Growing Underground, a company based in Clapham, sustainably grows salads and other "microgreens" 33m below the busy streets of London.
Using the latest hydroponic systems and LED technology, the crops are grown year-round in a "perfect, pesticide-free environment."
"The limitations at the moment are the cost of energy, predominantly, as well as labour, which is our second biggest cost, said co-founder, Richard Ballard.
"But we're going to see in the next 20 to 30 years, with artificial intelligence and robotics, the labour being taken out of this at different levels.
"If you'd asked somebody 40 years ago about free information, they'd have laughed. We have free information today with the internet. So free energy is probably the next step."