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How Reliability Needs are Identified on New York’s Grid

July 14, 2023

For some time now, the NYISO has been reporting on declining reliability margins on New York’s grid, noting that New York City, in particular, is at increased risk of outages as soon as 2025. On July 14, 2023, we published the findings from our second quarter 2023 Short-Term Assessment of Reliability (STAR) report. We found that through updates to our analysis margins in New York City disappear altogether in summer 2025. This required us to declare a “reliability need” in order to avoid outages and disruptions to New Yorkers’ power supply. But, how does the NYISO identify these types of concerns?

First, when the NYISO examines and identifies reliability needs, we’re analyzing what’s known as the transmission system in the state. This is the system that generates and delivers power to the local distribution systems operated by utilities. The NYISO and the uiltities are responsible for the transmission system being able to serve demand across the state at all times. When we forecast that it won’t be capable of doing that, it’s because we anticipate that there won’t be enough generation or transmission capability available to the system. Under these circumstances, we declare a reliability need and work with utilities, stakeholders, and developers to resolve it.

Planning for Reliability

At the heart of reliability planning is the demand forecast, or how much energy we expect New Yorkers to require in the future. Forecasting future demand on the grid often begins by looking at economic data and forecasts, historical data, demand forecast data from local utilities, and anticipated weather and climate conditions to understand how much electricity will need to be supplied. For instance, air conditioning is largely responsible for driving summer peak demand in New York. As temperatures rise, air conditioning demand increases, and historical data helps the NYISO understand what level of demand can be expected at different temperatures as a result. To support reliability planning, the NYISO develops ranges of load forecasts to reflect risks in future years due to uncertainties in such factors as population and economic growth, and the adoption of new technologies such as electric vehicles and heat pumps.

Once the demand forecasts are established, the next step is to determine whether the grid has enough supply and transmission capability to meet the demand. That involves assessing the historical performance of generators, identifying generator additions, generator retirements, transmission upgrades, and other anticipated changes to the makeup of the grid. Carefully crafted rules of inclusion guide NYISO planners in identifying when generation or transmission developments achieve a level of certainty such that they can be counted on for maintaining system reliability in the future.

For example, a proposed generator that hasn’t made significant progress in the financing, permitting, or construction or hasn’t advanced sufficiently through the NYISO’s interconnection study process may not be included in the baseline reliability plans due to the risk and uncertainty associated with the project’s successful completion. Projects eligible for inclusion in the reliability planning process are included in plans based on when they are expected to enter service. In this manner, the reliability planning process seeks to anticipate the supply resources and transmission infrastructure available to meet forecasted demand in order to determine if reliability concerns or violations arise.

Reliability Rules

Mandatory reliability rules are designed to promote and preserve the reliability of the transmission system by, among other things, providing protection for from widespread and cascading outages. They establish the criteria to which the grid must be planned and operated in order to attain the desired level of reliability. The rules to which the NYISO must plan for require a level of redundancy in grid operations such that reliability can be maintained even if key elements of the grid are not available. This is accomplished by studying the grid’s performance under expected conditions, then re-examining its performance under certain contingency conditions, such as generator or transmission outages, to determine if such events can be managed without impacting reliability.

New York’s reliability rules have been refined over time. Informed by past events, New York’s rules reflect a recognition of the critical health and safety aspects of grid reliability, particularly in New York City where high demand and transmission limitations require local generation to be available.

Anticipating a Reliability Need

NYISO’s previous reliability assessments have been showing thinning reliability margins, but identified no violations that would result in declaring a need. However, updated forecasts show demand growth in New York City that is more reminiscent of pre-COVID growth, with increased economic activity. Demand is also growing on the strength of electrification initiatives that are placing new demands to the grid. At the same time, supply resources in New York City are retiring, requiring greater reliance on transmission to meet its needs.

The NYISO’s second quarter 2023 Short-Term Assessment of Reliability (STAR) report showed that the growth in demand coupled with the retirement of generators is leading to declining reliability margins statewide but will result in a deficient in the margin for New York City in summer 2025 based on an updated load forecast. The second-quarter STAR report, therefore, identified a reliability need associated with transmission security violations that could introduce outages in New York City. To avoid that situation, we’ll be working with Consolidated Edison Company of New York, Inc. (Con Ed) and stakeholders to identify solutions that will maintain reliability to support the public health and safety of all New Yorkers.