FYI,

"Could Vertical Farming be the Future? - Farm able to feed
50,000 people could 'fit comfortably within a city block'"
MSNBC
http://www.msnbc.msn.com/id/21154137

: Rice on the seventh floor. Wheat on the twelfth. And enough food
: within an 18-story tower to feed a small city of 50,000.

: Vertical farms, where staple crops could be grown in
: environmentally friendly skyscrapers, exist today only in
: futuristic designs an on optimistic Web sites.

: To Despommier, though, the world already has the need and the
: technology to dramatically improve yields and reliability by
: adjusting its point of view: from out to up.

: A recent exercise conducted by students in his medical ecology
: class found that a self-sustaining vertical farm able to feed
: 50,000 people could "fit comfortably within a city block," rising
: perhaps 18 stories. With adequate funding, a smaller prototype
: could be up and running in seven to 10 years, he predicts.
: Eventually, full-scale versions could be a new feature of city
: skylines, climbing as high as 30 stories and filled with automated
: feeders, monitoring devices and harvesting equipment. And, of
: course, they would feature crops such as wheat, rice, sugar beets
: and leafy greens grown in mineral nutrient solutions or without any
: solid substrates at all.

: These hydroponic and aeroponic growing techniques, respectively,
: have benefited from NASA's strong interest because any long-term
: venture to the moon or beyond would require the use of
: self-contained and resource-limited growth chambers. Despommier
: concedes that current practices must be improved and systems put in
: place to quickly identify and quarantine plants stricken with pests
: or disease. "No pun intended, but the bugs need to be worked out of
: this thing," he said.

: To his critics, that hurdle has tripped up past entrepreneurs and
: may yet be insurmountable. "I can't be very optimistic about this
: study," said Utah State's Bugbee. "None of this is very new. But it
: doesn't mean the whole concept is without merit. It just means the
: claims are greatly exaggerated."

: Bugbee's chief objection is the exorbitant power requirement for
: such a vertical structure. Plants on the lower floors would
: require artificial light year-round or expensive mechanical systems
: to get more light to them. And during a typical winter in northern
: U.S. cities, he said, average sunlight is only 5 percent to
: 10 percent of peak summer levels due to sapped intensity and
: shorter days.

: "November, December, January and February are really dark," Bugbee
: said. "Plants aren't limited by the temperature, they're limited by
: the light." High-pressure sodium lights may be a reasonable
: stand-in for sunlight to maintain plant growth, he said, but the
: electric bill is enormous. "Boy have a lot of people gone bankrupt
: trying hydroponic greenhouses for that reason."

: Nevertheless, greenhouses such as Arizona's 265-acre Eurofresh
: Farms are thriving with their hydroponic tomatoes and seedless
: cucumbers. Gene Giacomelli, Director of the Controlled Environment
: Agriculture Program at the University of Arizona in Tucson, said
: questions of safety, quality and sustainability are pushing
: agriculture in a host of other directions, including Despommier's
: vertical farming idea. "He's one extreme – a very good one,"
: Giacomelli said.

: Several years ago, Giacomelli and collaborators in Arizona explored
: another extreme when they won a contract to design and build a
: growth chamber within a new building at Antarctica's Amundsen-Scott
: Research Station. The chamber can be tweaked remotely by scientists
: back in Arizona but is now largely managed by volunteers at the
: station.

: Besides supplying some much-needed color and light for the research
: station's residents during Antarctica's bleak and bitterly cold
: winter months, the indoor chamber has yielded a range of crunchy
: greens, tomatoes, cucumbers, hot and sweet peppers and even
: cantaloupe. Next year, a student will try to grow watermelon in
: what is arguably the worlds' most inhospitable place for a garden.
: Remarkably, the plot has produced about two-thirds of what top
: greenhouses in North America can deliver.

: "I like to say that we can grow any plant anywhere and any time,
: but for a price," Giacomelli said. The catch in Antarctica is that
: electricity for the lights and pumps has inflated the cost to
: about $50 per pound of fresh vegetables . "Now, the local person at
: the supermarket would say you're crazy for spending that much money
: on vegetables," he said. "But you give that number to NASA and
: they'd say, `Wow, that's a good number.'"

: Despite a lack of major technological advances, the effort also
: stands to benefit from small but steady improvements in hydroponics
: and automated systems to control temperature, humidity and nutrient
: delivery, according to Giacomelli.

: To curb the excessive reliance on electricity, Giacomelli's own
: group is planning to experiment with fiber-optic tubes called solar
: pipes that can capture sunlight from the Antarctic growth chamber's
: roof. Meanwhile, Utah State University researchers have developed a
: clear piece of curved polyethylene that can retain heat in the
: ground and extend the growing season by up to four months for
: summer squash and tomatoes.

Mark Reiff