The UN predicts the world’s population will reach nine billion by the year 2050, with 70% crammed into urban areas. Arable land is diminishing because of poor farming practices, erosion and climate change, yet a 70% increase in food production will be required to meet demand.
Dr Dickson Despommier of Columbia University has a bold vision for the future. Vertical farms. These 30-storey glass towers would grow different kinds of produce on every level, using hydroponics. According to Despommier, 150 of these vertical farms could feed the entire population of New York City.
The supposed benefits are impressive. A drastic reduction in transport costs and greenhouse gas emissions with farms located in urban areas. Farmland could be reforested because of increased annual yields. No drought or flood losses. No pests. Heavy polluting agricultural machinery would become obsolete. Black and grey water would be filtered and recycled, sewage could be treated and used as fuel, and even the agricultural run-off that destroys marine life would be a thing of the past. It all sounds too good to be true.
Despommier knows how to work the media. He’s written a book, The Vertical Farm: Feeding the World in the 21st Century, and co-hosts the enticingly-titled podcasts This Week in Virology and This Week in Parasitism. Features have run in Time Magazine, The New York Times, the BBC and CNN. He’s even appeared on The Colbert Report, where Stephen Colbert called his 30-storey vertical farms, “pleasantly phallic”.
The hype surrounding these grand, futuristic designs has seen governments and developers from Abu Dhabi, India, China, France and the US express interest. The Illinois Institute of Technology is in the process of crafting a detailed plan for Chicago.
Despite the buzz, there are naysayers. Eminent author and environmental activist, George Monbiot, calls it “the craziest of my allies’ many miracle solutions”. He explains that aside from the litany of untested claims, there is one primary problem—light. Plants need it to grow. Unless they get it from the sun, the enormous amount of energy needed makes the process untenable. Thanet Earth, a horizontal 90-hectare glasshouse complex in the UK, requires its own mini-power stations just to provide light during winter. If single level greenhouses need extra lighting, how can plants in a 30-storey greenhouse get enough sunlight?
It’s easier to sell an idea that has never been tested than one that has failed to live up to expectations. This is the current status of large-scale vertical farming. There is no evidence to show that the plans are economically viable, let alone sustainable.
Out of the spotlight though, there are practical people making a real difference in urban centres. In Milwaukee, Will Allen and his Growing Power farm have 25 thousand pots hung in five tiers producing a thousand trays of sprouts a week. Natural Green Farms in Racine, Wisconsin produce seven thousand lettuces a month using aquaponics in an old plough factory. Meanwhile, in Singapore, a six-metre rotating vertical farm produces five times the output of a normal farm.
These initiatives and scores like them around the world show that there are highly effective urban gardening possibilities out there. However, the dream that towering glass monoliths crammed with organic vegetables will feed our growing cities remains a long way off.