Refrigerators that thrive in the sun

Electricity shortages are common in many emerging economies, often resulting in food wastage as items spoil with the rising temperatures.

While some businesses can afford to use diesel back-up generators to power their equipment, solar-powered refrigerators offer a sustainable, long term alternative that combats energy shortages and global warming.
The fridge lady of Namibia Emily Cummins (21) came up with the idea of a “sustainable” fridge that works through evaporation and can be used to keep perishable goods such as milk and meat cool for several days at a temperature of 6°C, while working on a high school project in her grandfather’s potting shed in England.After her A-levels, Cummins spent five months in Africa perfecting and demonstrating her product. She gave away the design plans in townships across southern Africa because she wanted to enable as many people as possible to build their own fridges.
Cummins, who became known as “the fridge lady” in Namibia, explains that her prototype comprises two metallic cylinders – one inside the other, between which a locally-sourced material such as sand or wool is packed tightly before being soaked with water. “When the fridge is placed in a warm environment, the sun’s energy causes the outer part to ‘sweat’ – water then evaporates from the sand or wool and heat energy is transferred away from the inner cylinder, cooling it down.”
She adds that the design is ideal for use in developing countries because it doesn’t require electricity, and can be built using barrels, spare car parts and ordinary household materials, such as wood and plastic. “Unlike previous potin-pot coolers, the contents are kept dry and hygienic because the water does not come into contact with the product,” says Cummins. “The cylindrical shape of the fridge also ensures that there are fewer areas where bacteria can build up.”
Cummins is currently developing a second generation fridge that maintains an even lower temperature and is more energy-efficient.

1. Fridge is made up of two cylinders – one inside the other – and is not connected to any power source. Outer cylinder is made of any solid material with holes drilled in the
sides.
2. Inner cylinder is made of metal and has no holes to ensure contents remain dry.
3. The gap between the inner and outer cylinder is filled with a material such as sand, wool or soil, that can be soaked with water.
4. In hot weather the sun’s rays heat this wet material and the water evaporates off. As the material is held against the inner cylinder wall, heat
is removed from the inner chamber by the evaporation process, keeping it at a cool temperature of 6°C.
5. Resoaking material with fresh water will keep the fridge “working”.
For more information, visit www.emilycummins.co.uk or email: enquiries@emilycummins.co.uk