This is the Â£50,000 winner of a contest to find the world’s greenest invention – a solar-powered oven made from cardboard.
The cooker took the FT Climate Change Challenge crown after beating 300 other creations, including a food additive which stops cows passing wind.
The Kyoto Box oven – which costs just Â£3.50 to make – can cook casseroles, boil water and bake bread.
It is made from 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.