In the Great Plains, wind energy is cheap. Crazy cheap.
With the lowest levelized costs approaching $10 per megawatt-hour and thousands
of megawatts being procured for under $20 per megawatt-hour, PPAs for new wind
farms cost less than just the fuel required to run existing coal or natural gas
plants.
These economics have driven a wind boom in the region: renewable energy made
up three-fourths of the new capacity built in the Upper
Midwest in the last five years, and virtually all of the region’s active
projects in the MISO Interconnection Queue are wind and solar farms.
In the energy policy world, much ink has been spilled discussing solar’s infamous “duck curve.” But
while solar dominates in sunny California, in the Great Plains — which are blessed
with some of the best wind resources in the world — the lion’s share of
renewable generation comes from wind.
Will there be fearsome ducks to contend
with in wind-dominant regions, or will an entirely different animal appear in
windy regions?
Two days in the Upper Midwest last year provided a glimpse into life in a
high-wind future.
Renewables in the Upper Midwest
While California gets much of the attention when it comes to
renewables in the U.S., the Upper Midwest has comparable levels of renewable
generation. The region is peppered
with wind turbines.
In 2017, the MISO North Planning Zone — which includes Minnesota, Iowa, North
Dakota, and parts of Montana, South Dakota and Wisconsin — got 31 percent of its electricity from wind and small
hydro, compared to about 24 percent for CAISO as a whole.
At its peak in 2017, 67.6 percent of the generation in MISO North came from
wind and hydro, which is nearly identical to CAISO’s peak renewable production
of 67.3 percent.
The "smilin’ gator curve"
To see how high levels of wind generation affect the grid,
let’s take a closer look at the 2017 peak-wind day in MISO North. On October
24, 62 percent of the electricity generated in MISO North came from renewables
(almost entirely wind), topping out at 68 percent between 3 a.m. and 4 a.m. The
chart below shows how renewable generation (in gold) compared to electricity
use (in blue) throughout the day.
In short, there’s not much to see. Wind generation was quite stable throughout
the day. Recreating the duck curve shows that MISO North would not have faced
ramping issues, even with considerably higher amounts of wind generation.
In fact, the morning ramp on October 24 was actually less severe with
renewable generation than it would have been without. This was often the case
throughout the year: of MISO North’s most severe three-hour load ramps in 2017,
wind generation actually decreased the severity in eight of the top 10 ramps
(and two-thirds of the top 50).
So, if we’re not duck-like, what is the Upper Midwest’s energy mascot? We give
you: the smilin’ gator curve.
Unlike California’s ominous, faceless duck, Sally Gator welcomes the Midwest’s
commitment to renewable generation!
Does this mean there’s nothing to worry about when it comes
to integrating wind? Unfortunately, no.
Sally’s cheerful demeanor belies the challenges that lie ahead for
wind-dominant regions. Unlike solar, which ramps up and down as the sun rises
and falls, wind generation won’t have a consistent net load pattern like the
duck curve; wind’s net load curve will vary across weeks and throughout the
year. Another day later in 2017 provides a better illustration of the
challenges wind can pose.
While October 24 saw the highest percentage of wind generation on the MISO
North grid in 2017, renewables provided a bigger challenge to the grid on May
21 and 22. With the mild spring weather, electricity demand was relatively
flat throughout these two days, but wind generation varied dramatically. As a
result, the net load spiked late in the evening on May 21, fell sharply in the
overnight hours, and ramped up again in the morning of May 22.
This type of pattern could pose an even greater integration challenge than a
duck-like curve.
So, is this a frightening vision of things to come? Will adding more wind turn
the electric grid into a dangerous menagerie? No.
In reality, MISO weathered this storm with relative ease. Since the Upper
Midwest has made significant investments in transmission
infrastructure, surplus wind generation can be moved throughout the region as
needed.
On those days in May, imports and exports tempered the net load variability in
the region to the point where other generation resources were able to meet
demand with ease. Locational marginal prices at the Minnesota hub peaked at
just below 5 cents per kilowatt-hour on May 21 and just below 6 cents per
kilowatt-hour on May 22. For comparison, on July 6 — Minnesota’s peak
day in 2017 — LMPs averaged 8 cents per kilowatt-hour between 2 p.m. and 7
p.m., topping out at over 18 cents per kilowatt-hour.
Hegemonic renewables
At today’s penetrations, integrating wind generation — even
under the most trying circumstances — is manageable. Wind’s generation profile
tends to be steadier throughout the day than solar’s. Though there will be days
when wind creates even bigger integration challenges, these will be rarer and
will tend to occur during shoulder months when the grid has ample excess
generation capacity.
Still, deep decarbonization will require getting to dramatically higher
renewable penetrations, which will exacerbate challenges that are manageable
today. And this transition will happen faster than most realize: There are more
than 10 gigawatts of solar projects and more than 23 gigawatts of wind projects
in the region’s portion of the MISO interconnection queue.
Thanks to wind and solar’s complementary generation profiles, integrating
a combination of wind and solar will be easier than
either on its own. Moreover, geographic dispersion of renewables and advancements
in wind
turbine technology will further aid integration. And, as with
the duck curve, demand flexibility will become increasingly
valuable.
While renewables do pose integration challenges, grid operators can handle today’s
levels with relative ease. As renewable penetrations rise and challenges
intensify, utilities and ISOs will have many arrows in their integration
quiver. With proper planning, smart policy and market design can address these
challenges before they become crises. And the Upper Midwest will be able to
swap a pesky duck for a friendly gator.
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