The Rise of Vertical Farms, by Dickson
Despommier, in Scientific American, 2009 Nov.
Together the world's 6.8 billion people use land equal in
size to South America to grow food and raise livestock--an
astounding agricultural footprint. And demographers predict
the planet will host 9.5 billion people by 2050. Because each
of us requires a minimum of 1,500 calories a day, civilization
will have to cultivate another Brazil's worth of land--2.1
billion acres--if farming continues to be practiced as it
is today. That much new, arable earth simply does not exist.
To quote the great American humorist Mark Twain: "Buy
land. They're not making it any more."
Agriculture also uses 70 percent
of the world's available freshwater for irrigation, rendering
it unusable for drinking as a result of contamination with
fertilizers, pesticides, herbicides and silt. If current trends
continue, safe drinking water will be impossible to come by
in certain densely populated regions. Farming involves huge
quantities of fossil fuels, too--20 percent of all the gasoline
and diesel fuel consumed in the U.S. The resulting greenhouse
gas emissions are of course a major concern, but so is the
price of food as it becomes linked to the price of fuel, a
mechanism that roughly doubled the cost of eating in most
places worldwide between 2005 and 2008.
Some agronomists believe that the
solution lies in even more intensive industrial farming, carried
out by an ever decreasing number of highly mechanized farming
consortia that grow crops having higher yields--a result of
genetic modification and more powerful agrochemicals. Even
if this solution were to be implemented, it is a short-term
remedy at best, because the rapid shift in climate continues
to rearrange the agricultural landscape, foiling even the
most sophisticated strategies. Shortly after the Obama administration
took office, Secretary of Energy Steven Chu warned the public
that climate change could wipe out farming in California by
the end of the century.
What is more, if we continue wholesale
deforestation just to generate new farmland, global warming
will accelerate at an even more catastrophic rate. And far
greater volumes of agricultural runoff could well create enough
aquatic "dead zones" to turn most estuaries and
even parts of the oceans into barren wastelands.
As if all that were not enough to
worry about, foodborne illnesses account for a significant
number of deaths worldwide--salmonella, cholera, Escherichia
coli and shigella, to name just a few. Even more of a problem
are life-threatening parasitic infections, such as malaria
and schistosomiasis. Furthermore, the common practice of using
human feces as a fertilizer in most of Southeast Asia, many
parts of Africa, and Central and South America (commercial
fertilizers are too expensive) facilitates the spread of parasitic
worm infections that afflict 2.5 billion people.
Clearly, radical change is needed.
One strategic shift would do away with almost every ill just
noted: grow crops indoors, under rigorously controlled conditions,
in vertical farms. Plants grown in high-rise buildings erected
on now vacant city lots and in large, multistory rooftop greenhouses
could produce food year-round using significantly less water,
producing little waste, with less risk of infectious diseases,
and no need for fossil-fueled machinery or transport from
distant rural farms. Vertical farming could revolutionize
how we feed ourselves and the rising population to come. Our
meals would taste better, too; "locally grown" would
become the norm.
The working description I am about
to explain might sound outrageous at first. But engineers,
urban planners and agronomists who have scrutinized the necessary
technologies are convinced that vertical farming is not only
feasible but should be tried.
Do No Harm
Growing our food on land that used
to be intact forests and prairies is killing the planet, setting
up the processes of our own extinction. The minimum requirement
should be a variation of the physician's credo: "Do no
harm." In this case, do no further harm to the earth.
Humans have risen to conquer impossible odds before. From
Charles Darwin's time in the mid-1800s and forward, with each
Malthusian prediction of the end of the world because of a
growing population came a series of technological breakthroughs
that bailed us out. Farming machines of all kinds, improved
fertilizers and pesticides, plants artificially bred for greater
productivity and disease resistance, plus vaccines and drugs
for common animal diseases all resulted in more food than
the rising population needed to stay alive.
That is until the 1980s, when it
became obvious that in many places farming was stressing the
land well beyond its capacity to support viable crops. Agrochemicals
had destroyed the natural cycles of nutrient renewal that
intact ecosystems use to maintain themselves. We must switch
to agricultural technologies that are more ecologically sustainable.
