A cheap solar cooking stove called the Kyoto Box has won the FT Climate Change Challenge – a global competition to find the best innovations to tackle climate change.

The box, which costs about five euros to make, aims to save some of the millions of children who die each year from drinking unclean water by allowing families to boil water and cut the health risks from smoke inhalation. The inventor believes it will halve the need for firewood, saving an estimated two tonnes of carbon per family per year, and sparing women from the time-consuming and sometimes dangerous job of gathering fuel.

The Kyoto Box uses the greenhouse effect to cook and can boil 10 litres of water in two hours. It consists of two boxes, one inside the other, with an acrylic cover which lets the sun’s power in and traps it. Black paint on the inner box and silver foil on the outer help concentrate the heat while a layer of straw or newspaper between the two provides insulation.

The FT Climate Change Challenge aims to seek out and showcase the most exciting innovations - practical ideas which will reduce emissions and make us more resilient to the change ahead, and which can be developed, brought to market and scaled up to achieve maximum impact.