In many cities throughout the United States, sludge derived from wastewater treatment plants is processed further, then turned into high-grade topsoil and sold to farming communities. The cities of New York and Boston, for example, have operating sludge-to-fertilizer schemes. The problem is that most municipal sludge is often heavily contaminated by copper, mercury, zinc, arsenic, and chromium, which limits its use for farming.
Some vertical farms could act as stand-alone water-regenerating facilities. A cold-brine pipe system could be engineered to aid in the condensation and harvesting of moisture released by the plants. Plants in the vertical farm could convert safe-to-use grey water into drinking water by transpiration. The fact that the entire farm would be a closed-loop system would allow us to recover this unrealized, highly valued resource.
The resulting purified water would then be used in other vertical farms for raising fish and even algae, and for growing commercial crops. Ultimately, any water that emerged from the vertical farm would be drinkable, thus bringing it back into the community that brought it to the farm to begin with. New York City discards some one billion gallons of treated grey water every day into the Hudson River estuary. If industrial-quality water costs five cents a gallon (a conservative estimate), reclamation would be well worth the effort, even if the system cost as much as $30 billion to construct and manage. This is hardly a pie-in-the-sky scheme. A portion of Orange County, California, with a population of approximately 500,000, converts grey water back into tap water using a state-of-the-art purification system that cost its taxpayers $500 million to install. It was worth every penny.
The End of Pollution
The most pressing case for urban agriculture lies in our failure to handle waste, in particular agricultural runoff (leftover irrigation water laden with pesticides, herbicides, fertilizer, and silt). Agriculture is responsible for more ecosystem disruption than any other kind of pollution. What’s more, today’s farmers can’t do much about it: Floods dictate the timing and extent of runoff.
Some 70 percent of all available freshwater on earth is used for irrigation, and the resulting unused portion is returned to countless rivers and streams. Runoff that reaches the oceans disconnects other ecological systems. Nitrogen fertilizer (ammonium nitrate) has the chemical property of absorbing oxygen from water. Agricultural runoff reduces the vibrant, abundant undersea life of coral reefs to barren remnants. Deforestation for purposes of freeing up farmland reinforces this toxic cycle by adding more nitrogen fertilizer to the mix and by further reducing the earth’s capacity to sequester carbon from the atmosphere.
In a city with vertical farms, waste will be replaced with the recovery of unrealized energy. In nature, there is no waste. In the new eco-city, discarding anything without finding another use for it would be quite unthinkable. Imagine how absurd it would be to siphon off a gallon’s worth of gasoline from the family car and pour it down the sewer. Yet this is equivalent to what we are doing with everything we now throw away.
Cities of the Near Future
Today’s cities fail to meet even the minimum standards of self-reliance. No city lives within its own means. Everything consumed is produced outside the city, and as a result, waste accumulates at an alarming rate. A midsize city annually produces gigatons of solid material and billions of gallons of wastewater. Add to that the billions of dollars spent annually trying to get rid of this unwanted material, and you have a clear picture of our current environmental crisis.
But it doesn’t have to be this way. Technology continues to astound us with new proof of the inventiveness of the human species. Computers keep getting faster and more sophisticated. We are contemplating establishing colonies on the moon and on Mars. We have even collected the dust emitted from the tail of a comet. Yet despite this astounding prowess, most of the earth’s inhabitants remain oblivious to the profound, and largely negative, effect they have on the planet. We continue to urbanize without building cities that are equipped to handle their populations. Most evolutionary biologists agree that continued failure to live within our means will relegate the human species to the fossil record.
Science has led the way in helping us to understand the toll we are taking on the planet. Satellites report on the status of many of the factors that contribute to climate change. Ground-based and satellite observations of coal-burning power plants, for example, support the unavoidable conclusion that we are the root cause of it. Now that we’ve identified the problem, we can devote our energy to finding a set of solutions. Producing food crops in mass quantities within the city limits would be a step in the right direction. The good news is that many of us are already trying to repair the environment through scientific research and philanthropic support. This is good evidence of our ability to behave in a selfless and altruistic manner when we have the opportunity to do so.
It’s time to accept our connectedness to the rest of the natural world. There is only so much natural capital out there, and we are on the verge of exhausting it. Building self-sustaining cities now will allow the land to heal itself, thereby restoring balance between our lives and the rest of nature.
Chapter 1
Remodeling Nature
Nothing endures but change.