As the noted ecologist Howard Odum
reportedly observed: "Nature has all the answers, so
what is your question?" Mine is: How can we all live
well and at the same time allow for ecological repair of the
world's ecosystems? Many climate experts--from officials at
the United Nations Food and Agriculture Organization to sustainable
environmentalist and 2004 Nobel Peace Prize winner Wangari
Maathai--agree that allowing farmland to revert to its natural
grassy or wooded states is the easiest and most direct way
to slow climate change. These landscapes naturally absorb
carbon dioxide, the most abundant greenhouse gas, from the
ambient air. Leave the land alone and allow it to heal our
planet.
Examples abound. The demilitarized
zone between South and North Korea, created in 1953 after
the Korean War, began as a 2.5-mile wide strip of severely
scarred land but today is lush and vibrant, fully recovered.
The once bare corridor separating former East and West Germany
is now verdant. The American dust bowl of the 1930s, left
barren by overfarming and drought, is once again a highly
productive part of the nation's breadbasket. And all of New
England, which was clear-cut at least three times since the
1700s, is home to large tracts of healthy hardwood and boreal
forests.
The Vision
For many reasons, then, an increasingly
crowded civilization needs an alternative farming method.
But are enclosed city skyscrapers a practical option?
Yes, in part because growing food
indoors is already becoming commonplace. Three techniques
--drip irrigation, aeroponics and hydroponics --have been
used successfully around the world. In drip irrigation, plants
root in troughs of lightweight, inert material, such as vermiculite,
that can be used for years, and small tubes running from plant
to plant drip nutrient-laden water precisely at each stem's
base, eliminating the vast amount of water wasted in traditional
irrigation. In aeroponics, developed in 1982 by K. T. Hubick,
then later improved by NASA scientists, plants dangle in air
that is infused with water vapor and nutrients, eliminating
the need for soil, too.
Agronomist William F. Gericke is
credited with developing modern hydroponics in 1929. Plants
are held in place so their roots lie in soilless troughs,
and water with dissolved nutrients is circulated over them.
During World War II, more than eight million pounds of vegetables
were produced hydroponically on South Pacific islands for
Allied forces there. Today hydroponic greenhouses provide
proof of principles for indoor farming: crops can be produced
yearround, droughts and floods that often ruin entire harvests
are avoided, yields are maximized because of ideal growing
and ripening conditions, and human pathogens are minimized.
Most important, hydroponics allows
the grower to select where to locate the business, without
concern for outdoor environmental conditions such as soil,
precipitation or temperature profiles. Indoor farming can
take place anywhere that adequate water and energy can be
supplied. Sizable hydroponic facilities can be found in the
U.K., the Netherlands, Denmark, Germany, New Zealand and other
countries. One leading example is the 318-acre Eurofresh Farms
in the Arizona desert, which produces large quantities of
high-quality tomatoes, cucumbers and peppers 12 months a year.
Most of these operations sit in semirural
areas, however, where reasonably priced land can be found.
Transporting the food for many miles adds cost, consumes fossil
fuels, emits carbon dioxide and causes significant spoilage.
Moving greenhouse farming into taller structures within city
limits can solve these remaining problems. I envision buildings
perhaps 30 stories high covering an entire city block. At
this scale, vertical farms offer the promise of a truly sustainable
urban life: municipal wastewater would be recycled to provide
irrigation water, and the remaining solid waste, along with
inedible plant matter, would be incinerated to create steam
that turns turbines that generate electricity for the farm.
With current technology, a wide variety of edible plants can
be grown indoors [see illustration on opposite page]. An adjacent
aquaculture center could also raise fish, shrimp and mollusks.
Start-up grants and government-sponsored research centers
would be one way to jumpstart vertical farming. University
partnerships with companies such as Cargill, Monsanto, Archer
Daniels Midland and IBM could also fill the bill. Either approach
would exploit the enormous talent pool within many agriculture,
engineering and architecture schools and lead to prototype
farms perhaps five stories tall and one acre in footprint.
