Warm milk spoils—and millions of the world's energy-poor rural farmers have no way to keep it cool.
If only the bovine digestive system also produced some sort of vast and seemingly endless flow of energy-rich sludge.
It does: The dung-powered milk chiller just might be an idea whose time has come.
Developed at the University of Georgia by Uganda-born engineer William Kisaalita and his students, the chiller also runs on propane. But it's the dream of dung energy, which apparently becomes economical only if it's used around the farm in other ways, that gets Kisaalita's juices flowing.
"A small farmer with five cows produces a lot of dung," Kisaalita told Public Radio International for a report last week on the latest milk-chilling technologies. "You can ferment the dung, and use a fraction of the bio-gas to run the milk chiller. The rest could be used for cooking or lighting."
Kisaalita's team is working on a 70-liter chiller that could sell for $300 on a "rent to own" model. The prize: cold milk—and a way for dairy farmers to sell their stash only when the time is right.
"The small farmer could milk her cows in the evening, chill it, and then add more milk in the morning," Kisaalita said. "Then she could wait for the buyer who will give her the best price, because she's not in a hurry to sell. She's now empowered, because she knows the milk won't go bad."
Check out PRI's full report for more of the many solutions being developed to the ancient problem of warm milk, and this Pacific Standard profile of Kisaalita for a closer look at his work.