of india who take advantage of the technology to ensure their milk remains cold.

learn more about sorin grama in this story from pri.org: http://www.pri.org/stories/2016-08-23/mit-lesson-failure-helps-deliver-fresh-milk-millions-india. to find more information on the products that promethean power systems provides, visit http://www.coolectrica.com/#homecoolectrica.

also, watch the video below to find out more about how promethean power systems is helping people in the developing world: