POWER March 2017 - 58

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tion. " Conversely, higher system loads on
weekdays mitigate the midday decline in
net load and the impact of the duck curve. "
■ The duck curve doesn't occur just in
sunny spring months, as earlier analyses
had assumed. CAISO's 2013 analysis that
first identified the duck curve was based
on data for March 31. The ScottMadden
analysis found the steepest ramps in 2015
came in December, November, and January,
not March.
■ Utility solar, not rooftop panels, feeds the
duck. " If the belly of the duck is formed
by less visible distributed resources, " says
the report, " one would see it manifested
in both the system load and the net load.
This is not the case in the California duck
curve. Instead, we see a smooth system
load and a concave net load, which is indicative
of the influence of utility-scale
solar rather than distributed generation. "
ElectricityPolicy.com commented that, " it
appears the famous fowl known as the California
'duck curve' is developing a deeper
belly, with steeper ramping that will require
more flexible and fast-responding resources. "
Regional Balance
CAISO is leading the hunt for ways to slay
the duck, though the problem is not unique to
California (see sidebar, " Is California's Duck
Migratory? " ). In fact, Berberich sees the rapidly
developing regional energy imbalance
market as key. CAISO's energy imbalance
market is a voluntary, real-time wholesale
market offered to utilities in the region in
2014 as a way to coordinate their generation
and loads more broadly. Oregon's PacifiCorp
was the first participant.
The West has a surfeit of balancing authorities,
which isn't necessarily a good
thing. The EIA defines a balancing authority
as, " The responsible entity that integrates
resource plans ahead of time, maintains
load-interchange-generation balance within
a Balancing Authority Area, and supports
Interconnection frequency in real time. " The
western region has 38 different balancing authorities
by recent counts, and many analysts
view this as excessive and inefficient.
The idea behind the CAISO energy imbalance
market-which runs parallel to CAISO
but does not constitute a full-fledged regional
system operator-is to reduce the number of
balancing authorities in the region and make
the resources of various parties available to
each other with fewer jurisdictional seams.
Says Berberich, " A portfolio effect across a
larger region dampens overgeneration. Let's
share the overgeneration and leverage regional
generation. "
He adds that all of the states in the re58
2.
Quack up. Analysis by energy consulting firm ScottMadden last year suggests the duck
curve is growing faster than CAISO anticipated in 2013. Source: ScottMadden
■ 2011 ■ 2012 ■ 2013 ■ 2014 ■ 2015 ■ 2016
26,000
24,000
22,000
20,000
18,000
16,000
14,000
12,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
gion except Idaho " have some version of a
renewable portfolio standard. " That means,
the " more we collaborate across the region,
leaning on one another, we don't all have to
build new capacity. " The larger grid network,
centrally controlled, becomes a partial equivalent
to energy storage.
California's electricity market has undergone
several transitions over the past 25
years (see sidebar, " The Roots of CAISO " )
and seems poised for another as the CAISO
imbalance market expands. It has attracted a
growing list of non-California generating utilities
since Oregon's PacificCorp became the
first. The current roster includes Puget Sound
Energy in Bellevue, Wash.; Arizona Public
Service; Oregon's Portland General Electric;
Idaho Power; and Nevada's NV Energy. Last
October, the ISO said the benefits of the energy
imbalance market for the third quarter of
2016 exceeded $26 million, bringing the savings
since 2014 to $114.35 million.
CAISO late last year said two major California
public power systems-the Balancing
Authority of Northern California (which includes
the Modesto Irrigation District, City
Is California's Duck Migratory?
The duck curve may not be limited to California.
Greg Litra, the ScottMadden partner
watching over renewable energy issues,
said, " One of the most important implications
is the 'duck curve' may migrate to
other parts of the United States. Growing
numbers of utility-scale installations could
mean that 'the duck' could migrate to
states like Arizona, Georgia, Nevada, North
Carolina, and Texas in the not-too-distant
future. "
The ScottMadden analysis said, " Many
parts of the United States are poised for
market-driven growth in utility-scale solar.
For example, North Carolina is already expecting
solar to inject energy significantly
in excess of system needs by 2020. Additional
states to watch in the near term
include Arizona, Georgia, Nevada, and Texas.
Each of these states, including North
Carolina, may have more than 3,000 MW
www.powermag.com
of utility-scale solar by the end of 2021.
The duck may also appear in less obvious
environments, such as small balancing authorities
with high penetrations of utilityscale
solar. "
In Hawaii, where solar is a big resource,
the duck curve is less likely, as the state's
average system load " has changed over
time due to much higher penetrations of
distributed generation, notably residential
solar. In 2015, the 305 MW of residential
solar operating in the state was equal to
9% of the front-of-meter generation capacity
managed by Hawaiian Electric Company, "
the analysis found.
According to ScottMadden, comparing
California and Hawaii " illustrated that
understanding the root cause of the duck
curve is essential before preparing for and
developing strategies to address the operational
impacts. "
POWER | March 2017
MW
http://www.ElectricityPolicy.com http://www.powermag.com
POWER March 2017

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