POWER July 2021 - 8

GLOBAL MONITOR
THE BIG PICTURE: Reserve Margins
The North American Reliability Corp. (NERC) this May warned large swathes of North America are at elevated risk to experience energy
emergencies this summer due to higher temperature-dependent loads and potential supply shortfalls. As shown here, NERC's Anticipated
Reserve Margin is based on available resource capacity (commercially operable generators with firm capacity). The metric is used to evaluate
resource adequacy by comparing the projected capability of anticipated resources to serve forecasted peak demand. The Reference Margin
Level essentially serves as a threshold used by system operators to determine the necessary reserve capacity to ensure sufficient supply to
meet peak loads. While all assessment areas have sufficient Anticipated Reserve Margins to meet or exceed their Reference Margin Level for
summer 2021, in some regions-especially in California and Texas-conditions may tighten if the system experiences high resource outages
and high demand. Notes: ISO = Independent System Operator; MRO = Midwest Reliability Organization; NPCC = Northeast Power Coordinating
Council; SERC = SERC Reliability Corp.; WECC = Western Electricity Coordinating Council. Source: NERC 2021 Summer Reliability Assessment
-Sonal Patel is a POWER senior associate editor.
0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%
MRO:
Midcontinent ISO (MISO)
Manitoba Hydro
Saskatchewan
Maritimes
NPCC:
ISO New England (ISO-NE)
New York ISO (NYISO)
Ontario (IESO)
Québec
PJM Interconnection
East
SERC:
Central
Southeast
Florida Peninsula
Southwest Power Pool (SPP)
Electric Reliability Council of Texas (ERCOT)
WECC:
California/Mexico
British Columbia
Alberta
Northwest Power Pool and
Rocky Mountain Reserve Sharing Group
Southwest Reserve Sharing Group
8
ERCOT anticipates record-breaking demand of 77.1 GW-more than 2 GW above
its current demand record. But, it warned, a combination of factors in real-time,
including record demand, high thermal generation outages, and low wind/solar
output could result in " tight grid conditions. " The grid operator experienced tight
conditions on June 14, when nearly 10 GW of thermal generation reported
forced outages.
ISO-NE expects 31 GW of available capacity compared to an above-average
summer peak demand forecast of 26.6 GW. NERC projected above-normal
summer peak load and outage conditions could result in the need to employ
operating mitigations.
Anticipated Reserve Margin
Reference Margin Level
While MISO in May projected 122 GW with 146 GW of available capacity,
NERC said summer scenarios with high resource outages and high demand
may require the use of load modifying resources (LMRs) and non-firm
imports during peak periods.
California ISO, which shed load in August 2020, anticipates better supply
conditions this summer, " but continues to see potential challenges in meeting
demand during extreme heatwaves. " NERC went further, suggesting
above-normal peak load would cause area resource shortages during periods
of peak demand and extend into evenings as solar PV output diminishes
while demand remains high. High thermal resource outages or reduced
availability of imports associated with extreme or wide-area heat events are
likely to result in firm load-shed, it said.
WECC said the NWPP-C subregion-an area that includes Colorado, Idaho, Montana,
Oregon, Utah, Washington, and Wyoming-is expected to peak in mid-July at about
36.4 GW. But though it expects peak resources of 42.4 GW, under low availability
conditions, the NWPP-C subregion may only have 30.5 MW available. NERC suggested
extreme summer peak load and outage conditions could result in operating mitigations.
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POWER July 2021

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