Electricity Is Delivered to Consumers Through a Complex Network
Electric power is generated at power plants and then moved to substations by transmission lines — large, high-voltage power lines. In the United States, the network of nearly 160,000 miles of high voltage transmission lines is known as the "grid."
A local distribution system of smaller, lower-voltage distribution lines moves power from substations and transformers to customers.
Electric power generation, transmission, and distribution diagram
Source: National Energy Education Development Project (Public Domain)
from: www.eia.gov/bookshelf/brochures/rep/index.html
Electricity Comes from Various Sources and Kinds of Providers
Did You Know?
Some residential, industrial, commercial, and institutional users of electricity have the means to produce electricity for themselves and sell any excess back to their utility.
The utility, distribution company, or retail service provider selling you power may be a not-for-profit municipal entity, an electric co-operative owned by its members, a private, for-profit company owned by stockholders (often called an investor-owned utility), or a power marketer. Some Federally-owned authorities — including the Bonneville Power Administration and the Tennessee Valley Authority, among others — also buy, sell, and distribute power.
The origin of the electricity you consume may vary. Utilities may generate all the electricity they sell using just the power plants they own. Utilities may also purchase some of their supply on the wholesale market from other utilities, power marketers, independent power producers, or from a market based on membership in a regional transmission reliability organization.
How the Grid Is Organized
Most of the existing grid was built during a highly structured, highly regulated era designed to ensure that everyone in the United States had reasonable access to electricity service. Utility customers, through fees authorized and regulated by State regulatory commissions, generally paid for developing and maintaining the grid.
Source: Energy Information Adminsitration. Map shows NERC (North American Electric Reliability Corporation) regions.
Many local grids are interconnected for reliability and commercial purposes, forming larger, more dependable networks to maximize coordination and planning. These networks extend throughout many States.
The North American Electric Reliability Corporation (NERC) was established to ensure that the grid in the United States was reliable, adequate, and secure. Some NERC members have formed regional organizations with similar missions.
These organizations are referred to as Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs). They are part of a national standard design advocated by the Federal Energy Regulatory Commission (FERC). Some have members who connect to lines in Canada or Mexico. Most, depending on the location and the utility, are indirectly connected to dozens and often hundreds of power plants. Some power consumed in the United States is imported from Canada and Mexico.