Solving wind power’s variability with more wind power
by John Farrell.
This post originally appeared on Energy Self-Reliant States, a resource of the Institute for Local Self-Reliance’s New Rules Project.
One solution to the variability of wind power is more wind.
The
output from a single wind turbine can vary widely over a short period
of time, as wind goes from gusty to calm. The adjacent graphic (from this report [PDF])
illustrates how a single turbine in Texas provided varying power
output over a single day, varying from under 20 percent of capacity to
near 100 percent!
But the same report also illustrated the smoothing effect when the
output from these five wind sites was averaged. The following chart
shows (in dark orange), the smoothing effect of output when the wind
output was averaged over five sites.
The impact is significant, and the optimized system varies from 15 to
50 percent of capacity, compared to individual turbine variability
that’s twice as large. Over a longer period (a year), the optimized
(combined) system provides significantly more reliable power to the
electric grid. It reduces periods of zero output to a few hours per
year, effectively zero probability.
Combining the output of the five sites also increases the probability
that the output will be at least 5 percent or 10 percent of total capacity of the
wind turbines.
Other studies have reinforced these findings. For example, a report [PDF] by Cristina Archer and Mark Jacobson in 2007 found that dispersing wind
at 19 sites over an area the size of Texas increased the level of
guaranteed output by four times.
Wind power could not be the sole source of electricity for the grid
without massive overbuilding of capacity, but its variability is an
argument for more dispersed wind, rather than less of it.
Related Links:
The EV-hater’s guide to hating electric cars
IKEA to go 100 percent renewable, starting with 67 wind turbines
Buy an electric car, get a steep discount on the rooftop solar panels required to charge it
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