MISO said it’s expecting a hot summer footprintwide and while it should be able to survive load peaks into the 120-GW level, the system could be at the brink if a scorching day produces demand near 130 GW.  

Per usual, MISO said the bulk of the danger lies in July. MISO said it likely will encounter a 122.6-GW peak sometime that month but doesn’t rule out a high-demand forecast of 129.3 GW. That level of demand would break all load records, outstrip its 123.8 GW of cleared, accredited capacity and force it to declare an emergency to access its approximately 15-GW store of operating reserves and load-modifying resources.  

In June, MISO said load could crest at an expected 115 GW or climb near 122 GW in a high-demand scenario. By August, MISO expects an almost-120-GW peak load under normal conditions, or as much as 126 GW.  

MISO’s all-time summer peak of 127 GW occurred July 20, 2011. Last year, MISO expected to eclipse that record twice during late August and early September heat waves that produced temperatures exceeding 95 degrees in northern portions of the footprint. MISO rounded out summer with a 125-GW peak Aug. 23. (See MISO: Could Have Employed Wait-and-see Approach for August Emergency.)  

During a May 21 summer readiness workshop with stakeholders, MISO resource adequacy engineer John DiBasilio said while MISO should have sufficient capacity under normal operating conditions, it’s likely to enact emergency procedures if demand intensifies this summer.  

The RTO estimates it has a 4.6-GW capacity surplus beyond its 136-GW planning reserve margin requirement heading into summer from excess capacity offered into the auction and from members’ fixed resource adequacy plans.  

MISO’s primary weather forecast vendor, data analytics and technology company, DTN, has predicted “above-normal to well-above-normal” average temperatures May through September.  

The RTO noted that the National Oceanic and Atmospheric Administration is projecting above-normal temperatures across the country June through August. MISO also said it expects precipitation this summer between near normal and slightly above normal.  

MISO in-house meteorologists Brett Edwards and Adam Simkowski said it doesn’t seem that the RTO can use last summer, which held nearly normal average temperatures in MISO Midwest, as a reference for the upcoming summer. They said more appropriate reference points include summers where load topped 120 GW systemwide and more than 30 GW in MISO South.

Edwards said all data points to a very warm summer, and MISO expects “pervasive heat across pretty much the entire continental U.S.”  

The RTO anticipates a developing La Niña weather pattern contributing to hotter conditions in July and August.  

MISO also said there’s a good chance heat could emanate from the eastern U.S. this summer, affecting PJM’s ability to export to MISO during heat waves.  

“That’s something we’re going to be watching closely as the entire Eastern Interconnect heats up,” Simkowski said. 

“Our teams are constantly working to identify and manage the areas of growing risk within our region and throughout our industry,” Executive Director of Market Operations JT Smith said in a press release.  

Finally, MISO said while it’s expecting solar penetration to increase to 6 GW of in-service capacity this summer, it’s also keeping an eye on the potential for wildfire smoke drifting from Canada to stifle a percentage of output. MISO has been routinely breaking its own solar records monthly as developers complete solar farms. Currently, MISO’s solar arrays are briefly capable of about 5-GW peaks.