As more and more people leave their rural homes for high-rise buildings, 'vertical farming' may offer a way to feed the populations of future mega-cities.
Perhaps unsurprisingly, one of the first things you notice when visiting rooftop farm projects in New York City is how many steps you have to climb. After eight flights I emerge onto the sun-drenched rooftop out of breath and sweating, but it’s worth the effort. Aside from a fantastic view of the NYC skyline, dominated by the Empire State Building, it feels like I’ve stepped onto the set of a science fiction movie. I’m at the top of a building in the West Village that, six storeys below, houses the Bell Book & Candle restaurant. The small flat roof is studded with around 60 pristine white towers, each about a metre and a half high. Some are bare, just sparse white plastic shafts dotted with holes, while the others are - like strange robotic trees - in full bloom. Basil, lettuce, tomatoes - even watermelons and cantaloupe - burst forth from holes in the towers. Despite the strange artificiality of the scene, and the unforgiving, unshaded sun, it’s surprisingly tranquil up here, as the distant sounds of the city below are gently drowned out by the unending running water that circulates through the hydroponic towers.
According the United Nations, by 2050 66 per cent of the world’s population will be living in urban areas, with many of them in mega-cities such as New York. As new cities rise and old ones continue to sprawl across the landscape, both sucking in populations from traditionally rural landscapes, one question is unavoidable: who will feed these exploding urban populations? With the countryside under constant pressure, groups in cities across the globe - from community projects to big businesses - are looking to new technologies and new spaces to try and find an answer.
Bell Book & Candle’s rooftop set-up is certainly at the lower end of the scale, but being able to provide two-thirds of all the vegetables and herbs for a busy NYC restaurant’s kitchen is in itself no mean feat. The team’s hydroponic towers - they prefer to use the term ‘aeroponics’- are a soilless growing system. Instead the crops are grown in ‘liquid soil’, with the nutrients for the plants being delivered by water. BB&C says that this approach uses 90 per cent less land and up to 95 per cent less water than traditional farming, and it also yields remarkable results, with plants growing far quicker than in soil. Lettuce is said to grow 25 per cent faster, and an astonishing 1000 cucumbers are harvested a month.
About 5km uptown, on the roof of a Methodist church, the Hell’s Kitchen Farm Project has taken a much more low-tech approach to the use of a small roofspace. Despite its even more imposing urban setting, with the church roof dwarfed by towering apartment blocks and mirrored skyscrapers, the farm feels substantially less futuristic than BB&C. Gone are the robotic-looking aeroponic towers, replaced by children’s paddling pools filled with soil. It’s a decidedly more thrown-together, do-it-yourself approach, but then the volunteer-led project is about community engagement rather than turning a profit.
“Hell’s Kitchen has that history of being a very low-income, poor neighbourhood,” explains the project’s Ashleigh Eubanks as she shows me around. “We have a lot of homeless folks here. It’s a food desert. There aren’t a lot of places that have affordable vegetables.” Everything that’s grown on the roof goes to the church’s food pantry (similar to what is called a food bank in the UK), and distributed to those in the community who can’t afford to buy fresh vegetables - a very real and serious issue in a mega-city like New York, where industrially processed food is often much cheaper than fresh produce. And educating the local community about the difference between the two is as much of a priority for the project as the food itself.
“The church has after-school programming with kids from kindergarten right up through high school,” Eubanks explains. “We’re doing a lot of food education, because a lot of city kids don’t know what vegetables look like before they get to grocery stores. They don’t have access to them. That’s work that’s really important to us. We could be a model for other folks to be creative and use their roof space, to use things like kiddie pools. Even at home, this could be replicated on your personal roof, or it could be replicated on maybe a fire escape or something like that. [We want people to] have a better connection with the food that they’re growing.”
One thing that connects both the Hell’s Kitchen project and BB&C’s operations, despite their relatively small scale, is their impermanency. Both are highly seasonal, meaning that when New York’s famously harsh winter rolls around, with its heavy snowfall, both set-ups need to be dismantled and packed away.
Exciting as these small projects are, they lack something as long-term solutions to feeding future urban populations. There are, however, a growing number of academics, engineers and high-tech start-ups hoping to make the large-scale production of fresh fruit and vegetables a permanent part of urban infrastructure.
