It's not just Tennessee: Why blackouts hit large parts of America

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Why is America getting hit with blackouts this winter?

The United States electricity system largely runs on natural gas, and that system was put under severe stress across the country as extreme cold and storms affected the nation’s grid this week.

Cold weather stresses many power systems as the demand for heating homes and other indoor spaces — whether gas or electric — surges.

Much of the country is dependent on natural gas

In much of the country, home heating is provided by natural gas or electricity, putting massive stress on the whole system when nearly the entire country needs lots of heat, as it did in the past week. Gas is either mainly directed towards homes, meaning the electrical system has to find other fuel, or, where homes use electricity directly for heat, there’s a massive increase in demand for electricity.

The Tennessee Valley Authority hit its all-time peak in power generation but was forced to institute rolling blackouts as its neighboring electricity systems were overwhelmed by massive demand earlier this week. The main grid operator in the eastern United States, PJM Interconnection, massively underestimated electricity demand during the cold snap and asked households to conserve electricity. In North Carolina, the utility Duke Energy instituted rolling blackouts. While Texas was able to keep the lights on despite the cold weather (unlike the massive blackout in 2021), the state’s grid operator still underestimated the demand for power.

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In New England, which has meager natural gas infrastructure and relies on imported liquefied gas to get through the winter, gas consumption soared in the last week alongside the use of oil. While oil plays only a minor role in electricity generation in the United States, power plants in New England will use oil when demand gets especially high. This is because natural gas supplies cannot both heat homes and keep the lights on when demand for both power and heat is high.

During the cold snap before and on Christmas, the use of natural gas for heat in New England grew dramatically while electricity generation for natural gas fell off starting the night of Dec. 22, with oil surpassing natural gas in electricity generation the night of Dec. 23.

At certain points in the last week, oil provided as much as 40 percent of the electricity in the region. But, as energy analyst Meredith Angwin told Grid, this wasn’t because of large-scale disruption to natural gas supplies or even necessarily extreme cold.

Instead, thanks to how the system seeks the cheapest form of available fuel for electricity, it can sometimes be cheaper for power plants to run on oil than on natural gas, especially in the winter when high demand for heating drives up natural gas prices. Natural gas is more expensive in New England than in the rest of the country, and the price of natural gas earlier in the week was almost six times more than it was last year, according to Energy Information Administration.

“Even if you get 30 or 40 percent from oil, only 20 percent from nuclear, almost no coal, less than 10 percent renewables usually, you’re still getting a lot of natural gas.” And while overall natural gas use in New England was high this week, according to Energy Information Administration data, natural gas consumption in New England was just under twice the average of the past four years. However, prices were almost six times what they were last December. In other words, both gas prices and usage are up from last year.

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Coal is a backup option — but even coal plants are disappearing

Oil wasn’t the only backup fuel localities used as temperatures dropped.

In the 13-state territory for the grid operator PJM, where coal is responsible for about one-fifth of the electricity on an annual basis, coal use shot up to 28 percent of generation on Wednesday and was often responsible for around a quarter of generation throughout the week.

On the morning of Dec. 21, natural gas was generating about 48,000 megawatt hours of electricity, while coal was responsible for 28,000 megawatt hours. At the same time on Christmas Eve, gas was generating 37,000 megawatts of electricity, while coal was generating 32,000 megawatts, along with about 6,000 megawatts from wind that wasn’t available three days prior.

Coal plants throughout the country are rapidly being retired. Coal generation has almost been cut in half in the past decade, while natural gas electricity generation has increased by more than 50 percent. And coal power is not perfectly reliable in inclement weather either. The TVA told the Chattanooga Free Press that winds damaged one of its coal plants and several gas facilities.

Some have pointed to generation and transmission struggles as evidence of the brittleness of America’s natural gas infrastructure, which is responsible for more electricity generation than any other single source (38.4 percent). For the industry, the past week has shown just how much the U.S. depends on natural gas.

“During last week’s brutal cold, the U.S. natural gas market likely set a *record* for daily delivered volumes, including a new winter high for gas flows to power generation,” Richard Meyer, a vice president at the American Gas Association, tweeted. “There were some local operational challenges, yes. But flimsy the gas system is not.”

The American electric grid will likely be dealing with two challenges going forward — extreme weather and extreme transformation. With continued coal retirements and the weight of federal policy now firmly behind non-carbon sources of electricity, the grid will continue to shift, both in finding ways to generate the power we use today while emitting fewer greenhouse gases and powering more as the largest source of emissions, transportation, becomes increasingly electrified. The challenge now is whether the policy being proposed to deal with climate change can work fast enough to deal with its consequences.

Thanks to Brett Zach for copy editing this article.

  • Matthew Zeitlin
    Matthew Zeitlin

    Domestic Economics Reporter

    Matthew Zeitlin is an economics reporter at Grid focused on the domestic impact of major stories such as coronavirus, the supply chain and economic volatility.