Why haven't summer's extreme heat waves caused any blackouts? Renewable energy is helping.

Florida is set to experience heat index values of up to 115 degrees this week. Persistent, scorching temperatures covered much of the Southwest, expanding into the Midwest and Northeast in July. Record after record was broken.

And yes so far, the nation's electric grid has held firm. No blackouts, as happened in California in 2022. No brownouts as the Electric Reliability Council of Texas warned could happen this summer. No rolling power outages as the North American Electric Reliability Corporation (NERC) alerted might be an issue in the hottest summer months.

Instead, several things are going right.

Energy experts say four things have come together to make this summer, while hot, nowhere near as dangerous as it might have been had power systems failed leaving thousands without the air conditioning that's now a matter of survival during heat waves.

• More diversification of energy sources, including increasing amounts of wind and solar
• Better planning and preparedness
• Higher levels of hydroelectric power due to heavy winter rain and snow in the West
• Demand response programs offer consumers rebates to ease up on energy use in the hottest parts of the day.

"It's kind of sad that we expect the grid to fail," said Kyri Baker, a professor of engineering at the University of Boulder, Colorado who studies power systems. While the energy grid as a whole is getting creaky, the energy sources are diversifying and making it more flexible.

"We just have more levers to pull in general," she said.

Millions expected to suffer as heat dome expands beyond Texas this week: Graphics

Wind and solar to the rescue

Over the past 70 years, the United States' energy mix has changed substantially, shifting from coal, natural gas and hydroelectric power from dams in 1950 to greater reliance on natural gas and nuclear in 2000. But in the last 20 years, an increasing part of the mix has been made up of ever-cheaper wind and solar power.

Last year, 14% of US electricity was generated by wind and solar. The US Energy Information Administration predicts that will reach 16% this year and 18% in 2024. When hydroelectric power is added in, renewables produce almost one-quarter of all US electric production.

Ten years ago, most utilities relied on several large-scale power plants that supplied power to consumers. Today that's much more likely to be a mix of natural gas, nuclear, wind, solar, hydro and possibly a coal plant or two, plus electricity stored in battery farms.

"Diversity is really your friend," said John Moura, director of Reliability Assessment and Performance Analysis for NERC.

This has been especially important in Texas, said Tyler Hodge, a senior economist with the US Energy Information Administration.

"Texas has been reaching new records pretty much every day in terms of peak hourly electricity use," he said. Last year the state's peak electricity demand was over 80,000 megawatts. "So far this year they've broken that level at least ten times."

But even though the Lone Star state has sweltered under oppressive heat waves this summer, its grid has held because the diversity of the state's power inputs has made it very flexible.

"Demand has gone up a lot from last year, an incredible amount, but we built enough new capacity in the last year to keep up with it," said Michael Webber, a professor of energy resources at the University of Texas at Austin.

On August 10, solar was producing 17% of the state's electricity, wind almost 10% and natural gas 53%, according to the Electric Reliability Council of Texas, the organization that operates Texas's electrical grid. Despite excessive heat warnings in parts of the state, the grid was still operating smoothly and easily able to meet demand.

Having multiple different sources of energy has allowed the Texas grid to keep up with demand. It's not an either/or situation as some critics try to make it, Webber said.

“No one's proposing that you would build a grid out of 100% wind and solar, no one serious anywhere,” he said. Instead, energy experts want to see a grid that’s based on wind, solar, nuclear, hydro, geothermal and batteries “and then you use natural gas for your critical times.”

For now, the solar panels he has on his house in Austin are generating all the power he needs to cover air conditioning during the hottest part of the day, when temperatures this weekend are expected to hit highs of 107 degrees.

"I have ten kilowatts of solar on my roof and my peak demand for air conditioning is four or five kilowatts."

Winter rains make summer electricity

In the Golden State, another bit of wiggle room has come in the form of rain and snow. Last year’s torrential storms in California caused flooding and mayhem but also filled reservoirs and created deep snowpack.

That meant more electricity from hydroelectric dams. On average, hydro provides 15% of California’s electricity generation, but it’s highly variable, from 7% in dry years to over 20% in wet years, according to the Public Policy Institute of California.

"Even though it's a small proportion when you have peak demand and you're running close to capacity, it's good to have that buffer of available hydro," said Hodge.

More looking into the crystal ball

With recent experiences like the Texas blackouts of 2021 that killed 246 people, power systems, always strong planners, have gone into overdrive to look toward what's coming.

"Providers are realizing this is going to be more of an issue," said Baker. "The North American Electric Reliability Corporation  is giving more warning," the said, the gist of which is simple: "Temperatures are going to be high, demand is going to be high – you'd better prepare."

Even though the nation has seen record-breaking peak demands, the system is holding, said John Moura, director of Reliability Assessment and Performance Analysis for NERC.

"Reliability is the outcome of years and years of planning," he said.

Taking control of thermostats

In times of extremely high power demand, taking even a little bit of the load off the system can mean the difference between smooth sailing and what power companies call load shedding but what consumers see as cascading blackouts.

One technique used in industry since the 1970s is what's known as demand response. When power prices or demand spike, energy-intensive industries such as smelting or cement might agree to cut their power use during periods of high demand, in exchange for lower bills.

It's since shifted to less energy-intensive businesses. For example, a supermarket might reduce air conditioning during off-hours or a warehouse might dim its lighting.

With the development of smart meters and thermostats in the past decade or so, utility companies have begun making voluntary demand response programs accessible to consumers as well.

In 2021, just over 10.2 million residential utility customers participated in demand response programs saving 8,700 megawatts of power, said Steve Nadel, executive director of the American Council for an Energy-Efficient Economy.

"That's almost nine large nuclear plants worth of power," he said.

Called voluntary energy shifting programs or demand response, customers grant their utility the right to slightly lower their energy use when power demand spikes, in return for a small credit on their bills. They're a little like an airline offering travel vouchers in return for taking a later flight when the one they're booked on is oversold.

"We didn't have control at the residential level 30 years ago," said Baker. "We could ask the smelters to turn off their furnaces but we couldn't reach into people's houses and turn their thermostats up a few degrees."

During Portland, Oregon's massive 2021 heat wave, a demand response program allowed Portland General Electric to drop demand by 62 megawatts, avoiding rolling blackouts and possibly permanent damage to overheating equipment.

That 62 megawatts is the equivalent of energy for 25,000 homes and the utility says the program works so well it's begun thinking of it as a "virtual power plant."

All four of these trends have kept power flowing and air conditioners running nationwide, but no one's resting easy yet.

"Summer is not over," Moura said. "We're still looking into the next couple of weeks – there are still risky periods to come."

Contact Elizabeth Weise at [email protected].