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May 2018  •   Issue 13
The ISO is a nonprofit public benefit corporation that manages the bulk electric market, and the flow of electricity over the high-voltage, long-distance power lines for California and a small part of Nevada.

California Legislature considers regional energy marketplace


On Jan. 3, 2018, the state Legislature began the second year of its two-year session, and State Assemblymember and chair of the Utilities and Energy Commission, Chris Holden, amended AB 813, legislation that would create a path to a western states electric system and market.

ISO studies have shown the development of a regional energy market would be the quickest and most cost-effective way to meet ambitious state renewable energy goals. The ISO’s studies, called for under the 2015 Senate Bill 350 legislation, showed that a regional market would save ratepayers as much as $1.5 billion a year by 2030, create thousands of jobs, and reduce air pollution.

As a worldwide leader in incorporating renewable energy into its grid, the ISO is committed to finding ways to maximize clean energy resources while maintaining a reliable electric system.

Click here to learn more about the potential benefits of a regional ISO. An informational video on the subject is also available here.

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The California ISO turns 20 years old


On March 31, 1998, the California Independent System Operator began operating the high-voltage grid and delivering energy to millions of consumers in what was then the world’s seventh largest economy. The ISO has since become a recognized leader in using zero-carbon resources and reshaping what was a static, inflexible power generation and delivery system into a modern, clean grid.

The grid in 1998 had about 230 megawatts of solar resources, 1,100 megawatts of wind and about 3,000 total megawatts of renewable resources, including geothermal energy. Today we manage over 11,000 megawatts of solar, 6,300 megawatts of wind and nearly 22,000 total megawatts of green, low-cost resources serving electricity demand.

An important ISO accomplishment occurred in 2009 when a new market platform was launched that prices power at its point of generation and delivery, thus providing transparency into costs at over 5,000 nodes on the grid; now the ISO has about 6,000 nodes.

The ISO also introduced in 2014 the western Energy Imbalance Market, a real-time market that utilities outside of California can use, which now serves consumers in eight western states and has saved over a third of a billion dollars for its participants.

Click here to visit the new 20th anniversary webpage.

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Western EIM welcomes two new participants


After many months of preparation, two new participants, Boise-based Idaho Power and Powerex of Vancouver, British Columbia, entered the western Energy Imbalance Market (EIM) on April 4.

The EIM now serves more than 42 million consumers on a power grid stretching from the border with Canada south to Arizona, and eastward to Wyoming.

Idaho Power brings a robust portfolio of 17 hydroelectric plants to the market, while Powerex is able to leverage the significant hydroelectric assets and transmission capacity of its parent company, BC Hydro.

The new entries raises to eight (seven entities, plus the ISO) now active in serving about 55 percent of the total load in the West. The market has used more than 520,330 megawatt-hours of mostly excess solar energy since its 2014 launch that otherwise would have been turned off. That’s enough energy to power about 58,000 average homes for one year. Through March 2018, the EIM has saved $330 million dollars. Read more about the western EIM here.

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ISO Transmission Plan looks 10 years ahead


Running the electric grid may be the most visible of the ISO’s responsibilities, but the ISO also conducts a comprehensive transmission plan to identify system infrastructure needs for the next decade.

More than a dozen highly-trained ISO transmission engineers spend 15 months performing sophisticated analysis to determine what infrastructure is required to serve future electricity needs. The first step in the plan is to work with utilities, regulators, generators and other stakeholders to agree on the study inputs, which are built using data provided by the California Public Utilities Commission and the California Energy Commission, including expected demand growth and weather scenarios.

The inputs also include the potential impact on the grid from contingencies, or reliability events, and it is determined what is needed to maintain reliability if a transmission line is lost or a generator goes offline, or both at the same time. Transmission engineers also study California by “local capacity” areas, which are geographic areas that are electrically related, such as sharing high-voltage transmission lines. See figure 1 below.

geographic image 

       Figure 1.

Other factors considered include local power plant retirements and additions, and confirmation of the area’s power lines ability to carry energy to consumers. The local capacity studies reflect the minimum resource capacity needed to meet the energy needs of the area, with near-term, mid-term and long-term analysis that looks out two to 10 years. The bulk of the data is publicly available.

Once local needs are determined, the utilities begin the state regulatory process to build any upgrades needed for reliability, while economic projects are open for competitive solicitations to get the best, lowest-cost proposal.

The ISO grid has grown from about 12,500 miles of transmission in 1998 to nearly 26,000 miles; 3,000 megawatts of clean, renewable resources to over 20,000 megawatts; and about 800 generation units to over 1,900 units. Learn more about us at

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