Milk Storage Unit Uses Sun to Keep Cool

Tuesday, June 28, 2011

Got chilled milk?

That’s the unofficial slogan for Boston-based Promethean Power Systems, a company that this month received a grant from the National Science Foundation to further develop its innovative milk refrigeration system.

Promethean’s target market is India, though it plans to expand to Africa and Latin America as soon as February. India is the world’s largest producer and consumer of milk; the country is home to some 70 million farmers who contribute to a multibillion-dollar dairy market.

Because temperatures can reach 100 degrees during peak summer months, raw milk begins to spoil within hours of collection. And India’s frequent blackouts, due to a strained power grid, make it difficult to keep milk cold enough.

Enter Sam White and Sorin Grama, cofounders of Promethean, who have found a way around this problem by creating a system that’s partially off the grid. By using solar power – India has 250 to 300 sunny days a year – dairy processors receive a constant flow of energy, which means a steadier and fresher supply of milk.

Their hybrid milk chiller gets half its electricity from the grid and half from solar, which is all stored in a thermal energy battery. By splitting the supply between traditional and solar power, the cofounders say, operating costs are 50 percent lower than a comparable grid-powered unit and 80 percent lower than a diesel-powered unit.

With a more efficient and reliable system, processors can collect milk from farmers every other day, which means huge savings in transportation costs in addition to the savings from milk that would have gone bad. With traditional refrigeration systems that rely on electricity, 50 percent of milk spoils from inadequate insulation.

“We were like, bingo! That is a big problem we could solve,’’ said White, recalling an initial conversation he had with S. Sunder Ram, managing director of Bangalore Dairy.

White and Grama first came up with the idea during a 2007 scouting trip to India. White had quit his job and Grama had recently graduated from the Massachusetts Institute of Technology’s System Design and Management Program. With a $10,000 runner-up prize from the MIT $100K Entrepreneurship Competition, they set out to find inspiration abroad.

“It was a serendipitous moment,’’ Grama said of meeting Ram. “We were in India looking for business opportunities when Sam cold-called Bangalore Dairy and they said: ’We have a problem with milk chilling; come on over and we’ll tell you all about it.’ So that changed our careers and, we’ve been focusing exclusively on this market ever since.’’

Source: (link opens in a new window)