—HERACLITUS
Down on the Farm
Ten to twelve thousand years ago, all over the globe, humans began systematically to modify their environment by purposely domesticating parts of the natural world to meet their basic biological needs. Creating a reliable source of food and water was at the top of their list. Apparently, as if a switch had been thrown, we nearly unanimously tired of hunting and gathering. We learned how to grow crops derived from wild plants (corn, wheat, barley, rice) and to selectively breed various four-legged animals into tame versions of their wild counterparts for food, transportation, and, of course, labor. We catapulted out of the biosphere and into the technosphere, where we now find ourselves deeply embedded. Along the way, all natural systems suffered under our heavy foot of progress. It’s the “progress” part of our history that we are currently having a problem with; the environmental crises of today have their roots deeply embedded in that last bit of human evolution. To understand the cumulative negative effects we have had on the natural world since we began to urbanize, we must first understand the essence of what the world was like without us in it (for glimpses of its former glory, see the BBC production Planet Earth; to see what the world might become again if we were to suddenly disappear, see Alan Weisman’s book The World Without Us). By grasping the basics of what allows natural assemblages of plants and animals to organize into mutually dependent networks called ecosystems, we gain insight into how a city might be redesigned to mimic that process. It is my contention that if the built environment could behave by reflecting the integration of functions equivalent to that of an ecosystem, life would be a lot more bearable for all of us, and more economically stable, too.
Nature’s Manifesto
The biosphere matured when terrestrial plants and animals became mutually dependent upon other each other in a harmonic symbiotic relationship. This took place over billions of years of evolutionary history. One current theory as to how all this happened, proposed first by Lynn Margulis and James Lovelock, who termed it the “Gaia hypothesis,” suggests that once primitive life on earth arose, it began to modify the environment to suit its own needs. Today, most geochemists and ecologists would agree that this theory is the most reasonable explanation for how nutrients become recycled, down to how the ambient temperature of the entire planet is maintained. Symbiosis became the norm and now defines all of nature. Virtually every living thing can be shown to be dependent (either directly or indirectly) upon all other living things, except perhaps for those microbial extremophiles that live off the scant nutrients stored in solid rock. All green plants are able to grow and reproduce using only the energy contained in sunlight, together with water and a few (at least sixteen) essential minerals they obtain from the solid substrate (mostly
soil). They excrete oxygen (their gaseous waste product) into the atmosphere and store sugars and proteins in their tissues.
Herbivorous animals (humans included) take advantage of this bonanza of resources, inhaling oxygen and eating plants to fulfill nutritional requirements. Animals then routinely excrete solid and liquid wastes into the environment (future plant nutrients) and exhale carbon dioxide (our gaseous waste product) into the atmosphere, providing photosynthetic plants the opportunity to continue the cycle of life. When plants and animals die, as they all must, communities of soil-based microbes known as detritivores return the elements contained in their carcasses to the earth by the process of decay, providing a kind of natural fertilizer for the next generation of plants; it’s a natural “ashes to ashes” strategy for nutrient recycling. It has existed this way for some 400 million years and will undoubtedly go on for some time to come, with or without us. The fact that it has survived for so long in the face of extraordinary environmental changes suggests strongly that it is an incredibly resilient and highly redundant system, one that is almost impossible to destroy. This augurs well for the ability of fragmented ecosystems to repair themselves if we simply learn how to keep our hands off and mind our own business.
Strength in Numbers
When a mixed group of plant species, all with similar tolerances for temperature and humidity, grow in a given geographic region, their very presence attracts animals of different species to coinhabit that region. The result is the eventual establishment of mutually dependent relationships, in which all the life forms in that zone, including the microbes, join to share in the flow of energy provided by the sun. This is the bare-bones definition of a functional ecosystem. Ecosystems are also known as biomes. Mostly, ecosystems refer to terrestrial situations, and for our purposes, I will stick to this definition. The one characteristic they all share is that primary productivity (the total mass of plants produced over a year in a given geographically defined region) is limited by the total amount of energy received and processed. In fact, the amount of available energy actually determines the very nature of each ecosystem. For example, rain forests have an abundance of sunlight and a year-round growing season, allowing all of the inhabitants that live there to prosper. In contrast, alpine forests are limited by a short growing season and lack of warmth. No ecosystem can exceed the limits of biomass production, which is strictly regulated by the total amount of incoming energy, period. In years of high productivity, energy is used to its maximum efficiency, and in lean years, largely regulated by fluctuations in weather patterns, the result is lower bioproductivity. Nature adjusts to a varying supply of calories. Cities do not follow this simple rule of nature, and therein lies the problem.
Vive La Différence
Ecosystems vary from place to place, from the kinds of plants and animals found in each to the physical makeup of the landscapes. The most important features of an ecosystem are the annual temperature regimes and precipitation profiles, which vary greatly with latitude and altitude. Hence, there is a plethora of varied, vibrant, robust assemblages of life that have flourished for hundreds of thousands of years. Only recently in geological time have we been able to make any impact on their functionality. In just the last ten thousand years we have spread ourselves over the entire planet, encroaching into all terrestrial ecosystems and fragmenting most of them with our farms, grazing lands, and human settlements. We invented agriculture at least six different times across the entire globe. Food production freed us from wandering and allowed for the rise of what we have come to refer to as civilization. Unfortunately, along the way we forgot to pay attention to the processes that encouraged our own evolution—processes that are still at work today. Many ecologists, myself included, hold that unless we make peace with the natural world, we will surely lose our place in it.
