It's tough being a dairy farmer in Uganda, and refrigeration is hard to come by, which means lots of spoiled milk. William Kisaalita is combatting the problem with a new invention - a dung-powered milk chiller:

Kisaalita and his students began building a small-scale milk chiller that could hold 20 litres of the white stuff. Traditionally, big dairy machines have an outer and inner tank, with insulation in the space between. Compressors, condensers and refrigerants are pumped through the system to rapidly chill the milk and keep it cool. It’s a system that requires a constant electrical power, either from the grid or from a diesel generator back-up.

Initially, Kisaalita toyed with the idea of a solar powered device, but it was too expensive. So, instead, they turned to another product that cows produce in abundance. "A small farmer with five cows produces a lot of dung," says Kisaalita. "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."

Read the full article here

Ugandan Ankole-Watusi cow by The Dilly Lama