Row upon row of leafy vegetables are stacked one above the other, stretching into the distance as far as the eye can see, all inside a huge shed, under bright artificial lights.
This is the new frontier of agriculture: vertical farming, a system that, proponents say, makes best use of land and water for high-value crop production.
From an old steel warehouse in Newark in the United States to a Second World War tunnel beneath London, vertical farming and its bright artificial lights offer a stark contrast to the traditional earthy image of crops growing in fields.
The UAE is becoming a key centre for the phenomenon, with the news this week that the catering arm of Emirates Airline has partnered with a Californian company, Crop One, to develop what has been described as the world's largest vertical farm.
In a country that depends on imports for at least four fifths of its food, it offers the prospect of growing more produce locally – albeit in this case for aircraft and airport lounges, rather than homes and restaurants – while making best use of precious water resources.
Vertical farming is based on the use of hydroponics, in which plants are grown using nutrient media instead of soil, a technique first used in the UAE almost half a century ago and now well established locally through a number of commercial farms.
Emirates Hydroponics Farms, for example, based between Abu Dhabi and Dubai, can produce one kilogram of lettuce using about 20 litres of water, with water being recycled instead of draining into the soil; standard farming methods might require 400 litres, an astonishing amount for any country, particularly a water-scarce one.
By controlling variables such as temperature, nutrient levels and humidity, growth rates are increased significantly, so 18 crops per year can be produced – three times the number of standard agriculture.
The absence of soil – with hydroponics, plants grow in media such as rock wool, a fibrous substance produced from molten rock – eliminates soil-borne diseases.
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Temperature can be controlled by air conditioning, allowing year-round production even in the UAE, or evaporative cooling.
Typically, hydroponics is used for leafy crops such as salad rocket and lettuce, along with vine crops – among them peppers, cucumbers and tomatoes. In the UAE, it has been used to grow even rice, papayas, oranges and grapes, albeit on a small scale.
In taking hydroponics and employing it on multiple levels, instead of sunlight, vertical farming uses LED lights tailored to the requirements of the particular crop. Artificial lights allow farms to be located anywhere, including in urban environments.
“There's a growing awareness that you can use hydroponics and you can use spaces that would otherwise not have a purpose, like these disused tunnels [under London where a vertical farm is located]. Vertical farms are quite topical because they don't use much space,” said Professor Neil Bricklebank, who has worked on hydroponics technology at Sheffield Hallam University in the UK.
Improvements in LED light technology have been credited with helping to promote vertical farming: artificial illumination can generate all the light that a plant needs, and the latest types can be located just a short distance above the crop, allowing for the stacking of layers. LED lights are also becoming more efficient, cutting energy costs.
As reported by The National, the newly announced US$40 million (Dh146.9 million) Emirates Flight Catering facility will be located at Dubai World Central near Al Maktoum Airport and will produce 2,700kg of leafy greens per day without pesticides or herbicides. It will cover 130,000 square feet or about 1.2 hectares – but it is claimed that it will grow as much produce as a 364-hectare farm.
The announcement of the new farm, construction of which is set to begin in November, comes not long after the official opening in Dubai of what has been described as the GCC's first commercial vertical farm. This 8,500-square-feet facility in Al Quoz Industrial Area 1 was developed by Badia Farms and began producing leafy green vegetables in December last year, before a ceremonial launch in March.
On a smaller scale, through other operators, vertical farming has been carried out in the UAE since at least 2012.
New patented technologies are being promoted for use in vertical farms. The US-based AeroFarms, for example, which created the vertical farm in the former steel facility in Newark, describes its method as “aeroponic”, with roots receiving water, nutrients and oxygen in a mist instead of liquid. This is said to use 40 per cent less water than hydroponics.
Although now found in countries including Japan, South Korea and the Netherlands, vertical farming has, until now, had several disadvantages, according to one specialist.
Dr Howard Resh, a Canada-based consultant who has been involved with hydroponics projects in Saudi Arabia and Kuwait, among other places, says that vertical farms can be “extremely costly to construct and operate”, partly because of significant wage costs.
Also, energy inputs are high thanks to lighting and temperature controls, although local vertical production can reduce carbon emissions from transporting foodstuffs.
Dr Resh argues that the lighting in some vertical systems is not as good as in greenhouses, producing poorer-quality crops. However, he also sees positives.
“These vertical systems may have an advantage in a hot, humid climate where greenhouse cooling cannot maintain temperatures at optimum levels. In an insulated building, these temperatures could be better regulated with air conditioning systems,” said Dr Resh, who is involved with a new vertical system that can be fully automated without the need for harvesting, because the plant is sold in the growing container.
“It has the potential for being economically feasible for growing lettuce, leafy greens and herbs,” he said of his vertical farming method.