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  • From: "Tradingpost" <tradingpost@lobo.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Farms in Skyscrapers Won't Solve Our Food Problems
  • Date: Mon, 03 May 2010 21:04:07 -0600



Why Planting Farms in Skyscrapers Won't Solve Our Food Problems
'Vertical' farming would not solve the most pressing agricultural problems --
just make things worse.
May 3, 2010 |
http://www.alternet.org/food/146686/why_planting_farms_in_skyscrapers_won%27t_solve_our_food_problems?page=entire

Agriculture in America has become an ecological, social and nutritional
disaster of sufficiently huge scale to inspire a frenzy of book-writing,
filmmaking, conference-holding and project-initiating in recent years. The
critiques that emerge are often right on the money, highlighting pesticide
and nitrate pollution, soil erosion, the consequences of meat production in
feedlots and confinement sheds, the destruction of rural communities and the
poor nutritional quality of food. But the solutions being proposed have not,
for the most part, been of the same scale as the problems; most would do
little more than nibble at the edges of America's long-running agricultural
fiasco.

A striking example of such ill fit between problem and proposed response can
be found in the November 2009 issue of Scientific American, where Dickson
Despommier, a professor of public health and environmental health sciences at
Columbia University, made his case for what he calls "vertical farms," a
vision he promotes through his site verticalfarm.com.

After doing a very good job of describing the terrible toll that agriculture
takes on soil, water, and biodiversity across the globe, Despommier's article
lays out a proposal to replace soil-based farming with a system of producing
food crops in tall urban buildings-to, he writes, "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 transĀ¬port from distant rural farms."

Despommier describes how one of his scenarios-which are based on the use of
hydroponic or "aeroponic" methods of growing plants without soil-might work:
"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." By
extrapolating numbers like those and assuming extraordinary leaps in
technology, as well as the repeal of Murphy's Law, he has made such a
convincing case for vertical farms that, he claims, "many developers,
investors, mayors and city planners have become advocates." Time magazine has
run a generally positive story on the concept. And an Australian architect is
currently planning to build the first full-scale vertical farm, in China.

The idea for vertical agriculture grows out of the realization that there are
not enough exposed horizontal surfaces available in most urban areas to
produce the quantities of food needed to feed urban populations. Although the
concept has provided opportunities for architecture students and others to
create innovative, sometimes beautiful building designs, it holds little
practical potential for providing food. Even if vertical farming were
feasible on a large scale, it would not solve the most pressing agricultural
problems; rather, it would push the dependence of food production on
industrial inputs to even greater heights. It would ensure that dependence by
depriving crops not only of soil but also of the most plentiful and
ecologically benign energy source of all: sunlight.

Groping in the dark

Agriculture as it has always been practiced-call it "horizontal
farming"-casts an extremely broad, green "net" across the landscape to
capture solar energy, which plants use in producing food. Photosynthesis
converts a small percentage of the solar energy that falls on a leaf into the
chemical energy in food. But that small percentage is enough; sunlight is
plentiful, and left to themselves, plants do not have to rely on any other
sources of energy to grow and produce.

Nevertheless, modern agriculture has managed to make food production an
energy-losing proposition. Its emphasis on increasing yield per unit of land
and per unit of human labor has meant a sharp increase in the input of fossil
energy-with farms often using more energy to produce the food than is
contained in the food. Some of the most notorious features of factory farming
are dark, dank hog and poultry confinement operations; now, Despommier's plan
would create plant-confinement operations as well.

Most of the attention that vertical farming has received in the media has
been embedded in the context of rooftop gardens, greenhouses, and "green"
high-rise facades (pdf). But those methods for growing modest amounts of
relatively expensive food (usually vegetables) differ from Despommier's plan
to "farm" the interiors of buildings in one important respect: they are at
least capable of capturing solar energy efficiently.

For obvious reasons, no one has ever proposed stacking solar photovoltaic
panels one above the other. For the same reasons, crop fields cannot be
layered one above the other without providing a substitute for the sunlight
that has been cut off. Even with all-glass walls, the amount of light
reaching plants on all but the top story of a high-rise would fall far, far
short of what is needed. (On a sunny day, a room with plenty of windows may
look well-lit to our eyes' wide-open pupils, but that light intensity is a
tiny fraction of what is needed for crop production.) A significant portion
of the light hitting the building would be turned back by the glass, and
direct sunlight would penetrate into the interior of a vertical farm only
when the sun is low in the sky (especially if, as Despommier recommends, two
layers of plants are stuffed into each story.) Even then, it would reach the
crop plants at a low angle, so that each square inch of leaf would receive
much less light than if the light were hitting the leaf from above.

As a result, the lion's share of a vertical farm's lighting would have to be
supplied artificially, consuming resource-intensive electricity rather than
free sunlight. This led us to wonder, "What would be the consequences of a
vertical-farming effort large enough to allow us to remove from the
landscape, say, the United States' 53 million acres of wheat?" That's not an
unreasonable question. In fact, it follows from Despommier's own reasons for
promoting the practice. He argues, correctly, that soil is currently being
abused on a massive scale; therefore, to address the problem, vertical
farming would need to displace agriculture from a large proportion of the
currently cropped landscape.

Our calculations, based on the efficiency of converting sunlight to plant
matter, show that just to meet a year's U.S. wheat production with vertical
farming would, for lighting alone, require eight times as much electricity as
all U.S. utilities generate in an entire year [see calculations here]. And
even if it were energetically possible, growing the national wheat crop under
lights could substitute for only about 15 percent of US cropland. Were it to
succeed, that energy buildup of unprecedented scale would still leave 85
percent of cropland in place.

