Growing plants in underground tunnels

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An innovative and award-winning urban farming facility is creating energy-efficient growing conditions in tunnels 120 feet below the busy streets of Clapham in London. Micro greens and salad leaves are thriving with the help of a smart monitoring programme that records temperature, humidity and CO2 levels.

  • Previously dormant tunnels, 120 feet below the streets of London, create energy-efficient growing conditions to sustainably produce the pesticide-free crop
  • Wireless sensors and web cams monitor temperature, humidity, CO2, air velocity and light
  • While the focus is on urban farming the team are looking to repurpose spaces rather than use new buildings

Growing Underground, an award-winning urban farming facility, is working with researchers from the EPSRC-supported Cambridge Centre for Smart Infrastructure and Construction (CSIC) to grow micro greens and salad leaves in former WW2 air-raid shelters 120 feet below the streets of London.

The two tunnels, which are on different levels and have a total area of 65,000 square feet, are leased from Transport for London having laid dormant for 60 years. Fed by hydroponic systems, they create energy-efficient growing conditions to sustainably produce the pesticide-free crop. The plants are thriving with the help of a smart monitoring programme developed by the CSIC team that records temperature, humidity and CO2 levels.

The team, led by CSIC Co-Investigator, Dr Ruchi Choudhary, installed wireless sensors and web cams that monitor temperature, humidity, CO2, air velocity and light in a section of the tunnel used for growing crops. More sensors were added in the summer to help to maintain a constant tunnel temperature of between 20-25 degrees Centigrade. Most sensors need cables, but the CSIC team’s sensors are wireless and are designed to cope with the humidity underground.

The aim of Growing Underground is to bring edible crop production to the heart of the city while minimising the carbon impact of food transportation. The verdant trays of fennel, garlic chives, pea shoots and coriander, among others, can be picked and on a plate in a restaurant within hours. The forward-thinking company, which sells its greens through Ocado and Marks & Spencer and aims to be carbon neutral, has just been awarded the BBC Future Food Award.

While the team’s focus is on urban farming they are looking to repurpose spaces rather than use new buildings; these could be tunnels or rooftops that are not currently being used.

Ventilation is the chief energy consumer at the Growing Underground project and real-time monitoring data has enabled adjustments that have cut consumption for ventilation without affecting yield.

The partially crowd-funded company is able to access the data 24/7, creating a ‘lifetime performance passport’ which provides the asset owners, present and future, with a rich source of information.

Richard Ballard, co-founder of Growing Underground, who discovered the tunnels when he was a film student scouting for locations, says: “We have been very lucky to partner with the University of Cambridge. Ruchi and her team have really helped us monitor and develop the space, which will enable us to eventually get the optimum growing environment.

“They have provided us with monthly reports which have allowed us to make adjustments to improve temperature, humidity and air velocity, and now we are working together to improve CO2 levels through enrichment.”

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The collaboration between business and academia benefits all stakeholders. Growing Underground is providing the case study for further research and the academics are providing data that will help the crops, and the company, to flourish.

The EECi team visit the Growing Underground tunnels once a month to check the instrumentation, report back to Richard and Steven and, occasionally, enjoy the fruits of their labour.

Melanie Jans-Singh, a PhD student at the EPSRC Centre for Doctoral Training in Future Infrastructure and Built Environment, spent six months installing the sensors. She says: “We are using this case study to create a baseline simulation tool for integrating urban farming into unused urban space...

“We will consider how we can integrate co-benefits between plants and buildings. When a building has heating there is a lot of waste heat produced. The waste heat (and perhaps also CO2) can be harnessed for a productive purpose.

“In addition, Rebecca Ward, a research associate on the project, has developed a finite element model that can quantify heat and mass transfer between plants and environment.

“Once we understand the synergies through our simulation model, any city can be considered in this way.”

Photography: Christopher Rudquist