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32 SCIENTIFIC AMERICA N November 2009
Together the world’s 6.8 billion people use
land equal in size to South America to
grow food and raise livestock—an as-
tounding agricultural footprint. And demogra-
phers predict the planet will host 9.5 billion peo-
ple by 2050. Because each of us requires a mini-
mum of 1,500 calories a day, civilization will
have to cultivate another Brazil’s worth of land—
one billion hectares—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 contamina-
tion with fertilizers, pesticides, herbicides and
silt. If current trends continue, safe drinking wa-
ter will be impossible to come by in certain
densely populated regions. Farming consumes
huge quantities of fossil fuels, too—20 percent
of all the gasoline and diesel fuel used in the U.S.
The resulting greenhouse gases are of course a
major concern, but so is the price of food as it be-
comes linked to the price of fuel, a mechanism
that 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 high-
ly mechanized farming consortia that grow crops
having higher yields—a result of genetic modi-
cation 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 administra-
tion took ofce, Secretary of Energy Steven Chu
warned that climate change could wipe out farm-
ing in California by the end of the century.
What is more, if we continue wholesale de-
forestation just to generate new farmland, glob-
al warming will accelerate at an even more cat-
astrophic rate. And far greater volumes of agri-
cultural runoff could well create enough aquatic
“dead zones” that 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 signicant
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 inict
2.5 billion people.
Clearly, radical change is needed. One stra-
KEY CONCEPTS
Farming is ruining the ■
environment, and not
enough arable land re-
mains to feed a projected
9.5 billion people by 2050.
Growing food in glass
■
high-rises could drastical-
ly reduce fossil-fuel emis-
sions and recycle city
wastewater that now pol-
lutes waterways.
A one-square-block farm
■
30 stories high could yield
as much food as 2,40 0
outdoor acres, with less
subsequent spoilage.
Existing hydroponic
■
greenhouses provide a
basis for prototype verti-
cal farms now being con-
sidered by urban planners
in cities worldwide.
—The Editors
TOPICTKTKTK
Growing crops in city skyscrapers would use less water and fossil fuel than
outdoor farming, eliminate agricultural runoff and provide fresh food
VERTICAL FARMS
RISEofThe
By Dickson Despommier
www.ScientificAmerican.com SCIENTIFIC AMERICA N 33
VERTICAL FARMS
34 SCIENTIFIC AMERICA N November 2009
us out. Farming machines of all kinds, improved
fertilizers and pesticides, plants articially bred
for greater productivity and disease resistance,
plus vaccines and drugs for common animal dis-
eases all resulted in more food than the rising
population needed to stay alive.
That is until the 1980s, when it became ob-
vious that in many places farming was stressing
the land well beyond its capacity to support vi-
able crops. Agrochemicals had destroyed the
natural cycles of nutrient renewal that intact
ecosystems use to sustain themselves. We must
switch to ag ricultural technologies that are
more ecologically sustainable.
As the noted ecologist Howard Odum sagely
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 ofcials at the United Nations
Food and Agriculture Organization to sustain-
able environmentalist and 2004 Nobel Peace
Prize winner Wangari Maathai—agree that al-
lowing farmland to revert to its natural grassy
or wooded states is the easiest and most direct
way to slow climate change—through the natu-
ral absorption of carbon dioxide, the most
abundant greenhouse gas, from the 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 10-mile-
wide strip of severely scarred land but today is
lush and vibrant, fully recovered. The once bare
corridor separating former East and West Ger-
many 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 crowd-
ed 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 tech-
niques—drip irrigation, aeroponics and hydro-
ponics—have been used successfully around the
world. In drip irrigation, plants root in troughs
of lightweight, inert material, such as vermicu-
lite, that can be used for years, and small tubes
tegic shift would do away with almost every ill
just noted: grow crops indoors, under rigorous-
ly controlled condit ions, i n 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 signicantly less water, producing
little waste, with less risk of infectious diseases,
and no need for fossil-fueled machiner y or
transport from distant rural farms. Vertical
farming could revolutionize how we feed our-
selves and the rising population to come. Our
meals would taste better, too; “locally grown”
would become the norm. The working descrip-
tion I am about to explain might sound outra-
geous at rst, but engineers, urban planners and
agronomists who have scrutinized the necessary
technologies are convinced that vertical farm-
ing is not only feasible but should be tried.
Do No Ha rm
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 min-
imum 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
[PROBLEM]
Feeding the World: Another Brazil
Growing food and raising livestock for 6.8 billion people require land equal in size to
South America. By 2050 another Brazil’s worth of area will be needed, using traditional
farming; that much arable land does not exist.
+
=
=
2050
Present
6.8 billion people
additional cropland
the size of Brazil
crop land
the size of
South America
9.5 billion people
www.ScientificAmerican.com S CIENTIFIC AMERICA N 35
ature proles. 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, cu-
cumbers and peppers 12 months a year [see il-
lustration on page 00].
