IEEE Power & Energy Magazine - March/April 2022 - 80

are needed before the growing reliance
on variable resources impacts
system reliability.
Resilience: Preparation
for Extreme Weather
High-impact weather events are no
longer infrequent. The average number
of extreme weather events in the
United States causing more than US$1
billion in damages has increased from
2.9 per year in the 1980s to 16 per
year in 2016-2020. The average annual
cost of these events has increased
from US$17.8 billion to US$126 billion
per year. The number and severity
of extreme weather events have
increased with
✔ the increasing intensity and
slower postlandfall weakening
of hurricanes. For example, Hurricane
Ida took out the transmission
lines serving New Orleans
and brought down power lines
and flooded streets and basement
apartments, killing 56 people
in four northeastern states.
✔ the increasing frequency and
intensity of other extreme precipitation
events, i.e., tornados,
hailstorms, and floods.
✔ increases in the frequency, duration,
and geographic scope
of heat waves. For example,
the June 2021 Pacific Northwest
heat dome increased temperatures
in Seattle to 109° F,
Portland to 116°, and towns in
eastern Washington and British
Columbia to above 120°.
✔ severe drought conditions across
nearly 90% of western states,
shrinking reservoirs at Colorado
River dams and reducing hydroelectric
power in California by
38%.
✔ elevated wildfire risks that require
de-energizing transmission
lines in fire-prone areas
✔ large areas of unusually cold winter
temperatures. For example, Winter
Storm Uri in February 2021 caused
61.8 GW of unplanned generator
outages and 23.4 GW of firm
load shedding.
80
ieee power & energy magazine
Climate models suggest that the frequency
and severity of extreme weather
events are likely to increase. Some
extreme events, such as the Northwest
heat wave, now considered to be a onein-1,000-year
event, will be beyond
what can be predicted from available
data. Climate conditions are already
well outside the range of human experience.
The average atmospheric concentration
of carbon dioxide in 2020
was 37% higher than the highest levels
in the 800,000 years before 1900. Extreme
weather causes common mode
failures: widespread demand increases
during heat waves and cold-weather
events, unplanned outages at multiple
generating units, interrupted fuel supplies,
damage to multiple transmission
lines, and distribution outages.
Conventional resource planning
systematically understates the probability,
depth, and costs of such events.
Generator outages are often assumed
to be independent, uncorrelated events.
Standard resource adequacy metrics
are based on expected values, limiting
the weight and attention given to
high-impact events that are infrequent
in the historical data. Moreover, societal
and customer outage costs are not
included in North American Electric
Reliability Corporation's standard reliability
risk metrics.
A January 2021 Electric Power Research
Institute report, for which I was
one of the principal investigators, described
the limitations of current practices
and a set of steps for developing
stochastic resource adequacy models
that include high-impact events and
value-of-load-at-risk metrics-comparable
to financial value-at-risk metrics.
Such models and metrics will enable
planners and regulators to evaluate
risk-the likelihood and cost of disruptive
events-and to compare different
options that could avoid or mitigate the
impacts of these events. The report also
includes recommendations to improve
natural gas data reporting, create a gas
reliability organization comparable to
North American Electric Reliability
Corporation, and enhance coordination
of gas and electric markets to reduce
the uncertainty of natural gas supplies
when gas systems are stressed.
Probabilistic weather forecasts
can identify more than a week in advance
the risk of weather conditions
that could disrupt the power system.
We are working with an ISO and a
weather forecasting organization to use
granular, probabilistic weather forecasts
to develop locational reliability
pricing. This work on stochastic nodal
adequacy pricing is being supported
by the U.S. Advanced Research Projects
Agency-Energy. It could improve
existing scarcity pricing mechanisms
and provide risk-based price signals,
enabling consumers and resources, including
DERs, to prepare for extreme
weather. A broader, risk-based reliability
component in short-term prices
would be reflected in forward contracts
and help support investment in the resources
best able to mitigate weatherrelated
risks.
Adding resources and hardening assets
is insufficient for minimizing the
impact of extreme events. More frequent,
extreme weather requires creating
more resilient systems. Resilience
differs from resource adequacy and
reliability. It focuses on high-impact,
region-specific risks, including longduration
and wide-area power outages,
and events that degrade other critical
systems. Resilience requires working
with public and private partners
to maintain critical services during
extreme events and the restoration of
normal operations. It assumes extreme
events will degrade power system capabilities
and focuses on how utilities
and their partners can manage during,
recover after, and incorporate lessons
learned from such events.
DERs can contribute to the development
of a more resilient power system.
In this issue of IEEE Power & Energy
Magazine, Reid et al. cite the example
of developing microgrids to support
community centers and libraries in San
Francisco. Such facilities are needed to
provide support services when major
outages happen. An urban area power
outage that coincides with a heat wave
could leave hundreds of thousands
march/april 2022
IEEE Power & Energy Magazine - March/April 2022

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