US utility ComEd jolts Illinois wind and solar ambitions with major substation upgrade

Commonwealth Edison will expand a 765kV substation in Illinois to support 2.45GW of new solar and onshore wind, roughly 30% of the state’s present installed capacity and the type of investment by utilities that President Joe Biden wants to accelerate the US energy transition and achieve a carbon-free grid by 2035.

Upgrading makes good use of the existing electrical infrastructure footprint, facilitates regulatory approvals, and can sometimes result in addition of significant renewable energy generating capacity within a state faster than new transmission lines.

The $55m investment will expand the Wilton Center substation yard in northern Illinois by 50% to enable interconnection by late 2026 of five wind farms totaling 2GW of capacity and two solar arrays comprising 450MW.

The wind farms include up to 850MW Heritage Prairie being developed by ConnectGen and Pattern Energy, more than double capacity of the state’s largest in operation. The project includes 300MW of solar.

Heritage Prairie will also be the largest onshore wind project in the PJM Interconnection, which operates the nation’s largest regional grid serving all or parts of 13 mid-Atlantic and midwestern states and District of Colombia. PJM has lagged other regional grids with utility-scale solar and wind development.

Other wind projects to be connected by ComEd are Tri Global Energy’s twin 400MW Panther Grove I and II; Cordelio Power’s 200MW Lower Crossing, and Avangrid’s 150MW Osagrove Flats, which will include 150MW of solar.

“Policymakers, stakeholders and customers want a cleaner energy future, and we’re powering the grid modernization that will make this future a reality,” said ComEd CEO Gil Quiniones.

“Investments like the expansion of the Wilton Center substation will ensure the successful interconnection of new renewable energy generation to the grid so that it can be delivered through our transmission system to communities across Illinois,” he added.

Substation design engineering began in September, and work will include installation of new circuit breakers, transformers, relay switches, network data and control systems.

Governor JB Pritzker called the solar and wind farms supported by the substation expansion “another step in Illinois’ clean energy journey.”

Illinois on 1 January had 7.12GW of installed wind capacity and 974MW of grid-scale solar, according to American Clean Energy Association, a national trade group.

The state has a renewable portfolio standard that requires investor-owned utilities to obtain 50% of their electricity sales from renewable energy sources by 2040 and 100% by mid-century.