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Vertical farming’s role in a water-secure future

  • Vertical farming’s role in water-secure future

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H2o Building Services
H2O Building Services is one of the UK’s leading providers of commercial water management and consultancy services. With unparalleled expertise in carrying out water audits, we specialise in reducing water saving businesses money on their water bills

Vertical farming does exactly what it says on the tin… it grows upwards! Quite simply, the plants are stacked vertically on pillars or shelves and grown in enclosed conditions – just like the greenhouses you’re more used to seeing, except with some key differences.

The most obvious of these is, of course, the fact that plants are grown in a vertical fashion as opposed to the more traditional horizontal way of working.

But there are other factors that come into play as well, including the use of LED lights instead of the sun and a closed-loop water recycling system. There’s also no need to use any pesticides because the plants are grown in such clean conditions.

Vertical farming is part of what is known as controlled environment agriculture, a blanket term that covers a range of different technologies and growing environments.

As business-focused membership organisation Agri-TechE explains, technologies are now being developed to automate and manage as many aspects of the growing environment as possible, everything from lighting and temperature to humidity, irrigation, harvesting and cultivation.

Vertical farming as a production system

Research has been ongoing into whether vertical farming has any viability as a food production system, with Wageningen University & Research (WUR) and the Delft University of Technology collaborating on a project investigating the benefits of this potential new way of working.

Studies show that vertical farming may well prove effective as a production system where resources like water, land or CO2 may be scarce, such as in arid or densely populated areas. It could also be beneficial if there’s a need to strengthen local food production in the face of extreme climate events, or if local areas are heavily dependent on imports.

Furthermore, studies also show that there’s potential to integrate these farms into existing energy networks so as to provide additional services, such as in places with dense populations that rely on renewable energy.

WUR researcher Luuk Graamans said: “We should not consider greenhouses and vertical farms as two diametrically opposed systems. Instead, they should be seen as on a gradient.

“Greenhouses can incorporate the technologies from vertical farms to increase climate control and to enhance their performance under specific climates. The vertical farm is the pinnacle of climate control and may serve situations where such control is warranted, or where interaction with the exterior climate is undesirable.”

He went on to say that while these plant factories are more efficient for water, land area and CO2, that’s not the case for electricity, where greenhouses are the better option because of solar energy, which is freely available.

Mr Luuk continued: “Greenhouses are generally more electricity efficient because of the freely available solar energy. Only in situations with little light and significant energy loss, or perhaps with excessive heat gain across the façade, may a vertical farm come out ahead.

“The important question is which resources you deem (in)valuable and this is closely related to the local climate, context and market.”

Vertical farming & water security

Vertical farming is able to make use of atmospheric water generation, where water is produced from humidity already in the air, filtering it so it can be collected and consumed.

This technology is both eco-friendly and cost-effective, reducing reliance on natural water resources and creating a continuous water cycle where the water produced is used to grow plants and then sent back into the internal atmosphere to be reharvested time and time again.

Given that irrigation for agriculture accounts for 70 per cent of the world’s total water use, finding more sustainable ways of working are now a must for the industry… and vertical farms could form a part of the solution to the problem of over-abstraction and overuse.

This kind of indoor farming has other benefits, as well, such as being able to grow crops all year round because consistent growing conditions are maintained, no matter what’s happening outside. Harvest times can also be reduced, while volumes increased without having to compromise on quality or flavour.

These farms are also able to be more productive on smaller land areas because of their stacking grow systems. They can be designed and built in any location, no matter what the climate is like, whereas more traditional farms need access to fertile land.

Leo Marcelis, professor of Horticulture with WUR, explained that it’s possible to grow enough vegetables for 100,000 people each eating 250g a day in a high-rise building on a surface area around the size of a football field… all while enjoying complete control over the production and removing dependence on seasons, daylight, temperatures and weather conditions.

Water use reduction is one of the biggest benefits, however, with only between two to four litres of water required to grow 1kg of tomatoes. Compare this to the 17 litres of water used in a greenhouse or the 60-200 litres required for a field in southern Europe and it seems that vertical farming could make a significant difference to water availability.

One potential disadvantage could be the relatively high energy consumption associated with these farms. LED lamps are economical, yes, but a quarter of all costs goes towards energy consumption, Mr Marcelis confirmed… although work is now underway to see how usage and costs could be reduced.

It’s all about making sure the light is being used more efficiently by the plants, he added, which will involve optimising temperature, water availability, fertilisers, humidity and CO2 concentration, as well as working out the optimum colour and intensity of the light throughout the day.

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