Grid Glossary

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Critical Issue Fast Path (CIFP)

An accelerated stakeholder process used in PJM Interconnection to resolve urgent, contentious, and time-sensitive issues that cannot be resolved through the normal stakeholder process. The process involves several stages of discussion and proposal development, culminating in a submission to the Federal Energy Regulatory Commission (FERC) for approval. The CIFP process has been used in recent years to discuss large load additions (2025) and resource adequacy (2023).

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Effective Load Carrying Capability (ELCC)

Measurement used to calculate how much an energy resource–such as a wind farm or solar array–contributes to the overall reliability of the grid. It assesses the resource’s ability to meet electricity demand, particularly during peak usage periods, and is especially useful for variable renewable energy sources whose output depends on factors like weather conditions. 

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Disturbance

Refers to any unwanted or unplanned electrical event that interferes with the normal operation of the electrical grid. These can manifest in power outages, surges, and other events, and can originate from various sources within the electrical grid, such as loss of a large generating unit or another grid asset, such as a transmission line or transformer.

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202(c) Order

An emergency order issued by the United States Department of Energy (DOE) under Section 202(c) of the Federal Power Act. It allows the Secretary of Energy to temporarily order connections of facilities and the generation, delivery, or transmission of electricity to best meet an emergency caused by war, a sudden increase in demand, or a shortage of energy or facilities. These temporary orders can also exempt power plants from federal, state, or local environmental rules and have historically been used to prevent outages during severe weather events or supply shortfalls.

Active power

Also known as real or true power, is the portion of electrical power that does useful work in a circuit, such as generating heat, light, or mechanical energy. (see related: reactive power)

Advance Notice of Proposed Rulemaking (ANOPR)

A preliminary document used by government agencies to solicit public feedback on potential new rules or reforms before they are officially proposed. It outlines initial ideas, asks specific questions, and serves as the first step in a larger regulatory process. The acronym is frequently used by the Federal Energy Regulatory Commission (FERC). It precedes a formal Notice of Proposed Rulemaking (NOPR) and allows agencies to gauge public opinion and gather information to develop a more informed proposal.

Ancillary services

(see also: Essential reliability services) – Supplementary services essential for maintaining the reliable operation and stability of the electrical grid beyond the basic generation and transmission of energy. They are “behind-the-scenes” services that include real-time balancing of electricity supply and demand, maintaining voltage levels, and providing the capability to restart the grid after a widespread outage (black start). 

Automatic Generation Control (AGC)

Is an automated system that continuously monitors the electrical network and adjusts the power output of multiple generators. Its primary functions are to maintain system frequency (60 Hz in United States), in response to changes in the power demand, or load.

Baseload

The minimum amount of electricity that a utility must provide to meet the consistent, ongoing needs of its customers. Historically, this steady demand was met by large power plants (like coal or nuclear) that ran continuously. Today, with more renewable energy, this minimum demand can be met by a flexible mix of various power sources, rather than relying solely on specific “baseload plants”.

  • Baseload capacity:  The generating equipment normally operated to serve loads on an around-the-clock basis.
  • Baseload plant:  A plant, usually housing high-efficiency steam-electric units, which produces electricity at an essentially constant rate and runs continuously. 
Battery Energy Storage System (BESS)

A technology that stores electrical energy in rechargeable batteries for later use. Batteries help stabilize the grid, manage energy demand, and increase the use of renewable energy.

Behind-the-meter

Any energy resource that provides energy directly to a home or business without passing through a utility company’s meter. Examples include rooftop solar and microgrids.

CAISO

California ISO

Capacity

The maximum amount of power an energy source can physically produce (measured in megawatts/MW), or when referring to an electrical grid, the total amount of electricity that power plants connected to the grid are capable of producing. It’s essentially the total potential output of all the electricity sources, like coal, nuclear, hydro, wind, and solar plants. Meanwhile, energy is the actual output of a source over a particular time period. 

