Here's the text of a presentation I did on March 4, 2015 at Northeast Sustainable Energy Association's Building Energy conference. This was the first time they addressed urban agriculture.
Everybody eats and, by last count, 35% of all households in America, or 42 million households, are growing food at home or in a community garden, up 17% in the last five years. Gardening for food tends to go up in times of economic distress. Add those households which grow flowers or have a houseplant and I'd estimate about half of us garden.
Everybody eats, half of us garden, and everybody poops. In a fully functioning ecosystem "waste equals food." Cities, neighborhoods, and buildings are all beginning to be seen and designed as metabolisms, taking in raw materials, processing them, and producing wastes which can then be used as a feedstock for other processes. We are becoming biomimetic and learning from such fellow creatures as termites how to control heat and cold and humidity. Termites also "garden" and keep livestock, one of the ways that the temperature and humidity remains constant within their mounds. We are also learning how we can design ecological systems to process our own wastes safely into fertilizer and food.
Urban agriculture is not new. Cities were built only after agriculture produced enough surplus. The Hanging Gardens of Babylon were one of the wonders of the ancient world but many forms of ancient architecture included gardens and courtyards in the designs of buildings. The market gardens around Paris were famous for the vegetables and fruits they produced in 19th century France and the greenhouse cultures of England and the Netherlands were just as well established. One of the first roof gardens in NYC was on the Ansonia Hotel in Manhattan from 1904 to 1906. They even kept cows to provide fresh milk for their guests. It is really only since the end of WWII that we've seen the rise of the supermarket and long-distance processed food culture we now have.
Energy considerations were one of the main drivers of the local food movement. Here in MA, after the first oil shock of the early 1970s, Governor Frank Sargent established a commission to examine the Commonwealth's food security. He wanted to know how much food was grown in MA and whether we could withstand another oil shock and still eat regularly. From that report, new policies to promote and support local agriculture began. At that time, there were perhaps as many as 18 farmers markets in the state. At last count, there are now 249 with 40 winter markets as well and Boston will soon have its own permanent farmers' market building. This is a return to the original method of agricultural marketing and distribution, updated to the 21st century.
Boston, like Chicago and San Francisco and other cities, now has urban agricultural zoning regulations. There are meetups and gatherings of food entrepreneurs regularly. Rooftops and empty lots are being transformed into gardens and farms. Chickens and bees are populating backyards, rooftops, and terraces. The tingle of what I call money static is all over the rapidly growing agriculture sector.
Rooftop farms are being developed all around the world. Turn key shipping container farms are also being bought and sold. Supermarkets in Basel, Switzerland and Texas and other places are producing some of the food they sell on their roofs or their walls or in adjacent greenhouses. Some of them go farther than old greenhouses by becoming controlled environment agriculture, controlling not only the temperature and light but also the composition of the air inside. People are proposing and building "plantscrapers" and vertical agriculture buildings. Old factories are becoming "pink houses," so called because they use only the red and blue wavelengths of light that leaves absorb. LED lights are tuned to those particular wavelengths to grow greens and fruits in Chicago or genetically modified nicotiana (tobacco) for medicines in the Southwest. There are also a number of countertop and windowsill automated growing systems for the home complete with Internet connections so that you can monitor your plants from the other side of the world on your smartphone. Some of them include fish, aquaponics. There are lower tech ways of doing the same thing too. Green walls are going up in restaurants, office buildings, and apartments to clean the air and provide a little additional nourishment. Urban waterways can also become food producers and there are a few groups here in Boston which are endeavoring to return shellfish to our newly cleaned harbor. Other opportunities include sprouts, mushrooms and other fungi, carbon farming and other geotherapeutic measures to deal with climate change, and even vat-grown meat. Our limit is only our imagination, the ultimate solar power.
Can urban agriculture become a significant contributor to our diet? It took only about two or three growing seasons before the WWII Victory Gardens were providing, by some estimates, up to 50% of the Homefront's vegetables. The Fenway Victory Gardens here in Boston are one of the few remaining installations from that time and are still providing food, flowers, recreation, and enjoyment for all who pass by. Here's another historical example: "Shortly before the Soviet Union's collapse, it became known informally that the ten percent of farmland allocated to kitchen gardens (in meager tenth of a hectare plots) accounted for some 90 percent of domestic food production."
Perhaps the best current example is Cuba where "there are 383,000 urban farms, covering 50,000 hectares of otherwise unused land and producing more than 1.5 million tons of vegetables with top urban farms reaching a yield of 20 kg/m2 per year of edible plant material using no synthetic chemicals—equivalent to a hundred tons per hectare. Urban farms supply 70 percent or more of all the fresh vegetables consumed in cities such as Havana and Villa Clara."
Finally, in Japan, farmers are experimenting with Solar Sharing, utilizing the “light saturation point” of photosynthesis to combine farming crops with producing photovoltaic electricity. Plants require only about 68% of the light that falls upon them for crop growth. That unused 32% can be utilized for electricity production with food and solar electricity being produced on the same property at the same time. A city building with a rooftop farm could conceivably power and feed the people who live and work in it, something that becomes increasingly possible as net zero energy building standards come on line.