The Enemy Within
To frame the problem in an ecological perspective, in stark contrast to the natural world around us, urban centers (the “technosphere” described by William McDonough and Michael Braungart in Cradle to Cradle) have no apparent cutoffs regarding constraints of growth. This is especially true in the poorest countries. It’s a rare situation that results in uncontrolled growth due to extreme wealth, but it happens, as well. Abu Dhabi, Dubai, and the United States routinely exceed their quotas for almost every resource, including food, water, and energy. The result of such excessive behavior has led to the problems facing us today. By defining the problem in ecological terms, we may be able to pave the way for a complete overhaul of the way we carry out our daily lives. Today, nearly 50 percent of us choose to live in cities and surrounding suburbs. These crowded urban centers rely heavily on importing food, ores, and other essential resources. If we continue to rely on harvesting resources from an environment we have created, whose production is solely dependent on using more and more fertilizers, herbicides, and pesticides, those forced ecological situations will soon fail and we will be left stranded. In fact, many agricultural regions are already failing, and others are soon to follow.
So, the real question is, can a city bio-mimic an intact ecosystem with respect to the allocation and use of essential resources and, at the same time, provide a healthy, nurturing, sustainable environment for its inhabitants? As the reader will see in what follows, I think the answer is an emphatic yes. In fact, we have no choice if we want not just to survive but to thrive. We have all the tools to do so. All we have to do is apply them creatively to address this single question. Built into this ecological survival strategy is the eventual repair of much of what we have damaged along the way to becoming seven billion strong.
Having It Both Ways
Repairing the environment and still having enough to eat may seem like mutually exclusive goals. If the world’s population continues to increase and we need to place more and more land into agriculture, and if in doing so we are forced to cut down more forest, how can we expect the environment to heal itself? In theory, the solution is straightforward: Grow most of our food crops within specially constructed buildings located inside the city limits using methods that do not require soil. This would allow for the conversion of an equivalent amount of farmland back into whatever ecosystem was there originally, usually hardwood forest. The regrowth of the forests would eventually sequester significant amounts of carbon from the atmosphere and begin the healing process. Biodiversity would be increased, and ecosystem services, such as flood control and cleaning of the air, would be strengthened. The more urban farms there are, the larger the amount of carbon that would be converted to cellulose in the form of trees. It is that simple.
Technology Rules
To most who hear about this scheme for the first time, it all sounds too simplistic to actually have any chance of working. It sounds downright naive and impractical. Yet, over the last ten years, the more I and my 106 bright and enthusiastic graduate students thought it through, the more reasonable the idea became. We called it “vertical farming.” It is a concept whose premise is easy to envision: Stack up “high-tech” greenhouses on top of each other and locate these “super” indoor farms inside the urban landscape, close to where most of us have chosen to live. However, I came to realize early on that making it happen will not be an easily attainable goal, and certainly not simple from an engineering and design perspective.
Although there are at present no examples of vertical farms, we know how to proceed—we can apply hydroponic and aeroponic farming methodologies in a multistory building and create the world’s first vertical farms. Some parts of the world are rapidly moving toward such a scheme already, especially those countries—the Netherlands, Belgium, Germany, Iceland, New Zealand, Australia, China, Dubai, Abu Dhabi, and Japan, to name but a few—that are running short of arable farmland and have the resources to contemplate replacing the accepted traditional agricultural paradigm with something new and more efficient. Other, less affluent countries, such as Niger, Chad, Mali, Ethiopia, Darfur, and North Korea, desperately need vertical farms to resc
ue enormous populations from extreme hunger.
Vertical farming practiced on a large scale in urban centers holds the promise that sustainable urban life is not only possible but highly desirable and technologically achievable. With all the advances made over the last ten years in the sustainable use of resources, a city can now choose to become a functional urban equivalent to a natural ecosystem by employing high-tech versions of waste-to-energy strategies, food production, and water-recovery systems. In that way, it can process all resources that generate waste back into usable resources without further damaging the environment.
Desirable Attributes
Ideally, vertical farms should be cheap to build, modular, durable, easily maintained, and safe to operate. They should also be independent of economic subsidies and outside support once they are up and running, which means they should also generate income for the owners. If these conditions are realized through an ongoing, comprehensive research program that leads to construction of efficient, productive vertical farms, urban agriculture could provide a continuous, abundant, and varied food supply for the 60 percent of the population that will live in cities twenty years from now. Ironically, the migration to cities is being driven by the “plight” of the farmer. People move to cities for economic reasons—when a city’s economy is good it pulls people to it. Droughts and floods that affect huge areas of agricultural land result in mass migration of farmers to cities in bad times. Urban farming opportunities that arise directly from the creation of vertical farms could provide jobs for these people. What could be a better outcome for displaced agricultural personnel than for them to discover that they can still plant and harvest, only now in a controlled environment? No more praying for rain or sunshine or moderate temperatures; they could save their prayers for things like winning the lottery.
The Vertical Farm Page 2