The system can be powered by wind or solar energy, as well as electricity
A new vertical method for growing crops which claims to use less land and only 5% of the water usually needed is being piloted at a Devon zoo.
The system grows plants in trays of water moving on a conveyor belt.
The company behind it, Valcent, based in Launceston, Cornwall, said it was a sustainable solution to the world's "rapidly-diminishing resources."
Paignton Zoo is planning to use it to grow herbs, leaf vegetables and fruit as food for its animals.
The hydroponic system rotates the plants on a conveyor belt via a "feeding station" to create airflow and stimulate growth.
According to Chris Bradford, managing director of Valcent, a 100sq-metre machine, like the one installed at Paignton Zoo, can grow up to 11,200 plants, which, he says, is 20 times more than could be grown conventionally in a field covering the same area.
He said: "The world population is growing, food supply is shrinking, water supplies are becoming more limited, food production is competing for land with housing and the production of fuel crops. We have to make better use of available land."
The zoo is growing crops to feed the animals
The system is designed to be "eco-friendly" using solar power or wind energy, with the water used to grow the plants being recycled.
"It doesn't require a green field site so it can be used in urban areas, in warehouses and in deserts," Mr Bradford explained.
Kevin Frediani, Paignton zoo's curator of plants and gardens, said: "We can grow more plants in less room using less water and less energy.
"It will help to reduce food miles and bring down our annual bill for animal feed, which is currently in excess of £200,000 a year."
Jules Pretty, Professor of Environment & Society at the University of Essex, said the vertical crop system seemed like a "welcome innovation" but was still a "relatively high energy user."
"This could be especially helpful in urban areas, but is unlikely to be applied in remote rural communities of developing countries where many problems of hunger remain," he added.