An organization that manages transmission systems across the central US announced on Tuesday that it broke a record for wind penetration in North America. On Sunday at 4:30am, Southwest Power Pool (SPP) became the first regional transmission organization (RTO) to serve 52.1 percent of its load using wind energy.

SPP also set the previous record in April 2016 with 49.2 percent wind generation. A record previous to that was set by the Electric Reliability Council of Texas (ERCOT) in late March 2016, when the organization hit 48.28 percent wind penetration at 1:10am.

Windy weather

Why does it seem like all the wind penetration records are broken in late winter to early spring? Derek Winfield, SPP’s corporate communications representative, wrote to Ars to explain: “At least in our footprint, that’s a time of year that’s typically both mild and windy. That means lower total load on our system (due to less power being used to heat/cool homes and businesses, at least in part) and more of that load able to be served by wind.”

Records for wind penetration, which measure the amount of total load supplied by wind on a moment-to-moment basis, are being broken more frequently these days, on a regional and internal level. As RTOs, which generally serve large areas and cross state lines, add more wind turbines to their portfolios, wind is becoming a more important part of the energy mix. SPP noted that “wind is now the third most-prevalent fuel source in the SPP region,” which covers 550,000 square miles of territory in Nebraska, Kansas, Oklahoma, and portions of neighboring states. Natural gas and coal are still the primary fuel sources for SPP, but the organization said that wind accounted for 15 percent of its generating capacity in 2016.

“SPP’s maximum simultaneous wind generation peak rose from 9,948 MW in 2015 to 12,336 MW in early 2016,” the organization added.

In a statement included in SPP’s press release, Vice President of Operations Bruce Rew gave the new numbers some context. “Ten years ago, we thought hitting even a 25 percent wind-penetration level would be extremely challenging, and any more than that would pose serious threats to reliability… Now we have the ability to reliably manage greater than 50 percent wind penetration. It’s not even our ceiling. We continue to study even higher levels of renewable, variable generation as part of our plans to maintain a reliable and economic grid of the future.”

In early 2016, SPP officials told regulators that based on a 2015 study, the transmission system it manages could “‘reliably handle’ wind representing up to 60% of internal SPP load,” although the organization cautioned that it would need to install “voltage reactive support capabilities for existing wind farms” as well as “enhanced operations tools, to monitor real-time voltage stability limits,” among other recommendations.

In its press release today, SPP credited its ability to handle so much wind penetration to the size of the organization’s footprint. “Even if the wind stops blowing in the upper Great Plains, we can deploy resources waiting in the Midwest and Southwest to make up any sudden deficits,” Rew said. That versatility is also helped by a recent and massive investment; in 2012, SPP approved a 10-year, $1.7 billion transmission expansion plan to help meet renewables goals.