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)

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.

(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). 

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.

California ISO

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).

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. 

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)

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).

Fuel cell that carries energy generated from another source. It can be used in fuel cells to generate electricity with water as the only byproduct, or it can be burned for heat. Hydrogen can be produced from a variety of sources–renewable energy such as solar or wind, or gas plants, nuclear, and other energy sources–which dictate whether it can be considered “clean” or not.

The brief periods when electricity consumption is at its highest, often driven by factors like extreme weather or heat events. This is the highest amount of electricity demand for which a grid operator needs to plan.

A power plant that is designed to quickly ramp up and provide electricity during periods of high energy demand, such as during hot summer afternoons or cold winter evenings, to meet the increased needs of households and businesses. These plants generally only run during these peak events to supplement regular power generation. 

A regulatory tool that ties a portion of utilities’ earnings to the utilities’ performance on desired regulatory outcomes, offering utilities opportunities to create the programs and services needed to advance emerging priorities.

The conversion of light into electricity at the junction of two substances exposed to light. A photovoltaic system employs solar modules, each comprising a number of solar cells, which generate electrical power.

Pennsylvania-New Jersey-Maryland Interconnection- services 13 states in Midatlantic and Midwest region

The rate of transfer of energy. It’s essentially how quickly energy is being used or converted from one form to another in an electrical circuit. Power is measured in watts (W), which represents one joule (J) of energy per second.

A measure of how efficiently electrical power is being used. It shows how much of the total power flowing in a circuit is actually doing useful work (active power) versus being ”wasted” as reactive power. A power factor closer to 1 means higher efficiency and fewer losses.

Sometimes also called a Public Service Commission (PSC), is a state-level governmental agency that regulates utilities like electricity, gas, and water. PUCs ensure that these essential services are provided fairly, reliably, and at reasonable prices, often by overseeing monopolies and protecting consumers.

For electricity infrastructure, like power lines and generating facilities, these requirements involve a range of considerations, including safety, environmental impact, and community engagement. Specific regulations vary by location and project type, but generally include distance requirements from existing infrastructure, environmental assessments, and engagement with landowners and stakeholders.

The conversion of sunlight into electricity using photovoltaics (PV) or solar thermal technologies. It’s a renewable energy source that is becoming increasingly important in the global energy landscape due to its sustainability and decreasing costs.