POWER GRIDHow Does the U.S. Power Grid Work?

By James McBride and Anshu Siripurapu

Published 5 July 2022

Responsible for powering the country and its economy, the U.S. energy grid has come under increasing strain due to climate change, and the threat of cyberattacks looms. The U.S. electric grid brings power to millions of homes and businesses via a vast network of transmission and distribution lines. Experts say the grid is increasingly vulnerable to extreme weather events, such as the February 2021 Texas winter storms, and cyberattacks. President Biden has proposed overhauling the grid, but his plans could face legal and political hurdles.

A vast network of power plants, transmission lines, and distribution centers together make up the U.S. electric grid. The grid constantly balances the supply and demand for the energy that powers everything from industry to household appliances. Out of sight for most, the grid usually only comes to public attention due to large-scale failures, such as the blackouts that struck Texas in early 2021. 

Extreme weather events influenced by climate change and vulnerability to cyberattacks have raised concerns about the grid’s reliability. Emissions from electricity generation are a substantial driver of climate change, and there is an urgent need to transition away from fossil fuel–based power. But a June 2022 Supreme Court ruling constrained  the ability of the Environmental Protection Agency (EPA) to regulate emissions from power plants, which means the grid could continue to rely on fossil fuels.

Meanwhile, the rise of renewable energy and so-called distributed generation, or the ability of individual homes and businesses to produce their own power, has placed the traditional grid under increasing pressure. It is losing customers at the same time that its aging infrastructure requires a major—and expensive—overhaul. A sweeping infrastructure law passed in late 2021 provides about $65 billion for grid improvements, and the Joe Biden administration has started working with states to accelerate upgrades. 

How Does the Grid Work?
The U.S. electric grid dates back to 1882, the year that Thomas Edison unveiled the country’s first power plant at the Pearl Street Station in lower Manhattan. While the grid has expanded from Edison’s original fifty-nine customers to hundreds of millions of users, for decades its basic structure has remained much the same. According to the U.S. Energy Information Administration (EIA), fossil fuel–based power plants—burning coal, oil, or natural gas—create about 60 percent of the nation’s power, while nuclear power accounts for nearly 20 percent. Electricity is sent across long distances using high-voltage transmission lines, and local facilities known as substations convert that high-voltage power to a lower voltage (a process called “stepping down”) and distribute it to nearby homes and businesses.

Taken together, the grid has been called the largest machine in the world, comprising eleven thousand power plants, three thousand utilities, and more than two million miles of power lines. In practice, however, there are three separate U.S. grids, or self-contained interconnections of power production and transmission. These are the Eastern, Western, and Texas interconnections.