Food waste is a trillion dollar problem around the world but Denmark has managed to cut the amount of food it throws away by a quarter. Here's how it did it.

n a chilly summer’s night in the centre of Copenhagen, a crowd gathers around the entrance of a restaurant called Dalle Valle. It’s 22:30 and the dinner buffet is winding up and the kitchens are about to close. But these people, mostly in their 20s and 30s, are here for the food that the diners inside didn't want.

Dalle Valle is one of hundreds of restaurants and cafes listed in an app called Too Good To Go, which lets you order takeaway food that would otherwise be thrown away, for knock-down prices. It’s an example of many social initiatives set up in the last few years to address the growing problem of food waste. And in Denmark, they are leading the world.

Like many countries, Denmark has a problem with food waste. A 2014 government survey estimated that each household in the country throws away 105kg of food each year on average. Worth around 3,000 kroner (£350), that’s more than a month’s worth of food for most families. Shops will also discard food with minor cosmetic flaws. It is common for bakery staff to throw away rolls or loaves of bread that come out of the oven the wrong size or shape, for example.