These facilities could be the "playground" for graduate
students, research scientists and engineers to carry out the
necessary trial-and-error tests before a fully functional
farm emerged. More modest, rooftop operations on apartment
complexes, hospitals and schools could be test beds, too.
Research installations already exist at many schools, including
the University of California, Davis, Pennsylvania State University,
Rutgers University, Michigan State University, and schools
in Europe and Asia. One of the best known is the University
of Arizona's Controlled Environment Agriculture Center, run
by Gene Giacomelli.
Integrating food production into
city living is a giant step toward making urban life sustainable.
New industries will grow, as will urban jobs never before
imagined--nursery attendants, growers and harvesters. And
nature will be able to rebound from our insults; traditional
farmers would be encouraged to grow grasses and trees, getting
paid to sequester carbon.
Eventually selective logging would
be the norm for an enormous lumber industry, at least throughout
the eastern half of the U.S.
Practical Concerns
In recent years I have been speaking
regularly about vertical farms, and in most cases, people
raise two main practical questions. First, skeptics wonder
how the concept can be economically viable, given the often
inflated value of properties in cities such as Chicago, London
and Paris. Downtown commercial zones might not be affordable,
yet every large city has plenty of less desirable sites that
often go begging for projects that would bring in much needed
revenue.
In New York City, for example, the
former Floyd Bennett Field naval base lies fallow. Abandoned
in 1972, the 2.1 square miles scream out for use. Another
large tract is Governors Island, a 172-acre parcel in New
York Harbor that the U.S. government recently returned to
the city. An underutilized location smack in the heart of
Manhattan is the 33rd Street rail yard. In addition, there
are the usual empty lots and condemned buildings scattered
throughout the city. Several years ago my graduate students
surveyed New York City's five boroughs; they found no fewer
than 120 abandoned sites waiting for change, and many would
bring a vertical farm to the people who need it most, namely,
the underserved inhabitants of the inner city. Countless similar
sites exist in cities around the world. And again, rooftops
are everywhere.
Simple math sometimes used against
the vertical farm concept actually helps to prove its viability.
A typical Manhattan block covers about five acres. Critics
say a 30-story building would therefore provide only 150 acres,
not much compared with large outdoor farms. Yet growing occurs
year-round. Lettuce, for example, can be harvested every six
weeks, and even a crop as slow to grow as corn or wheat (three
to four months from planting to picking) could be harvested
three to four times annually. In addition, dwarf corn plants,
developed for NASA, take up far less room than ordinary corn
and grow to a height of just two or three feet. Dwarf wheat
is also small in stature but high in nutritional value. So
plants could be packed tighter, doubling yield greenhouse);
courtesy of eurofresh farms (aerial view) per acre, and multiple
layers of dwarf crops could be grown per floor. "Stacker"
plant holders are already used for certain hydroponic crops.
Combining these factors in a rough
calculation, let us say that each floor of a vertical farm
offers four growing seasons, double the plant density, and
two layers per floor--a multiplying factor of 16 (4 ×
2 × 2). A 30-story building covering one city block
could therefore produce 2,400 acres of food (30 stories ×
5 acres × 16) a year. Similarly, a one-acre roof atop
a hospital or school, planted at only one story, could yield
16 acres of victuals for the commissary inside. Of course,
growing could be further accelerated with 24-hour lighting,
but do not count on that for now.
Other factors amplify this number.
Every year droughts and floods ruin entire counties of crops,
particularly in the American Midwest. Furthermore, studies
show that 30 percent of what is harvested is lost to spoilage
and infestation during storage and transport, most of which
would be eliminated in city farms because food would be sold
virtually in real time and on location as a consequence of
plentiful demand. And do not forget that we will have largely
eliminated the mega insults of outdoor farming: fertilizer
runoff, fossil-fuel emissions, and loss of trees and grasslands.