Most of these operations sit in semirural ar-
eas, however, where reasonably priced land can
be found. Transporting the food for many miles
adds cost, consumes fossil fuels, emits carbon di-
oxide and causes signicant spoilage. Moving
greenhouse farming into taller structures within
city limits can solve these remaining problems. I
envision buildings perhaps 30 stories high cov-
ering an entire city block. At this scale, vertical
farms offer the promise of a truly sustainable ur-
ban life: municipal wastewater would be recy-
cled to provide irrigation water, and the remain-
ing 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 edi-
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 sci-
entists, 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 soil-
less troughs, and water with dissolved nutrients
is circulated over them. During World War II,
more than 8,000 tons of fresh vegetables were
produced hydroponically on South Pacic is-
lands for Allied forces there. Today hydroponic
greenhouses provide proof of principles for in-
door farming: crops can be produced year-
round, droughts and oods that often ruin en-
tire harvests are avoided, yields are maximized
because of ideal growing and ripening condi-
tions, 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 temper-
EUROFRESH FARMS, enclosing 318
acres outside Snowake, Ariz.,
has grown tomatoes, cucumbers
and peppers hydroponically for
more than a decade—proving
that the technology—and indoor
farming—can be efcient on a
massive scale.
36 SCIENTIFIC AMERICAN November 2009
ture will be able to rebound from our insults;
traditional farmers would be encouraged to
grow grasses and trees, getting paid to seques-
ter 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 case, people
raise two main practical questions. First, skep-
tics wonder how the concept can be economical-
ly viable, given the often in ated value of prop-
erties in cities such as Chicago, London and Par-
is. 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, Floyd Ben-
nett Air Force Base in Brooklyn lies fallow.
Abandoned in 1967, the 2.5 square miles scream
out for use. Another large tract is Governor’s Is-
land, 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
on the far west side. In addition, there are the
usual empty lots and condemned buildings scat-
tered throughout the cityscape. Several years
ago I had my graduate students survey New
York City’s ve boroughs; they found no fewer
than 120 abandoned sites waiting for change,
ble plants can be grown indoors [see illustration
on page 00]. An adjacent aquaculture center
could also raise sh, shrimp and mollusks.
Generous start-up grants and government-
sponsored research centers would be one way to
jump-start vertical farming. University partner-
ships with companies such as Cargill, Monsan-
to, Archer-Daniel Midland and IBM could also
ll the bill. Either approach would exploit the
enormous talent pool within many agriculture,
engineering and architecture schools and lead
to prototype farms perhaps ve stories tall and
one acre in footprint. These facilities could then
be the “playground” for graduate students, re-
search scientists and engineers to carry out the
necessary trial-and-error tests before a fully
functional vertical farm emerged. More mod-
est, rooftop operations on apartment complex-
es, hospitals and schools could serve as test beds
as well. Research installations already exist at
many universities, including the University of
California, Davis, Pennsylvania State Universi-
ty, Rutgers University, Michigan State Univer-
sity, and schools in Europe and Asia. One of the
best known is the University of Arizona’s Con-
trolled Environment Agriculture Center, run by
Gene Giacomelli.
Integrating food production into the tapestry
of urban life is a giant step toward making ur-
ban life sustainable. New industries will grow,
as will urban jobs never before imagined—nurs-
ery attendants, growers and harvesters. And na-
GROWING
TECHNIQUES
Three technologies would be
exploited inside vertical
farms.
DRIP IRRIGATION
Plants grow in troughs of
lightweight, inert material, such
as vermiculite, reused for years.
Small tubing on the sur face
drips nutrient-laden water
precisely at each stem’s base.
Good for grains (wheat, corn).
HYDROPONICS
Plants are held in place so their
roots lie in open troughs; water
with dissolved nutrients is
continually circulated over them.
Good for many vegetables
(tomatoes, spinach) and berries.
AEROPONICS
Plants are held in place so their
roots dangle in air that is
infused with water vapor and
nutrients. Good for root crops
(potatoes, carrots).
Floor plan Tk tk tk
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corem iure vero odiat wismodo et luptati onulla aliqui esto ex eros duisl
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ut veniam nullaorper adiamet veliquis erit lan vel elesequat iustio do
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Seedlings
planted
Conveyor belt Drip irrigation hoses
Harvester
machine
Organic
refuse drop
Elevator
Control room
Lights
(wavelength varies)
This diagram will be further simpli ed . There will only be one conveyor belt. The
front side will be tilted up, so that it will be more of a side-view of the oor plan
rather than a top-down view. This will make it easier to see the overhanging lights
with the varying wavelengths and the moving conveyor belt.
