Promethean Power Systems

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Revolutionizing Rural Cold Storage



Headquarters Cambridge, Massachusetts, USA
Established 2007
Impact Areas India, Pune
Type For-Profit
Energy Sectors
Business Model Types
Staff Size 5
Annual Budget N/A
Major Funders Quercus Trust, Gray Matters, Invested Development co-founder Sun Edison, Solgenix
Awards 2007: Runner-up, MIT $100K Competition
2010: CSTS Global Social Benefit Incubator, GE Ecomagination Honorable Mention


Promethean Power Systems has developed a rapid-cooling milk chiller sold to dairy processors in India.


Energy Products/Services

Target Market

  • Dairy processors who have not been able to collect enough quality milk to meet demand, which is growing at 6% annually
  • Milk producers whose milk gets spoiled because it is not collected in time are also beneficiaries, though they cannot afford the purchase price of the chillers.


Promethean Power Systems

Revenue Streams

  • Sale of rapid-cooling milk chillers

Value Proposition

  • The system preserves milk at the village level, which reduces spoilage and transportation costs for processors, leading to increased farmer incomes.
  • The chillers enable processors to collect milk that has been chilled at the source, which improves the quality of milk and enables them to collect from isolated dairy villages.
  • The system is powered by the grid and by a generator when the grid is down, but will in future use a thermal battery backup to store grid energy.

Problem Addressed

  • US$33 billion worth of agricultural produce spoils every year in India.
  • In the United States, 82% of food grown on farms gets processed and in India, only 6% gets processed.
  • The biggest obstacle to this industry’s growth is that farmers are not able to preserve the food they grow on their farms due to a lack of reliable electricity.

Where They Are Now

Impact to Date

  • One product purchase order received from Hatsun, India’s largest private dairy.
  • Trial orders received for chillers from the top 3 dairies in India, including Amul.
  • Increased price paid to farmers from $0.18 to $0.60 per liter


  • 2007: Won second place at MIT business plan competition
  • 2007: Discovered milk chilling problem during visit to rural India
  • 2008: Completed First Prototype
  • 2008: Closed round of funding
  • 2009: Formal human factors study in rural India
  • 2010: Completed 2nd prototype using parts in India
  • 2010: Inaugurated prototype with Goa Dairy. First farmer to chill milk
  • 2011: Trial orders received from Amul and two other top dairies in India

Growth Plan

  • Promethean is currently trying to finalize industrial design and execute on its first 5 orders.
  • Break-even is projected for 2012

How They Deliver

Product Sourcing

  • Promethean’s chiller was originally developed as an Organic Rankine Cycle (steam powered heat engine) made out of old car parts, for use in Lesotho.
  • Promethean manufactures in India, using Indian parts.
  • Promethean has been honing its technology over the past 3 years through field testing and modification.  It has gone through several iterations, including an ice chiller, to reach its current design.
  • The Promethean chiller’s main value adds are (1) an extremely efficient cooling system and (2) a ‘Cold Storage Battery Backup,’ which stores cooling capacity anytime there is 5 hours of power, to be used when needed, decoupling energy availability from energy use,  and allowing milk to be chilled even when the power is out.
  • Because it can utilize the irregular grid power that is received for 6 to 8 hours a day, Promethean’s system eliminates the need for a diesel generator set.  This makes it economically viable for dairy processors to place milk chillers at the village level, where the milk is being produced.
  • The chiller was originally powered by a solar panel, but in order to reduce costs and maximize portability, they have, for the time being, removed it.  Cost has now gone from US$12,000 to US$4,000, and the system is now much smaller and easier to transport to more remote villages.
  • Promethean will consider reincorporating solar into their units once they gain more market traction.  This would increase operating cost but might reduce up-front expenditure enough to be worth it.



  • Promethean sells its chillers to large-scale processors, who can reduce the number of daily trips they have to make to collection centers and increase the quality of the milk they sell.
  • Promethean’s current primary partner, Hatsun Dairy, has been helping Promethean develop its product and distribution.
  • Currently Promethean handles all maintenance, but when they reach a larger scale they will train buyers to do maintenance.
  • Promethean is also considering selling add-ons to their systems so that buyers can also sell refrigerated products at the milk centers, such as ice cream and soft drinks, or alternatively keep other items cool such as vaccines.
  • Promethean is currently in discussions with a German manufacturer, GEA Farm Technologies, which has expressed interest in a distribution deal beyond India
  • Promethean has received a letter of intent from Amul, India’s largest dairy cooperative.


Revenue & Affordability

  • Dairy Processors are the only actors with the capital to invest $4,000 in a machine.
  • Promethean is hoping that if it can reduce its product cost it might be able to market to collection centers as well.
  • Promethean has not yet had to deal with banks providing financing for units, as its partner distributors are able to pay upfront.



  • Promethean was initially financed with the winnings from a business plan competition.
  • In 2009 they received venture capital funding, and are currently seeking a second round.


Impact Monitoring

  • Promethean does its own monitoring of efficiency and environmental impact, because they believe that the benefits of showing the system’s capabilities could be greater than just sales success. (potential for selling to other industries, or to small scale dairies in the US looking to save electricity).

More Resources

Online Resources

Contact Information

Promethean Power Systems
c/o Greentown Labs Incubator
337 Summer Street
Boston, MA 02210

( +1 617 512 8811