This article is from the bbc
Vertical crop system is piloted
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.
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