One of the companies leading the way with a more permanent approach to rooftop farming is Montreal’s Lufa Farms. In 2011, it built the world’s first commercial rooftop greenhouse, from which 120 tonnes of produce is harvested each year. The firm’s long-term plans are even more ambitious.
“The world’s population is growing and urbanising; we believe urban farming is part of the solution to feeding the planet,” explains Lufa’s Lauren Rathmell. “In addition, we want to disrupt the industrialised food system and provide fresh, safe food directly to individuals while reconnecting them with where their food comes from. Not to mention repurposing industrial spaces for sustainable food production.”
For urban farming to be economically and ecologically sustainable, hydroponic greenhouse systems have the greatest advantage in terms of productivity per square metre, year-round operations, cost-effectiveness and footprint, Rathmell adds. “[We use] pretty standard hydroponic systems, including NFT (nutrient film technique: a system where a shallow stream of water containing all the dissolved nutrients required for growth is re-circulated past the bare roots of the plants) and drip-?irrigated systems. We also have vertical growing systems in the greenhouse for producing baby greens, with LED lighting between the levels.”
It’s this ‘vertical farming’ approach that may produce a more serious - if radical - answer to large-scale urban farming. Put simply, it’s the agricultural equivalent of the high-rise building; farms stacked on top of each other in the same way cities stack homes and workplaces on top of themselves. Dickson Despommier, a professor at Columbia University and an author of a book on the topic, coined the term in the 1990s. “In a course I taught, medical ecology, the students wanted to work on roof-top gardening to see how many New Yorkers they could feed,” he tells me. “The answer was two per cent. They got depressed. I said, why not fill up the building with food production?”
Despommier’s approach introduces substantial engineering issues; mass-producing crops in hermetically sealed skyscrapers requires large amounts of energy, water, and other resources. It hasn’t deterred companies from trying to get projects off the ground though. In Japan, firms such as Panasonic and Toshiba are already conducting research, and in the US, Green Spirit Farms has vertical farming projects in operation in Michigan and Ohio.
“We have created a dynamic indoor environment which is simple, predictable and uses less water, less space and less labour than traditional farming to get the same yields,” says Green Spirit Farms’ founder Milan Kluko. “We maximise plant density, growing 15-40 plants per square foot, using 96 per cent less space and 98 per cent less water, and growing at night using off-peak energy.”
Green Spirit Farms also use very little heating or cooling, he adds, since they create micro environments on each level for the plants. “And as lighting technology has changed, we can easily adapt our systems. Creating an environment for the plants to thrive in allows us to develop our ‘farm floor’ into an integrated area of vegetables grown in harmony, and we grow several different types of lettuces together in a gourmet mix, kale, spinach, basil, radishes, rainbow chard, beets, as well as bok choy.”
Feeding a city
Talking to Kluko, it’s obvious he’s highly passionate about vertical farming’s future, but even with his bold claims, the question still needs to be asked: can a wholly urban environment like a mega-city feed itself?
Surprisingly, despite being seen as an evangelist for high-tech urban farming, Despommier isn’t so sure when I ask him. “I don’t think so, but if they were to supply just 10 per cent, and if every city did that, then we could restore some 350,000 square miles of hardwood forest and slow down climate change rates,” he points out.
Lufa’s Rathmell is much more optimistic, even with her company’s rooftop approach. “For fresh veggies, for sure. We feed 0.2 per cent of Montreal’s population currently, with two greenhouses (total 75,000 sq ft) and dozens of local partners. It takes an estimated 15 sq ft [1.4m2] to provide all the fresh vegetable needs for an individual year-round - so it would actually only take the rooftops of about 15 shopping centres to feed all of Montreal.”
Whatever the answer, for Kluko, urban farming is an essential trend that’s gaining enough momentum that it can’t be stopped. “We started this three years ago and three years from today I do not think we’ll be so unique. We need to evaluate our existing agricultural supply chain and know that we can make a difference.
“However, if we don’t start moving a bit faster in the ‘local direction,’ the cost to feed our families as well as the ability to supply fresh produce may have an inverse relationship that we cannot afford. We may look back to 2015 as the year of the ‘perfect storm of events’ and the opportunity to plant for the future.”