Vertical farming

Growing spinach where the sun doesn’t shine

Once seen as a “towering lunacy”, vertical farms are all the rage from the U.S. to Europe to Asia.

When major-league consumer electronics companies like Toshiba and Fujitsu begin turning pristine microchip clean rooms into lettuce and spinach factories, something very out of the ordinary has to be going on. Where engineers in bunny suits once tended precision machines etching silicon chips, people in similar garb now nurture green vegetables in serried ranks of hydroponic racks stacked up to the ceiling. Adding to the mystery, the whole enormous room is bathed in an unnatural pink glow.

What’s going on? Welcome to the world of “vertical farming” – an emerging horticultural business model which its proponents say has the potential to provide an energy-efficient, low-carbon way to boost food security as earth’s population swells to 9 billion by 2050. The overarching idea is to allow vegetables and fruit to be grown in urban buildings no matter what sunlight is available. And because it happens indoors where regular pests cannot get at the crop, there is no need for pesticides and genetically modified crops.

The trick is to harness cool, low-energy LED lighting to mimic the important red and blue wavelengths in sunlight that makes plants grow – a light mix that lends vertical farms their telltale pinkish glow. Then, smart software is used to choreograph every aspect of plant growth, from irrigation to air quality, temperature and nutrition – allowing growth of fruit and vegetables indoors without any sunshine at all. Do that on every floor of an apartment block, or an abandoned post-industrial multi-storey factory, and you have a vertical farm that can operate in any urban environment, the theory goes.

Why do this? At issue is the fact that, conventionally, vegetables and fruit are grown either in vast fields or in massive glasshouses in rural areas where real estate is cheap and the sun can do its level best, weather permitting, to fuel photosynthesis. But rural operation means that crops have to be transported on carbon-belching trucks for consumption in cities that are often many hundreds of kilometres from where the greens or fruit are grown.

More city slickers

Feeding ourselves this way is set to hit the buffers, however, as UN figures show that a growing share of the earth’s swelling population will be moving to cities. In 1950 just 30% of the world’s population lived in urban areas, a figure that had risen to 54% by 2014. By 2050, however, 66% will live in cities – and in the developed world an eye-watering 86% of us will be city slickers.

This means current food production methods cannot go on, says Dickson Despommier, an ecologist at Columbia University in New York – and the man credited, along with his students, of coming up with the idea of vertical farms in a classroom thought experiment in 1999. Their idea aims to produce far more food as populations swell and do so nearer inside the cities where most people will be living – so crop transport carbon emissions are kept down.

“My class dreamed up a project in which they decided to find out how much food they could grow on the flat rooftops of New York City and how many people that could feed”, Despommier recalls. Their calculations proved initially disappointing. “Some had tears in their eyes when they realised they could only grow enough to feed 2% of Manhattan. They felt they had failed miserably at doing some good. But I thought their idea could work if they moved the growing units indoors and ran it on, say, six floors of a building, and so feed 12% of Manhattan. That amazed them.”

That happened to be on the students’ last day of classes at Columbia and the group then broke up – but Despommier has developed the idea further, publishing a book called The Vertical Farm: Feeding The World In The 21st Century and he has toured the world advising investors and entrepreneurs on how it can be done.

Dome-shaped greenhouse in Japan

One of eight dome-shaped hydroponic vegetable plants built in an area damaged by the tsunami that hit Japan in 2011. Inside each dome is a 20-m-diameter water tank that holds lettuce seedlings. As the tank rotates, the growing heads of lettuce gradually slide toward the outermost circle, where 3,600 are harvested every day.

Hyper-clean factories

And it is indeed being done, big time, from the U.S. to Europe, India, Japan and many points in between. “In Japan there are now hundreds of examples of what they are calling either vertical farms or simply plant factories,” Despommier told Technologist. Some of those are subsidiaries of electronics conglomerates that see strong similarities between the way they run automated, hyper-clean microchip and computer factories and the precision, pathogen-free way a vertical farm needs to be run.

