Growing crops indoors with no natural light, using sophisticated monitoring and control equipment could have a key role in producing more food in areas where land is limited.
Consumers in Japan and North America have long accepted the use of technology to produce fruit and vegetables, provided their quality is good. And this view is now gaining ground in Europe, and a growing number of city farms are adopting vertical farming.
The technology is becoming more commercially viable, with low-energy LEDs and climate control systems relieving farms of their dependence on the weather. Retailers discovered this to their cost at the beginning of this year, when deliveries from southern Europe were almost halted by extreme cold.
Climate cells control every aspect of the growing process, making it possible to farm anywhere in the world. But will zero-daylight farming ever replace fields and greenhouses? And sunlight is free, so how can you exclude it and still offer an affordable product?
“Climate-cell cultivation is healthier, more predictable, and delivers a better product,” says Gus van der Feltz. He is the director of Philips Lighting’s Growwise Centre, and head of the city farming team at High Tech Campus, Eindhoven.
As a LED lighting manufacturer, Philips is a leading force in the development of daylight-free farming. The Growwise Center was founded in 2015 to research and improve vertical farming, working closely with companies in the industry such as Priva and BrightBox, and with students of the University of Applied Science in Den Bosch, the Netherlands.
It develops lighting, nutrient, carbon dioxide and cultivation systems for leafy crops and herbs, and carries out feasibility studies. “A lettuce grown this way still costs twice as much as with conventional technology,” Mr van der Feltz says. This is mainly down to capital costs and energy.
The investment cost of a vertical farm is between $1,700 and $2,800/sq m ($158 and $260/sq ft), depending on its scale and degree of automation, but because it makes better use of space and the crops grow quickly, yields are very high. “You can get more than 100kg/sq m (20lb/sq ft) of lettuce a year, which is up to twice as much as in a greenhouse.”
Vertically farmed crops are of better quality than the traditional variety. Sophisticated lighting systems significantly improve their taste and robustness, and their nutrient intake can also be controlled. They last longer and contain no residues or other undesirable substances, and the technology scores highly in the sustainability stakes.
According to a report by the Unesco-IHE Institute for Water Education, 1kg (2.2lb) of lettuce uses just 1.5 litres (0.4gal) of water compared with 7.5 litres (2gal) for a Dutch greenhouse, 180 (48gal) for an outdoor farm in Spain, and 450 (120gal) in California. Also, the climate cells at the Growwise Center condense the water that evaporates from the lettuces and store it in holding tanks for irrigation.
Another big advantage is that no plant protection is required. The pressure in the hermetically sealed cells is slightly raised, and air flows over the crops, creating a healthy and fertile microclimate.
“The cells are steam cleaned between crops,” Mr van der Feltz says. “The recirculated water is passed through a UV treatment, so it doesn’t contain any chemicals either.” In terms of energy consumption, the results are less impressive. Depending on the energy source you use, the carbon footprint of a vertical farm is much worse than, say, a greenhouse.
It requires 5 times a greater area of solar panels, though this could be significantly improved by more energy-efficient lights and better cooling. Costs can be further reduced by using better cultivation and logistics systems and more suitable crop varieties.
For now, vertical farming is best suited to low-growing leafy crops, herbs and microgreens such as sprouts and babyleaf. Almost all of their biomass is saleable, unlike fruit, for example, where much of the plant is inedible. “We’ve grown strawberries here from seed to prevent disease,” Mr van der Feltz says.
“They were the most wonderful strawberries we’d ever tried, because we could use light to control their sweetness. One student tested some cucumbers: they grew fast and tasted delicious, but you can’t take the cost out of the equation.”
Vertical farming is not necessarily the solution to the world’s food problems – “You can’t feed the world with lettuce,” – but it does have its commercial attractions.
High-end leafy crops are another niche market. This year, Staay Food Group is installing climate cells at its new cutting plant in the Dutch town of Dronten. Almost 1,000sq m (10,800sq ft) in area, they will be used for eight or nine-layer cultivation of luxury salad varieties.
If the pilot is successful, the cells will be expanded to create the world’s biggest vertical farm. The test is being carried out by a consortium that also includes Philips Lighting, Rijk Zwaan, Certhon, and the local agricultural college. “This has been tested at the Growwise Center for a year and a half,” says Staay Food Group director Rien Panneman. “The concept is ready, and so is the expansion plan.”
The lettuces are used in convenience products, such as ready-made salads for Aldi. “They contain no pesticides or foreign bodies, and fewer bacteria than traditional crops. They also have a much longer shelf life. All of these are very important to Aldi.
Japan and the US – ahead of the game
Commercial vertical farming began in Japan, where consumers are used to paying a lot for their vegetables, and food safety has been an issue since the 2011 tsunami. After that happened, the Mirai group invested the equivalent of $6 in converting an empty Sony factory to produce 10,000 lettuces a day. In 2013 another Japanese company, Spread, launched its TechnoFarm, producing 770t daily.
This year, it is building a second highly automated site in Kyoto that will produce three times as much lettuce. Vertical farming is also growing relatively fast in the US. Since the product is residue free, it can be labelled as organic, and often comes with a “local for local” sticker. It is fresher and better tasting than Californian lettuce, and sells for three to four times the price.
The companies involved are small. For example, AeroFarms, in Newark, New Jersey covers 6,400sq m (69,000sq ft) while Farmbox Greens in West Seattle, Washington is just 540sq m (5,810sq ft) of microgreens). But the story of FarmedHere shows that vertical farming is still not a licence to print money.
It used to be the biggest vertical farmer in the US, cultivating 27,500sq m (296,000sq ft), but according to the Chicago Tribune, it shut down early this year after its parent company decided to focus on processing local produce.
The lettuces cost about twice as much as conventionally grown ones. “They only account for a fraction of the cost of all the ingredients, so they don’t significantly increase the price,” Mr Panneman says.
“You get ready made salads that last much longer.” The price will also fall as the project expands and uses lighting and cultivation technology more efficiently. “We expect to harvest 6,000-8,000kg (13,000-17,600lb) a week, which is only a small proportion of the total amount we process. So convenience will be the catalyst for vertical farming.”