www.ScientificAmerican.com SCIENTIFIC AMERICA N 37
How it Works
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Clean water tanks
Water purication tanks
Shipping and receiving
Incinerators
Restaurant
Grocery
Visitor center
Nursery
Thin lm photovoltaic
strips along vertical
fram members
Quality
control lab
Incoming city
graywater
Organic refuse drop
Aeroponics
Hydroponics
Drip irrigation
38 SCIENTIFIC AMERICA N November 2009
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 oods 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 infesta-
tion du ri ng storage a nd transport, most of
which would be eliminated in city farms be-
cause 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 Califor-
nia and some parts of East Africa would take
advantage of abundant geothermal energy. Sun-
lled desert environments (the American South-
west, the Middle East, many parts of Central
Asia) would actually use two- or three-story
and many would bring a vertical farm to the
people who need it most, namely, the under-
served 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 ver-
tical farm concept actually helps to prove its vi-
ability. A typical Manhattan block covers about
ve acres. Critics say a 30-story building would
therefore provide only 150 acres, not much com-
pared with large outdoor farms. Yet growing oc-
curs 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 har-
vested 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
per acre, and multiple layers of dwarf crops could
be grown per oor. “Stacker” plant holders are
already used for certain hydroponic crops.
Combining these factors in a rough calcula-
tion, let us say that each oor of a vertical farm
offers four growing seasons, double the plant
density, and two layers per oor—a multiplying
factor of 16 (4 2 2). A 30-story building
covering one city block could therefore produce
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nibh eliscipsum dolorem at. Gait lamcore exercin
utpatie essit utat iSed molutpatin ut amcon ullaor
sum quatum quatie dolore min er susci et, ver ipi.
[THE AUTHOR]
Dickson Despommier is profes-
sor of public health and microbiol-
ogy at Columbia Unive rsity and
president of Vertical Farm Technol-
ogies, which functions as a clear-
ingh ouse for deve lopment work
(see www.verticalfarm.com). As a
postdoctoral fellow at the Rocke-
feller University years ago, he
became friends with René Dubos, a
renowned agric ultural sciences
researcher who introduced him to
the concept of human ecology.
www.ScientificAmerican.com SCIENTIFIC AMERICA N 39
become advocates and have indicated a strong
desire to actually build a prototype high-rise
farm. I have been approached by planners in
New York City, Portland, Ore., Los Angeles,
Las Vegas, Seattle, Surrey, British Columbia,
Toronto, Paris, Bangalore, Dubai, Abu Dhabi,
Incheon, Shanghai and Beijing. The Illinois
Inst it ute of Technology is now craf ting a
detailed 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 in-
vestment, energy and water use, and potential
crop yields. They worry about structural gird-
ers corroding over time from humidity, power
to pump water and air everywhere, and econo-
mies of scale. Detailed answers will require a
huge input from engineers, architects, indoor
agronomists and businesspeople. Perhaps bud-
ding engineers and economists would like to get
these estimations started.
Because of the Web site, the vertical farm ini-
tiative is now in the hands of the public. Its suc-
cess or failure is a function only of those who
build the prototype farms and how much time
and effort they apply. The infamous Biosphere
II closed-ecosystem project outside Tucson,
Ariz., rst 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 mas-
sive foundation would absorb. (The University
of Arizona recently acquired the rights to reex-
amine the structure’s potential.)
If vertical farming is to succeed, planners
must avoid the mistakes of this and other non-
scientic misadventures. The news is promising.
According to leading experts in ecoengineering
such as Peter Head, CEO of sustainability for
Arup, an international design and engineering
rm, no new technologies are needed to build a
large, efcient, urban vertical farm. Many en-
thusiasts have asked: “What are we waiting
for?” I have no good answer for them. ■
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 cleaned “gray water” into the
Hudson River. Instead that water could irrigate
vertical farms. Meanwhile the solid by-prod-
ucts, rich in energy, could be incinerated as well.
One typical half-pound bowel movement con-
tains 300 kilocalories of energy when inciner-
ated in a bomb calorimeter. Extrapolating to
New York’s eight million people, it is theoreti-
cally possible to derive as much as 100 million
kilowatt-hours of electricity a year, enough to
run four, 30 -story farms from bodily wastes
alone. If this material can be converted into use-
ful water and energy, city living can become
much more efcient.
Upfront investment costs will be high, as ex-
perimenters learn how to best integrate the var-
ious systems needed. That expense is why small-
er prototypes must be built rst, as they are for
any new application of technologies. Onsite re-
newable 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 difcult to predict how protable a ver-
tical 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 ve years since I rst posted some
rough thoughts and sketches about ver tical
farms on a Web site I cobbled together (www.
verticalfarm.com). Since then, architects, engi-
neers, designers and mainstream organizations
have increasingly taken note. Today many devel-
opers, investors, mayors and city planners have
MORE TO ➥
EXPLORE
Our Ecological Footprint: Reduc-
ing Human Impact on the Earth.
William E. Rees, Mathis Wackernagel
and Phil Testemale. New Society Pub-
lishers, 1998.
Cradle to Cradle: Remaking the
Way We Make Things. William Mc-
Donough and Michael Braungart.
North Point Press, 2002.
Growing Vertical. Mark Fischetti in
5EKGPVKƂE#OGTKECP'CTVJVol. 18,
No. 4, pages 74 –79; 2008.
University of Arizona Controlled Envi-
ronment Agricultural Center: http://
ag.arizona.edu/ceac
HURDLES
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