For instance, Toshiba, the computer and TV maker, has converted a former floppy-disc drive clean room into a 2000 m2 vertical farm in Yokosuka, near Tokyo. It is growing sprouts, spinach and lettuce. In Aizu Wakamatsu, in Fukushima prefecture, computer and phone maker Fujitsu has converted a former cellphone-chip-making clean room into a salad growing farm, also of 2000 m2 area – producing 3,500 heads of lettuce per day. Fujitsu is also using cloud-computing services to distribute live farm data to its vertical farm staff, allowing them to diagnose problems remotely via smartphone apps. While that’s impressive enough, the potential for vertical farms to produce an almost unfeasibly large amount of vegetables, every day of the year, is more than apparent at a company called Mirai Co in Miyagi, Japan, which has bought a former Sony chip making plant. Working closely with U.S.-based LED maker General Electric, Mirai has built 18 ultra-long hydroponic racks that are each 15 levels high and illuminated them with no less than 17,500 LEDs. The Mirai farm trounces Fujitsu by growing an astonishing 10,000 heads of lettuce per day.

Fukushima effect

Japan is leading the charge into vertical farming, says Despommier, largely as a result of burgeoning consumer demand for untainted fruit and vegetables after the March 2011 tsunami-activated nuclear meltdown at the Fukushima Daiichi power station. That tragedy spread fears of radioactive particles in food grown outdoors that has had a knock-on effect.

Elsewhere, Singapore is getting in on the act, with a towering spinach and lettuce farm called SkyGreens making use of natural sunlight, rather than LEDs, with an eight-storey, electronically controlled glasshouse. And Panasonic of Japan has kicked off production at its first LED-lit vertical farm, in Singapore, supplying a premium restaurant chain with herbs, mustard, radishes and red lettuce.

In the U.S., vertical farming is just as vibrant a start-up business with firms like Green Sense Farms in Portage, Indiana, running the largest plant so far, but with Green Spirit Farms of New Buffalo, Michigan, expanding fast – into Ohio and West Virginia – as the economics of energy saving LEDs kick in. Indeed Despommier recently joined Green Spirit Farms’ founder, Milan Kluko, and his colleagues as they celebrated a seasonal festivity unique to vertical farming: their first “annual midwinter harvest festival”.

The challenge of integration

If such festivals are to proliferate worldwide, the LEDs making vertical farms an economic prospect need to drop in price and become still more energy efficient. LEDs have around 28% energy efficient currently – but in research they have been demonstrated at 68%. The other necessary vertical farm technologies – climate control, hydroponics, humidifiers, biosecurity measures and the supervisory computer systems that are used to control them – are all reasonably mature, but integrating them in this new way remains a challenge.

Another hope of vertical farmers is that their closed systems will keep out pests and crop diseases, as long as staff in the centres stick to strict biosecurity protocols, such as not wearing their outdoor clothes and shoes, which may carry pathogens, into the farm. A role for ultraviolet LEDs to zap bugs like Escherichia coli – spread to growing plants by unclean human hands – could one day be developed.

Such issues may not bother the big farms for long. While smaller scale vertical farms are expected to continue employing people, the larger ones, such as the Japanese electronics companies’ nascent plant factories, will probably end up fully automated, like robotically controlled warehouses – but where the robots pluck out vegetables rather than DVDs or books. “In a 10-layer crop system there is no way people can get up and down it,” says Martin McPherson, science director at Stockbridge Technology Centre (STC) in the UK. “It will have to be automated.”

For his part, Despommier sees the fact that corporate Japan is buying into vertical farms in a big way as a blow to his vociferous critics, who greeted his plans for the farms with particularly coruscating commentary, with one dubbing them “towering lunacy”.

“The critics were short sighted,” says Despommier. “What they all failed to do was allow for progress in the technology, like the increasing efficiency of the LEDs. The evidence is overwhelming that if you can identify a technological issue then engineers can solve it.”

Dickson Despommier (ecologist at Columbia University in New York), Martin McPherson (science director at Stockbridge Technology Centre (STC))