The second question I often receive
involves the economics of supplying energy and water to a
large vertical farm. In this regard, location is everything
(surprise, surprise). Vertical farms in Iceland, Italy, New
Zealand, southern California and some parts of East Africa
would take advantage of abundant geothermal energy. Sun-filled
desert environments (the American Southwest, the Middle East,
many parts of Central Asia) would actually use two- or three-story
structures perhaps 50 to 100 yards wide but miles long, to
maximize natural sunlight for growing and photovoltaics for
power. Regions gifted with steady winds (most coastal zones,
the Midwest) would capture that energy. In all places, the
plant waste from harvested crops would be incinerated to create
electricity or be converted to biofuel.
One resource that routinely gets
overlooked is very valuable as well; in fact, communities
spend enormous amounts of energy and money just trying to
get rid of it safely. I am referring to liquid municipal waste,
commonly known as blackwater. New York City occupants produce
one billion gallons of wastewater every day. The city spends
enormous sums to cleanse it and then dumps the resulting "gray
water" into the Hudson River. Instead that water could
irrigate vertical farms. Meanwhile the solid by-products,
rich in energy, could be incinerated as well. One typical
half-pound bowel movement contains 300 kilocalories of energy
when incinerated in a bomb calorimeter. Extrapolating to New
York's eight million people, it is theoretically possible
to derive as much as 100 million kilowatt-hours of electricity
a year from bodily wastes alone, enough to run four, 30-story
farms. If this material can be converted into useful water
and energy, city living can become much more efficient.
Upfront investment costs will be
high, as experimenters learn how to best integrate the various
systems needed. That expense is why smaller prototypes must
be built first, as they are for any new application of technologies.
Onsite renewable energy production should not prove more costly
than the use of expensive fossil fuel for big rigs that plow,
plant and harvest crops (and emit volumes of pollutants and
greenhouse gases). Until we gain operational experience, it
will be difficult to predict how profitable a vertical farm
could be. The other goal, of course, is for the produce to
be less expensive than current supermarket prices, which should
be attainable largely because locally grown food does not
need to be shipped very far.
Desire
It has been five years since I first
posted some rough thoughts and sketches about vertical farms
on a Web site I cobbled together (www. verticalfarm.com).
Since then, architects, engineers, designers and mainstream
organizations have increasingly taken note. Today many developers,
investors, mayors and city planners have become advocates
and have indicated a strong desire to actually build a prototype
highrise farm. I have been approached by planners in New York
City, Portland, Ore., Los Angeles, Las Vegas, Seattle, Surrey,
B.C., Toronto, Paris, Bangalore, Dubai, Abu Dhabi, Incheon,
Shanghai and Beijing. The Illinois Institute of Technology
is now crafting a de tailed plan for Chicago.
All these people realize that something
must be done soon if we are to establish a reliable food supply
for the next generation. They ask tough questions regarding
cost, return on investment, energy and water use, and potential
crop yields. They worry about structural girders corroding
over time from humidity, power to pump water and air everywhere,
and economies of scale. Detailed answers will require a huge
input from engineers, architects, indoor agronomists and businesspeople.
Perhaps budding engineers and economists would like to get
these estimations started.
Because of the Web site, the vertical
farm initiative is now in the hands of the public. Its success
or failure is a function only of those who build the prototype
farms and how much time and effort they apply. The infamous
Biosphere 2 closed-ecosystem project outside Tucson, Ariz.,
first inhabited by eight people in 1991, is the best example
of an approach not to take. It was too large of a building,
with no validated pilot projects and a total unawareness about
how much oxygen the curing cement of the massive foundation
would absorb. (The University of Arizona now has the rights
to reexamine the structure's potential.)
If vertical farming is to succeed,
planners must avoid the mistakes of this and other nonscientific
misadventures. The news is promising. According to leading
experts in ecoengineering such as Peter Head, who is director
of global planning at Arup, an international design and engineering
firm based in London, no new technologies are needed to build
a large, efficient urban vertical farm. Many enthusiasts have
asked: "What are we waiting for?" I have no good
answer for them.
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