The August 10, 2020 derecho knocked out power to 1.4 million customers in the Midwest. Iowa alone saw 585,000 outages at its peak. More than 50,000 customers remained in the dark more than a week after the storm.

Powerful natural disasters on planet Earth can dismantle the power grid, but there’s another threat out there that could impact the entire globe.

Associate Professor of Physics and Astronomy Gregory Howes at the University of Iowa studies the sun and solar flares – strong storms on the surface of the our solar system's star that can have a big impact here on Earth.

"If you change the magnetic field of the surface of the Earth, you can induce voltages in our electric power grid and that can actually burn out the massive transformers that are about the size of a standard house," Howes said. "It can burn those out and those you know can take weeks to be repaired or perhaps replaced if they're damaged severely enough."

PROTECTING THE POWER GRID

Power providers, like Alliant Energy, are well aware of the threat solar flares can pose to our Earth-based infrastructure. Alliant often takes part in exercises and drills, simulating a threat to the grid like solar flares.

These exercises allow energy providers to prepare for a potential solar storm.

"(Forecasters) provide forecasted and current space weather information," said Morgan Hawk, a spokesman for Alliant. "This is then provided to our generating stations to monitor for anything unusual. Unusual voltages, reactive power, abnormal temps, noise in transformers. So we’ll relay that information and go through the procedures the prepare as much as possible."

The grid does have automated ways of protecting itself in the event of solar flares. Plus, forecasters are actively monitoring the sun for potential threats. There are other, more extreme ways, to protect the grid if a particularly powerful storm is forecast, but that does have consequences.

"Everything in the US, our whole economic engine depends on the power being turned on," Howes said. "There is an economic cost to shutting down the power grid out of caution. We don’t yet have the accuracy of forecast to know when that will be. We don’t want to cry wolf too many times because there is an impact."

On March 13, 1989 a powerful solar storm impacted Earth. In just two minutes, the electric voltage added to the electrical grid caused by a solar flare led to the entire power grid in Quebec, Canada failing. The grid was tripped in the northeast US as well. While the US was able to get back online relatively quick, millions of people in Canada remained in the dark for more than 12 hours.

"It was sort of a proof of principal that it does happen," Howes said. "It can have an impact on the power grid."

To help prevent something like this from happening again, the nation’s Space Weather Prediction Center in Boulder, Colorado now has a direct line of communication with utility companies to alert them when a storm threatens. This is new as of just 2015.

Reliability coordinators, or RCs, are positioned across the US and Canada, on call 24/7.

"We pick up the phone, and that sets off the hard lines to all the RCs," said Bill Murtagh, program coordinator for the Space Weather Prediction Center. "We do a quick roll call. This all happens within a minute. Then we transfer the appropriate information to the 20 or so RCs. They take the information. Any questions? No. Good. Go."

The hope is that this new communication can limit the potential impact from these massive solar storms. While the 1989 storm was strong, it's far from the wort we've ever seen. The fact is we haven’t truly been tested, not since society has become so dependent on electricity.

"There’s a very low recurrence rate," Howes said. "We don’t know when the next one will happen but it can happen."

THE NEXT SOLAR CYCLE

Much like a hurricane season on Earth, the sun has its own period of activity known as a solar cycle.

These 11-year cycles vary from each other, some being more extreme with others being quieter. The sun is starting to wake up now, heading to the next solar maximum, or period of highest activity on our closest star’s surface.

“The solar minimum happened in December 2019,” Howes said. “Now we are heading towards solar maximum. Solar maximum should hit us around the summer of 2025. We’re just going into the period of time when we should see a lot more activity from the sun.”

Activity on the sun comes in the form of solar flares from sunspots. Sunspots are disturbances on the sun’s surface that can emit solar flares. These flares are caused by interactions with the sun’s magnetic field, but this interaction is not well understood.

Also like hurricane seasons, forecasters attempt to predict how active a particular season may be using the available data. Predicting space weather events though can be much more challenging than storms on Earth which have been studied for centuries.

“Our ability to predict a solar cycle is quite limited,” Murtagh said. “We put a group together to make the official prediction a year or so ago, and they concluded less than average.”

Howes at the University of Iowa agrees with a less-than-average season, however he adds the individual season can be defined by just one event, like the way-below-average 1992 hurricane season that included Category 5 Hurricane Andrew hitting Florida.

“Even during a mild solar cycle, one can have a large event, very severe solar flares,” Howes said.

On the other end of the spectrum, scientists from the National Center for Atmospheric Research have predicted the new solar cycle could be one of the strongest on record.

Either way, a below normal season can also have its own concern. While the amount of sunspots and solar flares may be less, the strength of those solar flares can in fact be stronger. To continue the hurricane comparison, multiple hurricanes feeding off the same warm ocean water will help churn the water up and making it cooler, thus removing some available energy. Fewer solar flares may be stronger.

“We see buildup of stress in these regions, it can result in bigger eruptions,” Murtagh said. “The Halloween Storms (of 2003) are a good example. On the 28th of October, we had one big eruption.”

The powerful 2003 Halloween solar storms were some of the most powerful ever measured, and it happened not during a solar maximum but instead a few years after the peak.