About Us > What We Do > Our Three Critical Roles

Power System

Managing the regional power system planning process is one of three critical roles the ISO performs in New England.

Ensuring the Power System Evolves to Meet Future Electricity Needs

To effectively oversee the movement of high-voltage electricity into, within, and out of New England, the ISO must make certain that the region has the power resources and transmission lines necessary to meet the demand for electricity over time. We do this by performing comprehensive system analysis and planning—and sharing that information with the marketplace to signal where new investment is needed. Because the ISO is not-for-profit, independent, and does not favor one resource over another, we coordinate, evaluate, and oversee these types of power system additions objectively.

New England relies first and foremost on projects proposed from the marketplace to solve power system needs—in other words, private investment in new power plants, transmission facilities, and other resources. If market responses are not forthcoming or adequate to meet New England’s needs, the ISO, in its role as Regional Transmission Organization, is required to facilitate a competitive process for ensuring the development of transmission infrastructure solutions that are essential for maintaining power system reliability and an efficient wholesale electricity marketplace, or for meeting public policy goals set by federal, state, and local governments. (See Attachment K, Regional System Planning Process, Section 4.2, Treatment of Market Responses and Evaluation of Regulated Transmission Solutions, of the Open Access Transmission Tariff.)

Learn what we mean by system reliability.

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Planning Provides Information to the Marketplace

To meet future system needs, the ISO’s planning process must consider many different factors, such as the likelihood of power plant retirements, the expected development and integration of the region’s renewable resources, the impact of public policies on the grid, and the close interaction between the natural gas and electric power systems.

Through the ISO’s regional system planning process:

  • We conduct ongoing engineering assessments that analyze and estimate New England’s power system requirements, typically looking 10 years or more into the future.
  • We identify electricity consumption patterns and growth; adequacy of resources to meet demand; and issues related to power plant fuel supplies, fuel diversity, environmental requirements, and integration of new technologies.
  • We also respond to requests for economic analysis of various resource‑expansion scenarios.

This continuous process yields a biennial Regional System Plan (RSP) that serves as a roadmap of system needs. The power system is never static, so we update the RSP to reflect the latest system conditions, forecasts, and investments in the power system. See key stats on transmission investment in New England and related data.

All this information, combined with pricing signals from the markets, enables participants in the marketplace to make sound business decisions about investing in the power system—investments which help ensure the reliable flow of electricity. Informed decision making is critical to participants who, in New England’s market-based environment, carry most of the financial risk of these large-scale investments.

The RSP also includes a plan for coordinating a regional response to any additional transmission infrastructure improvements needed to maintain reliability and an efficient wholesale electricity marketplace, or for meeting public policy goals set by federal, state, and local governments. These are considered “regulated transmission solutions.”

transmission projects

Transmission Infrastructure Investment: Shared Costs and Benefits

Continuously improving the transmission system has benefitted New England in many ways—from reducing the risk of blackouts to decreasing air emissions and lowering energy costs. (See our Key Stats on transmission investment.) However, making improvements to the transmission system has many challenges:

  • Transmission is expensive to build.
  • Construction requires long lead times.
  • Proposed locations for lines and substations often face opposition.
  • Projects involve numerous decision makers.

New England has been successful in developing new transmission infrastructure for two main reasons:

  • Our planning process is conducted through an open, public forum that includes input from all sectors of the industry, plus government representatives from the six New England states. Having state regulators involved in the process enables them to make informed, sound decisions about whether and where lines will be constructed. (Read more about the ISO’s stakeholders and regulators.)
  • The region has a well-defined funding mechanism that provides the financial certainty for regulated transmission solutions deemed essential for maintaining power system reliability, improving market efficiency, or satisfying public policy goals. The costs of these transmission projects are shared by consumers across the region on the principle that all consumers benefit when the reliability of the highly interconnected regional network is improved. Learn more about how the ISO identifies system needs and runs the process to find competitive solutions.

Regional electricity demand by state

How Are Transmission Costs Allocated?

For regulated transmission solutions to meet identified reliability or market efficiency needs, costs are allocated across the region on a load-ratio basis—in other words, it’s based on the amount of electricity demand in each state. For public policy projects or interregional transmission facilities, a different cost allocation is used. Learn more.

The cost for projects proposed by the marketplace that are not deemed essential for power system reliability are typically borne by private investors and not eligible for regional rate recovery, just as they are for power plant and other resource development. Such projects are called elective transmission upgrades.

To learn more about the ISO’s responsibilities and process for deciding whether the region will share the costs for new transmission, see the Transmission Cost Allocation page.

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Connecting to the Grid

ISO New England has other responsibilities in coordinating how transmission lines, power plants, and other resources connect to and operate on the grid. For example:

  • We review and approve all proposed transmission system changes because they may impact the stability, reliability, or operating characteristics of New England’s power system.
  • For transmission projects that qualify for regional rate recovery, we review all costs. Along with deciding whether regional cost support is justified, we consider whether costs are reasonable and in accordance with good utility practice.
  • We administer the complex process for adding new power plants and power plant upgrades to the grid. Through extensive engineering studies, we determine whether interconnecting a proposed plant to the tightly integrated system would be feasible without adversely affecting reliability and how this should be done.
  • We also monitor plant construction schedules to ensure that resources are placed in service in time to meet the identified need.

Our Interconnection Request Queue report is continuously updated to reflect newly proposed resources, projects that have been withdrawn, and projects that have begun commercial operation. See key statistics on proposed resources.

As part of the region’s capacity market, the Forward Capacity Market (FCM), we also:

  • Have a team study and determine which generation and demand-resource proposals are qualified to participate in each annual capacity auction
  • Monitor the construction and development process of resources selected in the auction to ensure they will be on line by the commitment date

Registration and Performance Auditing

For the ISO to have a clear understanding of the capabilities of each asset on the grid, all resources on the power system must be registered with us. Each year, we process thousands of registrations and updates for new and existing power plants, load assets, tie lines, demand-resource assets, and designated entities (the entity designated by a market participant to receive ISO dispatch instructions). The ISO also conducts hundreds of audits each year to evaluate the capability and performance of resources to ensure they are able to operate as expected.

To help promote reliable operation and successful participation in New England’s marketplace, we also provide extensive training opportunities for new and existing resource owners.

The ISO’s Other Critical Roles

Learn about the ISO’s other two key roles in New England’s electricity industry:

Key Grid and Market Stats