The potential benefits of shifting the southern two-thirds of the state of Illinois to the power grid employed by northern Illinois doesn't outweigh the massive economic costs.
That's the conclusion of a study Ameren Illinois commissioned at the behest of the Illinois Commerce Commission. The report submitted late last month concluded the state would face an additional $3.4 billion in costs from 2025 through 2034 if a switch was made from the Midcontinent Independent System Operation (MISO) grid to the PJM Interconnection grid.
MISO is employed by parts or all of 15 U.S. states and the Canadian province of Manitoba. The region includes the parts of Illinois serviced by Ameren Illinois, Springfield's City, Water, Light, and Power (CWLP), and the Southern Illinois Power Cooperative in Marion.
The ICC directed Ameren to commission a study of a grid switch last July after concerns were raised about MISO's ability to maintain reliable service, particularly during summer peak demand.
The 84-page study compiled by consultants Charles River Associates concluded that joining the PJM grid would ultimately drive up costs for both Ameren and ComEd customers in the northern region, primarily due to increased capacity costs.
"Joining PJM did result in some benefits, such as reduced emissions and increased resiliency, but these benefits are outweighed by the significant economic costs," the study concluded.
MISO announced in May that there is enough power generation capacity to meet demand for the upcoming year, to favorable market reaction.
Clair Moeller, MISO's president and chief operating officer, said in a May statement that the positive forecast is a sign the grid operator's new seasonal approach to resource planning is a step in the right direction.
“As we navigate an unprecedented transformation of the power system, we must continue to make further enhancements to maintain reliability and send the right pricing signals to the market," Moeller sad.
But MISO has also noted the delayed retirements and imports of more existing capacity that helped the grid meet demand in 2023 may not be an option in the future.
The ICC has opened a notice of inquiry into the Ameren Illinois study. That includes a three-month comment period for stakeholders to weigh in. The commission hasn't yet signaled if it will pursue new rules for the state's power grids.
