Thirty-three metres below London’s Clapham High Street is the world’s first underground farm. It’s shaping the future of urban farming.
Stacked racks of fresh green leaves thrive under banks of LED lights, pea shoots, basil, coriander, parsley, salad rocket, pink radish, mustard plants – the fragrance of the ‘microgreens’ filling a former World War Two air-raid shelter under south London.
A post-war plan to join the tunnels to the London Underground system never happened and, in 2015, the deserted subterranean space sprouted new life when co-founders Richard Ballard and Steve Dring decided it was a perfect site to grow food while cutting the amount of CO2 used in transport and supply.
“Growing Underground is a farm that feeds the city from within the city,” explains Ballard. “We sow, pack and grow on site, taking the harvest to New Covent Garden Market less than a mile away for distribution across the capital, reducing food miles, pollution and food waste.”
Zero-carbon food is at the core of the Growing Underground vision – which means paying close attention to what happens to the plants below ground as well as above ground.
Down in the tunnels, a team of engineers and data specialists has been helping the farmers to optimise crop performance and reduce energy use. They are led by Dr Ruchi Choudhary from the Centre for Smart Infrastructure and Construction at the University of Cambridge and the Data-centric Engineering Programme at the Alan Turing Institute.
Together, they’ve reduced the time it takes to grow some crops by 50% and all crops by an average of 7%, and increased yields by 24%. Meanwhile, the crops are grown using less space and water than conventional greenhouse growing, no pesticides and 100% renewable energy. This can only happen if every element of the farming process is carefully measured and tweaked and measured again. The plants on this farm get exactly what they need at every moment of every day thanks to the power of data – and a ‘digital twin’ looking out for its sibling from a laboratory in Cambridge.
Light, water, heat, data
“Whenever we saw an opportunity to mash two potatoes with one fork, we did it. We want to be sustainable at every stage of the process. Optimising crop performance for the energy we used seemed an obvious step forward,” says Ballard.
“The collaboration with Cambridge has been hugely beneficial in this. ‘Smart farming’ was a new area for us and we were one of the first people to do it in this way – so having Cambridge really pushing forward on the data side really sold us on the benefits of capturing and using information to solve some of the sustainability challenges we faced.”
Four years ago, Melanie Jans-Singh from Cambridge’s Department of Engineering began installing sensors in the tunnels to capture everything you might ever want to know about how this garden grows. Back in Cambridge, she and colleagues set about building a digital twin.
“From day one, Richard and Steve bet on data to help them, and we’ve assisted them from the start of their data journey,” explains the PhD student. “We learned about their farm at the same time as they did.”
Digital twin
There are 25 sensors measuring 89 variables transmitting to eight Raspberry Pi loggers in the tunnels. The data is warehoused on a server in Cambridge and sent over WiFi to an online horticultural data platform.
Nutrients, water, lights, heat, CO2, airflow, humidity. Even crop growth is tracked minutely by the farm operators. All of this is measured and compared with how the crops perform and then represented in a virtual 3D representation of what’s happening on the ground.
“This virtual representation is the digital twin,” she explains. “What the digital twin shows is better than being in the tunnel in person – it can monitor, learn, feedback, and forecast information that will make the real-life twin work better.”
At the same time, Cambridge research associate Rebecca Ward set about analysing the ‘physics of the farm’ – everything from the transfer of heat through the tunnel to the way plants use it to transpire, releasing water through their leaves by evaporation.
“A model based on data can only inform on what the data shows,” explains Ward. “But we wanted the digital twin to cope with unexpected conditions that had never been encountered before – like a very hot day outside. We’ve accomplished this by linking the data to a model based on the laws of physics.”
For more information:
University of Cambridge
www.cam.ac.uk