IEEE Spectrum November, 2009 - 43
Yes,You Can Try This at Home
the r e sults of our exercise are as
A sustainable biofueled world, it turns
follows. Both the biofuel and solar sce- out, would require 32 times as much land
narios are carbon neutral by definition- and 14 times as much water as a solar
solar for obvious reasons, biomass world to meet a prosperous world's food
because carbon emitted in combus- and energy needs. In fact, a world enjoying
tion is reabsorbed when plants regrow. current U.S. levels of prosperity, fueled by
(Admittedly, biofuels are carbon neutral switchgrass, would require almost twice
only if crops are planted in existing tilled as much land and freshwater as are actufields and the emissions connected with ally available on Earth [see illustration,
fertilizer use, irrigation, and transpor- "Switchgrass vs. Photovoltaics"].
Biofuels provide around 6.5 megawatttation are left out of account. Analogous
hours per day per square kilometer.
qualifications hold for PV.)
I E E E S P E C T R U M P R E S E N TS :
The Robotics Continuum
A Four-part Webinar Series Sponsored by National Instruments
Webinar 4 * 12 November 2009
The Future of Robotics
The final webcast in this series will address one of the biggest challenges
in robotics; roboticists need powerful software to design their autonomous
systems. National Instruments is working hard to address this challenge and
provide an intuitive, I/O-integrated, open, flexible, and interactive software
environment for building autonomous systems.
T h at 's r ou g h ly e nou g h to p owe r
60 homes or carry 135 conventional
cars 50 kilometers (about 30 miles). A
photovoltaic system covering the same
square kilometer, with a typical commercially available system efficiency of
15.5 percent, could power 12 000 homes
or 60 000 electric vehicles. In this solar
scenario, cars powered by the internal
combustion engine are replaced with
electric vehicles that are three times as
efficient-a direct result of losses in the
henrik JonSSon/iStockPhoto
an interactive version of the model described here
is available at http://spectrum.ieee.org/energy/
renewables/energy-calculator. enter a chosen level
of prosperity for each area of the world, specify
how electricity will be generated and vehicles
moved, and voilà: You'll see how much land and
water is used and how much carbon is emitted.
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Manager, National Instruments
Register today at
www.spectrum.ieee.org/webevents
www.ieee.org/partners
SPONSORED BY:
52
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Table of Contents for the Digital Edition of IEEE Spectrum November, 2009
IEEE Spectrum November, 2009 - Cover1
IEEE Spectrum November, 2009 - Cover2
IEEE Spectrum November, 2009 - 1
IEEE Spectrum November, 2009 - 2
IEEE Spectrum November, 2009 - 3
IEEE Spectrum November, 2009 - 4
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IEEE Spectrum November, 2009 - 8
IEEE Spectrum November, 2009 - 9
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IEEE Spectrum November, 2009 - 30
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IEEE Spectrum November, 2009 - 32
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IEEE Spectrum November, 2009 - 34
IEEE Spectrum November, 2009 - 35
IEEE Spectrum November, 2009 - 36
IEEE Spectrum November, 2009 - 37
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IEEE Spectrum November, 2009 - 39
IEEE Spectrum November, 2009 - 40
IEEE Spectrum November, 2009 - 41
IEEE Spectrum November, 2009 - 42
IEEE Spectrum November, 2009 - 43
IEEE Spectrum November, 2009 - 44
IEEE Spectrum November, 2009 - 45
IEEE Spectrum November, 2009 - Cover3
IEEE Spectrum November, 2009 - Cover4
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