History

2023
2023
WEIM tops $3 billion in benefits
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ISO Board of Governors and WEIM governing bodies adopt initiatives to establish an extended day-ahead market
Western Area Power Administration Desert Southwest region, El Paso Electric, and Avangrid join WEIM
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Real-time energy market reach expands to 11 Western states
More than 5,000 MW of battery storage now available
Ico battery
WEIM exceeds $4 billion in total benefits
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Major milestone: EDAM & DAME tariff filed with FERC
WEIM reaches $4.66 billion in benefits since start in 2014
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FERC accepts ISO tariff changes for Day-Ahead Market Enhancements (DAME) and the Extended Day-Ahead Market (EDAM)
5,660 MW of Clean Energy onboarded by the ISO in 2023
2022
2022
ISO releases first-ever 20-year Transmission Outlook
Avista Utilities and Tacoma Power join WEIM
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ISO hits all-time peak of more than 97% renewables
Ico renewables
WEIM surpasses $2 billion in benefits
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BPA and Tucson Electric Power join WEIM
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2021
2021
The Morongo Band of the Mission Indians becomes First Native American tribe to be a transmission owner in the ISO, connecting solar, wind, and battery resources to the grid
Ico renewables
ISO sets records in renewable energy integration
Continued to top renewable energy records in 2020, including historic peaks for solar and wind generation, and renewable energy serving load
Ico renewables
Turlock Irrigation District, BANC Phase 2, LADWP, Public Service Company of New Mexico, and Northwestern Energy join WEIM
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ISO Board implements shared-governance framework with WEIM Governing Body
Storage was the compelling story of 2021
2,359 megawatts (MW) of utility-scale battery storage capacity was added to our system in 2021, a key component to supporting grid reliability during the transformation to a carbon-free electric grid
Battery installation storage
2020
2020
Salt River Project and Seattle City Light join WEIM
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Historic wind generation peak of 5,318 MW on April 30
Ico wind
An historical peak of 81.8% of renewables serving load on May 2
Ico renewables
An historical solar generation peak of 12,016 megawatts (MW) on June 29
Ico solar
WEIM surpassed $1 billion in benefits
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Angelina Galiteva named first woman to chair ISO Board of Governors
2019
2019
Sacramento Municipal Utility District (SMUD), part of the Balancing Authority of Northern California (BANC) joined WEIM.
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ISO Reliability Coordinator Gains Regulatory Approval from NERC
Reliability Coordinator, RC West, Begins Operations
Official Reliability Coordinator of record for 16 electricity balancing authorities and transmission operators primarily in California, and one in Mexico.
RC West becomes Reliability Coordinator for 41 entities
2018
2018
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Announced plans to offer reliability coordination services
Idaho Power Company and Powerex joined Western Energy Imbalance Market
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198
Market participants
Ico participant
~22,000 MW
Renewables installed capacity
Ico renewables
~11,500 MW
Solar installed capacity
Ico solar 2023 06 24 171950 mpnm
~6,300 MW
Wind installed capacity
Ico wind
Launched webpage to track emissions from resources serving ISO load
Refined ISO processes smooth the path for energy storage participation
2017
Three-year anniversary of Western Energy Imbalance Market (WEIM) launch
Savings in WEIM surpassed a quarter billion dollars and reduced carbon emissions equivalent to eliminating 50,000 cars for a year.
2017
Portland General Electric joined WEIM
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10,000 MW
Solar installed, capacity reached in August
Ico solar 2023 06 24 171950 mpnm
Redesigned Today’s Outlook
Major overhaul of the ISO’s most-visited web page providing a central location for accessing key data.
2016
2016
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Lincoln, CA
Opened new secondary control center
Arizona Public Service and Puget Sound joined Western Energy Imbalance Market (WEIM)
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Board of Governors seated a permanent WEIM Governing Body
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Began tracking greenhouse gas emissions produced by resources serving ISO load
2015
NV Energy joined Western Energy Imbalance Market
2015
2014
2014
Launched the Western Energy Imbalance Market (WEIM)
The multi-state WEIM is a real-time market in which participants buy and sell excess power.
PacifiCorp joined WEIM
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2013
Back valley electric
January 1
Valley Electric Association joined the ISO balancing authority expanding the ISO footprint into Nevada.
2013
1.85 MW
First utility grade battery installed Vaca-Dixon Battery Storage (PG&E)
Ico battery
2011
2011
Oldnewcontrolroom
Control Center
ISO opened new headquarters with state-of-the-art control center.
Logo caiso current
The ISO logo was updated to depict its evolving role in shaping the future of renewable and advanced technologies
2009
2009controlroom
Launched new market and technology platform
The first non-capacity/integrated market that grew from three zones to nearly 5,000 nodes, increasing pricing transparency.
2009
28%
Wholesale energy costs
54%
Ancillary services expenses
The biggest RTO development of the year was the long awaited initiation of [California ISO’s] new market on March 31.
- Federal Energy Regulatory Commission State of the Markets Report 2009
300
Synchrophasers installed. Significant improvement in monitoring grid conditions and strengthening reliability.
Ico synchrophasers
2007
2007
Implemented the Location Constrained Resource Interconnection Program
Provided a mechanism to incentivize developers to build transmission in remoteareas.
2006
50,270 MW
All-time peak load July 24
2006
2004
2004
2004transnightsky
New Methods
Introduced the first-of-its-kind method to evaluate transmission projects based on economic benefits and reliability needs.
December 14
Gov. Arnold Schwarzenegger activated anew 500kV line between northern and southern California (Path 15), marking the first such state and federal partnership.
Governor path15
2002
Began integrating renewable resources
2002
2000
2000
The California electricity crisis
Helped the state navigate through the challenges posed by market manipulation.
1998
March 31
ISO operations commence with the first organized energy market.
1998
39
Market Participants
Ico participant
~3000 MW
Renewables installed capacity
Ico renewables
~230 MW
Solar installed capacity
Ico solar
~1,100 MW
Wind installed capacity
Ico wind
1996
1996
Logo caiso 1996 2023 07 25 183413 cxas
California was the first state to restructure its electricity market. The California ISO was formed.
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