Despommier suggests using renewable sources to supply the power needed for
vertical farming but fails to consider the scale-up that would be required.
Wind, solar, biomass, geothermal, and other renewable electricity sources
combined account for about 2% of U.S. generation. So to grow the national
wheat crop vertically using renewable sources would mean scaling up the
nation's renewable sector by 400-fold just to run the lights! (His proposals
for doubling plant density, using round-the-clock light, or pushing
year-round production, even if they could be made to work, would increase
production per unit of area but would not decrease the energy needed for
lighting per unit of food produced.)

One of our colleagues suggested, with his tongue in cheek, an alternative:
"What about vertical nuclear energy? We could stack reactors in skyscrapers
alongside the farming skyscrapers, to provide the electricity!" Fortunately,
no one's going to try that, because just to grow our wheat. we'd have to add
another 4000 or so nuclear reactors to the hundred or so currently in the
United States.

To have a much greater impact on soil conservation efforts than the
displacement of wheat would accomplish, we'd want to take indoors the
nation's number-one grain, corn, which occupies about a quarter of our
cropped acreage, and some of the most badly abused land. But corn makes
wheat's electricity consumption look modest. Because wheat naturally grows
mostly in fall, winter, and spring and produces lower yields than summer
crops like corn, its light requirement is lower. The U.S. corn crop would
require energy for lighting equivalent to 40 times the current US electricity
supply.

Maybe trying to satisfy the nation's huge grain requirements with vertical
farming is too ambitious. Assume instead that we were to take a more modest
approach and grow the national crop of vegetables under lights. If that
required a similar level of lighting per unit area to that used for wheat, we
would "only" have to double our national electricity generation. But removing
all vegetable production from the landscape would preserve no more than 2
percent of our currently cropped soils.

A question of control

Based on its energy requirements for lighting alone, vertical farming would
be incapable of substituting for a substantial share of our soil-based
agricultural production. But the lighting problem is only the first among
many obstacles facing high-rise agriculture. Climate control to achieve
suitable growing conditions would add huge energy requirements. And light
fixtures would release more energy as heat than as light, which in summer
would put huge loads on air-conditioning systems. To maintain the good health
of plants grown indoors, humidity and air circulation must be very precisely
controlled, often at a high energy cost. And before any of those needs would
come the gargantuan resource requirements for construction of the towers
themselves.

Then there would be the impracticalities and energy requirements for
producing and hauling artificial growth media, fertilizers, water, and other
resources hundreds of feet up and getting harvests out of the towers.
Pesticides could not be eliminated and would undoubtedly be applied in many
situations. If Despommier has ever worked in a greenhouse, he knows that some
of the pathogens and insects that damage crops in the field can be excluded,
but that many others will flourish. Powdery mildew, aphids, mites, or other
pests can easily wipe out greenhouse-grown wheat plants, for example, if
chemical control is not used.

The system inevitably would also require an enormous input of manual labor.
As a hydroponic model, Despommier points approvingly to 300-plus acres of
greenhouses near Willcox and Snowflake, Arizona, in which EuroFresh Farms
grows vegetables. Energetically, EuroFresh has no relevance to vertical
farming, because it is a horizontal operation that makes good use of Arizona
sunshine. But with four employees per cropped acre, it does provide a good
example of the large manual labor requirements of a massive, intensive
hydroponic operation.

EuroFresh's geographical location is no accident. It lies close to the
nation's southern border, and the company employs large numbers of immigrant
workers. It also employs inmates from a nearby branch of Arizona State
Prison. If EuroFresh is to provide an encouraging example for vertical
farming, other questions come to mind. Who will own and control the
agricultural high-rises? How and from where will the stoop-labor force for
vertical farming be recruited? What will become of the farm families whose
central role in the nation's life has been replaced by vertical-farming
operations? Will they find themselves migrating to the cities to tend
corporate tomato vines?

The EuroFresh greenhouses can also illustrate some of the pitfalls of
high-input indoor farming. In April, 2009, the company filed for chapter 11
bankruptcy, having fallen victim, according to the Arizona Daily Star, to
"its debt burden, labor troubles and crop pest problems," which included
invasions of white flies. (EuroFresh emerged from bankruptcy in November.)

Alternatives

The solution to soil and water degradation is not to strip food-producing
plants from the landscape only to grow them, deprived of sunlight, in
vertical factory farms. Instead, we have to address the Achilles heel of
agriculture itself: that it has displaced, on a massive scale, diverse stands
of natural perennial vegetation (such as prairies, savannahs, and forests)
with monocultures of ephemeral, weakly rooted, soil-damaging annual crops
such as corn, soybean, and wheat. So far, the weaknesses of the current
food-production system have been compensated for agronomically through
greater and greater inputs of fossil fuels and other resources, worsening the
ecological impact; vertical farming would extend that trend.

The landscape can be saved only through what we might call "three-dimensional
farming," a system that is arranged horizontally across the landscape to
capture and use sunlight but also puts down, deep, long-lived roots to
protect the soil, manage water, nutrients efficiently, and help restore the
below-ground ecosystems that agriculture has destroyed. That will require
converting cropland to the production of diverse, food-producing, perennial
crops. It will mean a reliance on natural processes and cohesive rural
communities, not technological fantasies.
Stan Cox and David Van Tassel are plant-breeding researchers at The Land
Institute in Salina, Kansas. Cox's book Losing our Cool: Uncomfortable Truths
about Our Air-Conditioned World, will be published in June by The New Press.
This article appeared in the Spring 2010 issue of Synthesis/Regeneration.






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