By the year 2050, nearly 80 percent of the Earth’s population will reside in urban centers. Applying the most conservative estimates to current demographic trends, the human population will increase by about three billion people during the interim. On an urban planet, closing resource and energy loops — creating zero-waste systems for meeting the needs of people who live in highly dense cities — floats in front of us, grail-like, as a goal. An estimated one trillion hectares of new land (about 20 percent more land than is represented by the country of Brazil) will be needed to grow enough food to feed them, if traditional farming practices continue as they are practiced today. At present, throughout the world, over 80 percent of the land that is suitable for raising crops is in use. Historically, some 15 percent of that has been laid waste by poor management practices. What can be done to avoid this impending disaster?

An entirely new approach to indoor farming must be invented, employing cutting-edge technologies. Columbia University professor Dickson Despommier has generated a fair amount of attention with his concept for “vertical farms:” stacked, self-contained urban biosystems that would — theoretically — supply fresh produce for city residents year round. The New York Times showcased artists’ conceptions of what such farms might look like. Twelve pilot projects are supposedly under consideration, in locations as far-flung as China and Dubai.

The concept has captured the imagination of at least the sliver of the public, who laments the enormous resource demands of our food production system and yearns for something easier on the land, easier on our aquifers, and less demanding of fossil fuels. Vertical farms seem to promise all that. But first and foremost, a vertical farm must be efficient, cheap to construct and safe to operate. Vertical farms, many stories high, could be situated in the heart of the world’s urban centers. If successfully implemented, they may offer the promise of urban renewal, sustainable production of a safe and varied food supply (year-round crop production) and the eventual repair of ecosystems that have been sacrificed for horizontal farming.

I still need a bunch of convincing that vertical farming can, with the designs offered and technologies currently available, make sense on a grand scale. But it’s a promising idea.

Promising, of course, is different than delivering. Construction requires a lot of energy. Keeping vegetables warm in winter requires a lot of energy. Recycling water requires a lot of energy. Generating artificial sunlight requires a lot of energy. In other words, the secret ingredient that makes vertical farms work (assuming they work at all) is boatloads of energy. No one seems to have actually done the math on the monetary and environmental costs of such a scheme, but they would no doubt be considerable.

In its most superficial aspect, the vertical farm is a hot-looking amenity for a progressive city. But its deeper potential is as a tool that might prove invaluable when times get more desperate. Climate-controlled skyscrapers aren’t as susceptible to crazy weather fluctuations as conventional farms. As the global population struggles to shrink its footprint by congregating in cities, reducing our dependence on fossil fuels and devising ways to feed more people without degrading more natural green space, a working farm in the sky wouldn’t be a bad thing to know how to build.

I do think it may be worth investing now in developing an idea that might help to save us when we need it. And I applaud thinkers like Despommier (and Seattle-based Mithun), whose creativity will bring us closer to the solutions we need. It’s also worth considering that what we are building in an urban farm is more than just a showpiece of great design. I hope that, no matter which city accepts the challenge first, executing a wildly imaginative idea like this one should be a project considered with utmost practicality. As the world’s population booms, we need to keep to continue growing and greening our cities. And that means keeping the focus where it belongs: on people. Our cities could be seen as machines for transforming water, biomass and minerals into people and pollution. If we’re serious about building a bright green future, we need to redesign those machines, keeping the people, but bringing the mechanism into a balanced cycle with the Earth. That’s going be a bit challenging.

One thing we can do to increase our odds of success is to understand how our cities grew into the complex systems they now are. Indeed, not understanding what accidents, choices and forces shaped our cities almost guarantees that the new designs, policies, plans and technologies we introduce will either fail or produce monstrous unintended consequences. As Wendell Barry once said, “All good work remembers its past.”

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  1. Good article from the Milwaukee Journal Sentinel in 2008 about a small-scale version of vertical farming.

    “Perched on the Edge of a Comeback”

    IIRC, Perch retails for around $15/pound on the web. Based on this article, can you do 4,000lbs from 10,000 perch? Let’s be conservative and say 3,000lbs. That retails for around $45,000. You have to keep the water warm and there are other costs, initial cost of the fingerlings, fish food, labor, insurance, cleaning and gutting…. but there’s some cash flow here in addition to the water cress and other plants you harvest.

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