By 2050, more than 80 per cent of the world's population will be living in ever-larger urban centres. To feed 9 billion people without consuming land, Professor Dickson Despommier of Columbia University in New York conceived the concept of the vertical farm.

Vertical farms are buildings that, instead of housing homes and offices, contain urban greenhouses. These food self-production centres can be built from scratch, like the Milan prototype Skyland by Enea for Expo Milano 2015 and Sky Greens in Singapore; they can be incorporated into urban regeneration programmes for disused spaces, as in the case of The Plant in Chicago; or they can be installed for the production of organic animal feed, as at Paignton Zoo in England.

Whatever their origin, saving, recycling and reuse are always the keywords. Vertical farms built inside existing buildings or in underground spaces also guarantee food production, all thanks to LED technology. In the absence of solar energy, or in addition to it, the growth of hydroponic crops (those that require very little water) is achieved through LED lighting powered by solar panels. Vertical farms are also the ideal solution in situations of severe air pollution, because the crops are grown in a controlled atmosphere, free of pollutants and without the use of pesticides. The result is a zero-kilometre food product of excellent quality with a very strong social impact.

These green skyscrapers were conceived as a globally sustainable solution to world hunger. However, the high construction costs have meant that vertical farms have so far served primarily as an active tool for food education and raising awareness of sustainable urban practices. The further development of this technology through low-cost systems, or simply the wider spread of hydroponic cultivation, represents a milestone for nutrition in the most at-risk countries.