There is enough energy available in winds to meet
all of the world’s demand. Atmospheric turbines that convert steadier and
faster high-altitude winds into energy could generate even more power than
ground- and ocean-based units. New research from the Carnegie Institution of
Science’s Ken Caldeira examines the limits of the amount of power that could be
harvested from winds, as well as the effects high-altitude wind power could
have on the climate as a whole. Their work is published in Nature Climate
Change.
Led by Kate Marvel of Lawrence Livermore National
Laboratory, who began this research at Carnegie, the team used models to
quantify the amount of power that could be generated from both surface and
atmospheric winds. Surface winds were defined as those that can be accessed by
turbines supported by towers on land or rising out of the sea. High-altitude
winds were defined as those that can be accessed by technology merging turbines
and kites. The study looked only at the geophysical limitations of these
techniques, not technical or economic factors.
Turbines create drag, or resistance, which removes
momentum from the winds and tends to slow them. As the number of wind turbines
increase, the amount of energy that is extracted increases. But at some point,
the winds would be slowed so much that adding more turbines will not generate
more electricity. This study focused on finding the point at which energy
extraction is highest.
Using models, the team was able to determine that more
than 400 TW of power could be extracted from surface winds and more than 1,800
TW could be generated by winds extracted throughout the atmosphere.
Today, civilization uses about 18 TW of power.
Near-surface winds could provide more than 20 times today’s global power demand
and wind turbines on kites could potentially capture 100 times the current
global power demand.
At maximum levels of power extraction, there would
be substantial climate effects to wind harvesting. But the study found that the
climate effects of extracting wind energy at the level of current global demand
would be small, as long as the turbines were spread out and not clustered in
just a few regions. At the level of global energy demand, wind turbines might
affect surface temperatures by about 0.1 C and affect precipitation by about
1%. Overall, the environmental impacts would not be substantial.
“Looking at the big picture, it is more likely
that economic, technological or political factors will determine the growth of
wind power around the world, rather than geophysical limitations,”
Caldeira says.
Source: Carnegie Institution of Science
