A little more than two years ago, a clean energy record was broken. For the first time, a regional transmission organization met more than 90% of its electric demand, called load, with renewable power.

But if you don’t follow the electric industry closely, you might be surprised where it happened.

On March 29, 2022, Southwest Power Pool, based in Little Rock, Arkansas, and the grid operator for a red-state heavy portion of the central U.S., hit a renewable penetration level of 90.2%, almost all of it from wind power.

“In a decade’s time, our region has gone from thinking of 25% renewable-penetration levels as nearly unreachable to a point where we regularly exceed 75% without reliability concerns,” said Bruce Rew, SPP’s vice president of operations, in a news release.

Growing electric demand, major coal plant closures and more wind and solar power have been seen by some policymakers, regulators and clean power critics as harbingers of a coming electric reliability crisis.

During a campaign event last year in Iowa – which got more than 64% of its electricity from wind turbines in 2022 – former President Donald Trump criticized intermittent power and mused about a couple unable to watch TV because the wind wasn’t blowing. The Project 2025 plan organized by the conservative Heritage Foundation for a future GOP administration said? President Joe Biden’s carbon reduction targets, as well as corporate and state clean power goals, “have thrust the United States into a new energy crisis,” including a less reliable grid.

However, in parts of the country that are home to tens of millions of people, grid operators every day are finding that a cleaner electric grid isn’t necessarily a less reliable one, though it does come with new problems to solve.

“The future is already here, it’s just unevenly distributed,” said Ric O’Connell, executive director of GridLab, a nonprofit that provides technical assistance to renewable power advocates and regulators on electric grid issues.

‘Some kind of magic amount’

Nationwide, wind and solar accounted for a little more than 14% of utility-scale electric generation in 2023, according to the federal Energy Information Administration. But in Texas, California and the states that make up SPP, among other areas, the amount of renewable power on the grid at any given time is often much larger.

California has seen wind, solar and hydropower production exceeding 100% of demand in some cases for hours at a time in the area managed by the California Independent System Operator.

The Electric Reliability Council of Texas, which runs most of the Texas electric grid, has also been setting new renewable penetration records.? At 2:13 p.m. on March 29, nearly 76% of the generation on the system was renewable, mostly wind and solar.

‘I think it’s really important to recognize that we get to these points in time on the grid that we get to these extremely high levels of renewables and the lights are not going out,” said Elise Caplan, vice president of regulatory affairs at the American Council on Renewable Energy, a nonprofit representing renewable developers, investors, manufacturers, utilities, corporate power buyers and other firms.

However, it’s important to note that those records being set are snapshots at certain times. As some experts have pointed out, traditional power plants still need to run even when renewables are surging to balance that variability. And, of course, the wind isn’t always blowing and the sun isn’t always shining. For perspective:? Averaged out over the year, wind was about 37% of the Southwest Power Pool’s generation mix in 2023, with natural gas and coal power plants accounting for about 54% and hydropower and nuclear making up the rest.

But the numbers do show that grid operators are successfully integrating renewable power at thresholds that were thought unworkable not so long ago.

Michael Milligan, an independent power consultant who spent more than two decades focusing on wind and solar integration at the National Renewable Energy Laboratory, where he was the lab’s principal researcher before retiring, said utility engineers in years past routinely assumed there were limits on how much intermittent power the grid could handle, usually a “single digit percent.”

“There was kind of a sense that once we get beyond some kind of magic amount it’s going to get too difficult,” he said. “Actual experience is really valuable.”

Fifteen years ago, “nobody thought we’d have the amount of penetration we have today,” said Howard Gugel, vice president of regulatory oversight for the North American Electric Reliability Corporation, which develops and enforces standards for the power system. But the growth in wind, solar and batteries – also known as inverter-based resources because they convert electricity from direct current to alternating current to send the power onto the grid – has posed new reliability concerns.

Inverter-based resources lack the heavy rotating generators at traditional power plants, which are generally synchronized to the grid frequency of 60 Hz, said Greg Brinkman, an engineer in the grid operations planning group at the National Renewable Energy Laboratory. The natural inertia those synchronous generators provide can help them through grid disturbances without incident, whereas inverter-based resources need software and programming to do so.

Gugel said NERC has reviewed several incidents in which grid “perturbations” caused several inverter-based plants, generally solar, to trip off at the same time. “That began to give us some concerns,” he said.

Last year, the Federal Energy Regulatory Commission directed NERC to come up with reliability standards for inverter-based resources, which the organization is currently developing.

“We have a lot of clean energy and renewable energy resources that are being connected to the grid and this new rule is a great step to address what we see as reliability concerns regarding this transition,” FERC Chairman Willie Phillips said in October. “When appropriately programmed, IBRs can provide operational flexibility and the ability of IBRs to perform with precision, speed and control could mitigate disturbances on the bulk power system.”

