Cities are for people: The limits of localism

Mass transit and energy-efficient buildings are needed more than exotic schemes for green cities.

I reworked my vertical farm piece for Worldchanging, and by the time I was done, it was an entirely different article. So if you can stand one last entry about vertical farms, this one offers a somewhat more thoughtful look at some of the principles behind sustainable development.

Columbia 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 outlandish artists’ conceptions of what such farms might look like. Colbert did his shtick. 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 that 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.

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.

Perhaps those costs pencil out (although they almost certainly do not), but the plausibility of the idea itself is in some ways beside the point. Whatever the merits of vertical farms, the enthusiasm with which this idea has been received suggests that we’re becoming mightily reductive in the way that we think about sustainability. Local is good, the thinking goes, and more local is better.

Cities offer a lot of environmental benefits, at least compared to the alternatives. There are many reasons this is so, but they all spring from a fairly basic fact: cities are built for people. Lots of people, densely packed, sharing resources. Innovations that encourage or take advantage of that density are likely to make cities more sustainable. And innovations that undermine density have a lot of work to do to overcome their inherent environmental disadvantages.

New York City, for example, recently released an ambitious plan to slash municipal carbon emissions by almost two million metric tons per year. Fully 16% of total life cycle reductions will come from a new rail and barge network built for the express purpose of hauling garbage. No one will appear on The Colbert Report to plug the new garbage barges, but the system will eliminate five million vehicle miles per year. Less congestion, less noise, less air pollution, and less greenhouse gas emissions. New York’s size and density make this project possible.

Urban vertical farms, on the other hand, fail miserably on this score. Land is one of the primary inputs for agriculture, which is why we don’t expect to see corn growing in lower Manhattan. Such spaces are better reserved for people, mass transit, mass entertainment, and businesses that depend primarily on human capital.

Our collective confusion on this point seems to be most acute when the topic is food. We intuitively understand that it doesn’t really make sense to manufacture, say, iPods in small factories scattered across hundreds of urban centers, even though iPods are consumed in just about every city in the world. We readily grasp that the economics wouldn’t work out, and we probably even understand that such a scheme wouldn’t help the environment. Efficiency benefits more than just the bottom line.

Efficiency is particularly important when it comes to housing humans. Farming surely does stress the land, but so does suburban sprawl. Suburbs mean more lawns and more roads, for starters. Environmentally speaking, it makes more sense to move another person into a city than it does to make way for a berry patch.

iPods and food differ in important ways. But they don’t differ as completely as some advocates seem to hope, and it really can make sense to house people in one place and grow food in another. Our food production system is, at present, undeniably in need of repair, but that doesn’t mean that tomatoes in skyscrapers are the logical end point to which we should strive. (Note also that urban farms, community gardens, green roofs, etc. may have a lot of things going for them, but they don’t exist on a continuum with industrial agriculture in the same way that vertical farms aspire to.)

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.

Image by University of Illinois at Urbana-Champaign.