Several developments in recent months suggest that 2016 will be the year that urban growing completes the leap from laboratory-scale investigation to large-scale commercial production. Next week, for example, will see the formal launch of a vast glasshouse and aquaponics project on the roof of a disused factory in The Hague.
Billed as Europe’s largest commercial urban farm, UrbanFarmers De Schilde has cost €2.5m (£2m) and boasts 1,200sq m of protected salad-growing space, intended to produce 45 tonnes of vegetables and 19 tonnes of fish per year. It will provide this directly to local restaurants as well as residents.
UrbanFarmers Benelux managing director, Scotsman Mark Durno, says: "I will be very happy to reach 900 customers a week. In the next five or even 15 years, this will be a niche of the niche. But it links into the circular economy — we have empty rooftops and empty industrial buildings. In The Hague, 25 per cent of buildings are empty. Let’s fill them with produce."
Neighbouring Belgium intends to go one better later this year with the opening of Foodmet, a rooftop aquaponic and 1,800sq m greenhouse development on the roof of a wholesale food market and slaughterhouse in Brussels.
Backers of the Abattoir project intend a further four such projects for the greater Brussels region "to offer complementary local products and supply a significant amount of fresh fish and produce to the city".
Already this year, what is claimed to be Europe’s largest automated urban farm opened in the town of Waregem in western Belgium. Unlike the two rooftop facilities, this is enclosed, with eight growing layers occupying 90sq m, giving a total growing space of 240sq m.
Although intended to test new crops and techniques rather than meant for commercial production, it has been conceived by its developer Urban Crops as a shop window for future commercial facilities, according to managing director Maarten Vandecruys.
Tailored lighting systems
A major factor making such closed growing systems more commercially viable is the ongoing development of LED lighting systems tailored to the requirements of horticulture. "LEDs are more efficient than normal lamps and offer the advantage of being optimised to produce specific wavelengths," says Lincoln Institute of Agri Food Technology director Simon Pearson.
"In addition, wavelengths can be altered during the day to give optimum day length, and a large amount of light can be created instantly." He adds: "The falling costs of LEDs and greater uptake from industry mean we are approaching the tipping point where alternative approaches to cultivation may be possible."
Picking up on the trend, Europe’s largest horticultural technology show, GreenTech in Amsterdam
(14-16 June), will kick off with a day-long "vertical farming conference" together with the first international design award for vertical farming. The show will also host an indoor farming pavilion for the first time.
These are being organised by the Germany-based non-profit Association for Vertical Farming, which has seen its international membership double over the past year. "It’s exciting to see how this industry is growing faster than we had ever anticipated," says its board vice-chair Maximilian Lössl. "A lot of young people and entrepreneurs are changing their career paths to start vertical farming companies recently. Most of the current vertical farms going up around the world are actually looking for growers to hire."
The idea "is not just hype any more", he insists. "Vertical farming will be mainstream in 10 years, meaning every big city will have a least one vertical farming [unit]."
London is already home to two such units. Conventional vegetable supplier G’s Fresh has invested in Clapham’s Growing Underground, where fresh salads are grown in a closed hydroponic system housed in a disused Second World War air-raid shelter. G’s Fresh managing director Daniel Cross explains: "Disused buildings above ground in London are too expensive or require too much capital to be commercially viable. Comparatively, tunnels are attractive due to their lower cost per square metre and their closeness to market and population."
However, a former warehouse in Beckton, east London, now houses GrowUp Urban Farms, a social enterprise that combines vertical growing with aquaponics to produce salads, herbs and tilapia fish for local sale. It began trading last autumn and its first fish went on sale earlier this year.
"The next one we open, we’re hoping to make it 10 times the size and use that as a benchmark for future farms," says co-founder Kate Hofman. "The thing about warehouses is that they’re everywhere." GrowUp already has a smaller-scale aquaponic unit known as the GrowUp Box housed in an "up-cycled" shipping container, financed through a crowdfunding bid that drew 300 supporters. It is now looking for partners to replicate this as a "community engagement project" elsewhere.
With a similar social and environmental ethos, Grow Bristol has just begun aquaculture production from its units in the city’s Temple Quarter, again housed in old shipping containers. Co-founder Dermot O’Regan points out that ethics aside, projects such as his have the edge on product quality.
"Things like salad and herbs lose their nutritional benefit as soon as they’re harvested," he says. "Even if they’re grown in greenhouses in the UK, they travel a long way. What we’re offering is harvested the same day as it’s on your table."
Again combining the arguments of sustainability and freshness, France-based chain AccorHotels announced last month that it would create 1,000 vegetable gardens in its hotels by 2020 as it aims to cut food waste by 30 per cent.
On an even grander — some might say outlandish — scale, London-based "starchitect" practice Rogers Stirk Harbour + Partners has designed a free-standing aquaponics tower named Skyfarm "as a research project". The multistorey "hyperboloid" (vase-shaped) structure is made of bamboo to create a rigid circular frame and maximise sun exposure, and is zoned to spread the weight of water efficiently across the tower.
As well as housing the hydroponic growing of crops, it is also designed to employ aeroponics, in which plants are grown in a misty environment using minimal water and no soil.
"The form of the tower enables it to be easily scaled," says the practice. "A 10m version could be constructed in a school, or an 80m farm built in a larger urban area." It adds: "While the upfront costs of Skyfarm are higher than standard industrial-scale agriculture, the ability to grow produce with a short shelf life — such as strawberries, spinach and lettuce — around the year and close to market without costly airfreighting makes it an attractive, sustainable proposition."
However, last month Rheims University professor of urban planning and sustainability Francois Mancebo attacked what he called "skyscrapers camouflaged in green", which, he said, "under the disguise of promoting agriculture in the city promote practices that are absolutely unsustainable".
Mancebo, who is also director of the International Research Center on Sustainability and the Institute of Regional Development & Sustainable Urban Planning, claimed that the energy cost of using LED lighting systems, controlling humidity, temperature and air circulation, as well as the input of fertilisers and pesticides, "is all but sustainable and can certainly not foster urban sustainability".
Feeding astronauts on missions to Mars
Philips Lighting has collaborated with the University of Arizona Controlled Environment Agriculture Center (CEAC) to test energy-efficient ways of growing food to feed astronauts on missions to the moon, Mars and beyond.
A recent nine-week study in a prototype lunar greenhouse found that lettuce grown under Philips LED modules achieved up to 54g/kWh of fresh weight, compared with 24g/kWh of fresh weight under a high-pressure sodium system.
CEAC director Dr Gene Giacomelli says: "Findings from this study are critical in that not only can they be applied to growing food in space but to farming techniques where there is a shortage of water and good agricultural land right here on this planet."
The Philips GreenPower LED toplighting was programmed with a bespoke light recipe based on light spectrum, intensity and distance from the crop. This was intended to promote specific plant characteristics including compactness, colour intensity and branch development.
NASA has been working with universities for more than 25 years to research how LEDs can support plant growth in closed environments, with the products of this being used in the space shuttle and the International Space Station as well as its ground-based Habitat Demonstration Unit, according to NASA plant physiologist Ray Wheeler.
He adds: "It is fascinating to see how LED plant lighting has expanded so rapidly around the world and continues to further develop as we have seen most recently with the Mars-Lunar Greenhouse Project."