The projected work includes more than $1.4 billion in new transmission infrastructure, $189 million in upgrades to existing transmission equipment and more than $1.5 billion for improvements to the distribution system. The projects involve users that have opened since 2021 or could come online by 2031, each requiring at least 50 megawatts of power — roughly enough for a small city.

The companies involved were redacted in the regulatory filings. The Citizens Utility Board believes the projects are data centers, whose rapid growth is being driven in part by demand for artificial intelligence computing.

Consumer advocates say the gap between projected costs and money committed by the large users leaves households and small businesses exposed if projects are canceled after ComEd has begun construction. “Everyday electric customers are potentially on the hook for billions in higher bills,” said Sarah Moskowitz, executive director of the Citizens Utility Board, which represents residential and small-business utility customers.

ComEd disputes that assessment. A company spokesperson called the consumer groups’ analysis incomplete and said it presents an inaccurate picture. The utility says Transmission Security Agreements approved by state and federal regulators require large-load customers to cover transmission costs for the agreements’ duration, even if they close or use substantially less power than expected.

The utility said it is still calculating the cost of distribution upgrades and the deposits required from large users. Some projects are years from completion, and engineering work needed to estimate those payments is unfinished, ComEd said, adding that the deposit total may rise. The company also said it supports assigning costs to the large-load customers that cause them.

The advocates, including the Environmental Law & Policy Center, the Natural Resources Defense Council, Vote Solar and the Union of Concerned Scientists, argue the agreements do not eliminate the risk that infrastructure could be left unused. They say state leaders should plan for projects that do not proceed, while noting that additional data centers may follow the 30 large users in ComEd’s queue.

The groups are backing the proposed Protecting Our Water, Energy and Ratepayers Act, or POWER Act. It would require data centers to pay all of their grid-related costs before connecting and would establish protections related to pollution and water use.

ComEd has also asked the Illinois Commerce Commission for permission to limit data-center service when the grid is under stress, including during very hot weather. The debate comes as consumers contend with rising household costs: the Citizens Utility Board says ComEd’s electricity supply price is about 50% higher than it was two years ago.

Gov. JB Pritzker has expressed support for data-center regulation. The issue could be considered during the Illinois General Assembly’s veto session in mid-November and early December.