  • Capacity accreditation – The process by which grid operators determine the reliability contribution of individual power resources (such as power plants or energy storage systems) to the overall electricity grid. It quantifies how much a resource can reliably contribute to meeting demand, especially during peak times or periods of tight supply, guiding investment decisions for grid stability.
  • Capacity auction – A competitive market mechanism where grid operators or utilities purchase energy in the market from electricity generators (such as coal plants, wind, and solar farms) or demand-response participants for future energy needs. Essentially, the generators or demand-response entities provide their energy or technology for future periods of high demand. Capacity market auctions ensure enough electricity is available for future demand at the lowest achievable price for consumers. The goal is to balance reliability with cost by having market participants compete. There are two main types of auctions:
    • Forward capacity auctions: held years before the capacity is needed, giving operators time to upgrade or build facilities. 
    • Incremental auctions: take place closer to the delivery time, adjusting for changes in demand or unexpected generator issues.  

Generally, participants submit sealed bids to offer capacity at specific prices. The auction ends when the total capacity offered matches the region’s needs, and a single clearing price is set for all commitments.  

  • Capacity costs – The charges associated with ensuring a sufficient supply of power to meet peak demand. These charges cover the cost of maintaining and operating power plants, transmission infrastructure, and other components needed to meet the highest levels of electricity usage, essentially guaranteeing power is available when it’s most needed.
  • Capacity market – A type of wholesale market designed to ensure there will be enough power generation available in the future to meet peak demand and maintain grid reliability. Generators receive payments for promising to be available to produce electricity when needed, even if they aren’t running all the time. Functions sort of like an insurance policy, in that generators are paid for the promise to show up with power during times of high demand. This type of market is a method to maintain resource adequacy. Not all markets use this method (example: Electric Reliability Council of Texas (ERCOT).
Clean firm energy

An energy source that generates electricity with zero- or extremely low-carbon emissions, and can do so when needed, regardless of weather conditions. They include enhanced geothermal energy and advanced nuclear technologies. They also can include solar or wind paired with battery storage to provide on-demand power supply regardless of weather conditions or time of day. 

Connect and manage

Refers to a regulatory approach for connecting new power generators to the electrical grid, notably used in Texas (ERCOT). This approach allows new generators to connect expeditiously with minimal upfront transmission upgrades. However, the grid operator retains the right to curtail their output if transmission constraints arise. This contrasts with approaches where developers pay for upgrades prior to connection. (see Energy-only interconnection approaches)

Critical Issue Fast Path (CIFP)

An accelerated stakeholder process used in PJM Interconnection to resolve urgent, contentious, and time-sensitive issues that cannot be resolved through the normal stakeholder process. The process involves several stages of discussion and proposal development, culminating in a submission to the Federal Energy Regulatory Commission (FERC) for approval. The CIFP process has been used in recent years to discuss large load additions (2025) and resource adequacy (2023).

Demand-response programs

These incentivize customers to reduce, increase, or shift their electricity consumption in response to price spikes or grid reliability signals. Most programs encourage utility customers primarily through price incentives to shift electricity consumption from hours of high demand (relative to energy supply) to hours when energy supply is plentiful (relative to demand).

Demand-side solutions

These encompass strategies and programs designed to influence electricity consumption patterns on the customer side of the meter. These initiatives aim to moderate electricity demand through methods such as financial incentives for energy conservation and energy efficiency measures, like improved insulation or the adoption of energy-efficient appliances. 

Dispatchable energy

Refers to electricity generation resources that power grid operators can control and adjust on demand to meet changing electricity needs. These include nuclear, hydropower, battery storage, and thermal power plants.

Distributed Energy Sources (DER)

Small-scale energy generation and storage technologies located near the point where the energy is used, rather than at a centralized power plant. These resources–such as solar microgrids, rooftop solar, and battery storage–can be used to enhance or replace traditional energy sources and can operate independently or be connected to the main grid. 

Disturbance

Refers to any unwanted or unplanned electrical event that interferes with the normal operation of the electrical grid. These can manifest in power outages, surges, and other events, and can originate from various sources within the electrical grid, such as loss of a large generating unit or another grid asset, such as a transmission line or transformer.

Disturbance ride-through

The ability of a piece of electrical equipment to stay connected to the grid through a short-term disturbance, thus helping keep the grid stable through the event. Inverter-based resources, such as photovoltaic solar arrays, wind turbines, and battery storage, can provide disturbance ride-through services, but require specific design of their control system to do so.

Docket

In energy regulation, it is a formal proceeding or official record initiated by a regulatory body (such as a Public Utilities Commission or the Federal Energy Regulatory Commission (FERC)) to address a specific issue or project. It serves as a repository for all submitted documents, evidence, and public comments.

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