How can you keep your food fresh and your drinking water cool in a hot third world country? The pot-fridge is the latest in a range of savvy inventions for the poor in the developing world. An idea revived by NGOs working in Africa, this nifty invention is now being used by farmers and their families in warm climates to preserve their food and keep the insects away. This desert cooler does not require electricity or any power source, apparently making it ideal for poor rural villages and sustainable living fans. According to the NGOs, a pot-fridge will keep your tomatoes fresh for almost three weeks and all it takes is some sand, water and two pots. Is it time to give up on ‘white goods’ and get earthy? The programme shows us how to make one.