Transmission as ‘a great enabler’

Rew, the senior vice president at Southwest Power Pool, which has members in 14 states and about 18 million people living in its footprint, said in an interview that production tax credits helped incentivize a surge of wind power development, which also pushed technological advances that increased the operating capabilities of the turbines, including increased “cut-out” speeds, the wind speed at which the turbine needs to shut down to avoid damage.

A major regional transmission planning and expansion process the organization embarked on in the late 2000s helped knit together what had been a collection of systems individually built for numerous individual utilities and positioned the organization to accommodate large amounts of wind generation.

“These regional projects really opened up transmission constraints and allowed us to operate as a single unit a lot better.That provided us the opportunity to really dispatch throughout the system and allowed us to get additional renewables transferring all around the system,” Rew said.

It was a forward-looking approach that is still paying dividends, he added.

“I think in a lot of ways we were visionary in recognizing what transmission could do as a great enabler,” Rew said. “It enables us not only to have greater reliability because we don’t have the transmission constraints and limitations that we did before but also greater economics and just? greater use of all the generation in the footprint.”

Of course, having large amounts of variable power also comes with challenges. SPP has about 33,000 megawatts of “nameplate” wind capacity, meaning the maximum amount those turbines can generate at optimal conditions. Even though Rew said the SPP region has some of the best wind resources in the world, it runs below that maximum output as a result of outages, differing wind speeds and other factors. That means wind and weather forecasting becomes even more critical to managing the grid. A drop in wind speeds, or an icing event, can mean losing thousands of megawatts of generation quickly. That’s a problem because supply and demand on electric grids need to be balanced in real time to avoid issues that can lead to blackouts or other calamities.

“We’re able to look out 10 days and project what the wind’s going to be, project what the load is going to be and be able to prepare our system to be able to operate with those changes,” Rew said. “There’s a lot that goes into making it successful every day.”

SPP’s electric markets also play a crucial role, since traditional power plants like gas and coal need incentives to be available when needed even though they might be running less often or at reduced output.

“That’s what we’re looking at for our market in terms of how we price the services that are necessary to maintain a reliable system and making sure that, one, we have market products that reflect what we’re using for grid operations,” Rew said. “And, two, that we have a pricing mechanism that appropriately compensates them for those services.”

The grid of the future

For the parts of the country that are lagging in renewable power, adding transmission is seen by clean energy advocates as a major piece of the puzzle.

“There is no perfect resource,” said Caplan, the vice president of regulatory affairs at the American Council on Renewable Energy. The most recent high-profile power grid crises were the result of fossil fuel power plants, mostly gas powered, failing to perform in cold weather, either because of inadequate weatherization or fuel shortages. Wind and solar are weather dependent, but the increasing surge in battery power helps smooth out those variances, storing juice when it’s needed. And transmission lines can create a grid bigger than the weather.

“We recognize that those resources are not always available but through this growth of storage and especially through the growth of transmission you can access renewables across a broader geographic area,” Caplan said.

That’s why a lot of eyes will be on a long-awaited rule from FERC expected to come next week that is intended to address thorny debates over regional transmission planning and how costs for new lines are allocated. Rew, the SPP executive, noted that with SPP’s high quality wind resources, developers outside the footprint might have to build twice as many turbines to get the same power output. Does it make sense to do that to meet, for example, a state renewable energy goal? Or is it better to build where the wind is stronger and use long transmission lines to get the power to where it’s needed?

“It doesn’t make sense for our ratepayers to pay for that in SPP, to export wind out for somebody else to get the benefit,” he said “So how do we do that from a national perspective?”

Groups like ACORE want a national planning rule that recognizes that? “an expansion of the nation’s grid is necessary to reliably and affordably accommodate new generation and improve reliability in the face of increasing severe weather events and wildfires.” They want broader accounting of the full benefits of transmission, “a mechanism to determine a cost allocation method when the states are unable to agree”? and other pro-renewable provisions. However, conservatives, including FERC Commissioner Mark Christie, a former Virginia utility regulator, have chafed at what they characterize as an attempt to force others to pay for the policy decisions of states that are pushing renewable power.

“It would be grossly unfair for FERC to force consumers in other states to pay for projects implementing the policies of politicians they never got the chance to vote for, when their own states’ policy-makers have not agreed to pay for those projects,” Christie wrote in response to a letter from four New York congressmen. “Such an imposition is contrary to American principles of democracy, a core principle of which is that the people have the right to elect the policy-makers who impose costs on them, so the people can hold them accountable.”