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More Than Flipping a Switch: The Forces Behind America’s Energy Supply

An interconnected network and wholesale energy markets determine which energy sources power our lives.

You probably never think about what goes into making sure the lights go on each time you flip a switch. And that’s OK – because we do.

Energy produced at the nation’s 7,300 power plants travels across 160,000 miles of high-voltage power lines to local utilities. From there, utilities distribute the electricity via low-voltage power wires to our cities and homes. 

This complex, interconnected system is known as the electric grid. In America, there are three main grid networks: one for the eastern, central and western parts of the country. 


Local entities known as Regional Transmission Organizations, or RTOs, manage the flow of energy through the grid. At Exelon, the RTOs for our 14 nuclear power plants are PJM, MISO and the NY ISO. They’re essentially traffic controllers for our region’s high-voltage power lines. Their computer systems gauge energy supply and customer demand at any given moment, in order to direct plants to either scale production up or down in order to maintain balance.

Yet, not all energy sources are treated equally by this system. 

Each year, RTOs hold what are known as capacity auctions. Capacity is a commitment to deliver energy resources when supply is needed on the grid, while leaving enough margins to handle heavy demand, such as during extreme weather. The auctions are structured in a way that favors the lowest-cost energy sources, such as coal and natural gas, over nuclear energy, which produces energy without air pollution and is also extremely reliable. The market’s failure to recognize the benefits of nuclear energy means that many such plants could be forced to retire, putting at risk America’s largest and most reliable source of zero-carbon energy. 

We know from past experience that when nuclear plants retire, air pollution increases as fossil fuel-burning plants take their place. Federal policymakers and authorities such as PJM and MISO must fix the way wholesale energy market prices are established today in order to grow America’s clean, reliable energy supply tomorrow.

Clean energy isn’t automatic. It takes a willingness to embrace change and adapt our current energy systems — for the better. Like we said earlier, there’s a lot happening behind the scenes to keep America’s lights on, and our air clean.