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IL — Power Infrastructure Updated 2026-07-17

Illinois

MISO/PJM Solar Wind Storage Data Center PPAs Queue Bottlenecks Transmission Constraints

1) Grid operator and market structure

  • RTO/ISO coverage: Illinois load is served by both PJM and MISO; the Illinois Resource Adequacy Study evaluates Illinois in the PJM ComEd zone and MISO LRZ 4 and notes that Illinois is a restructured state whose RTOs operate wholesale energy/capacity markets. Illinois 2025 Resource Adequacy Study, 2025-12-15
  • Retail market structure: Illinois has retail choice for ComEd and Ameren Illinois customers, which allows large customers to procure competitive supply even though distribution service remains utility-provided. Illinois Commerce Commission, accessed 2026-07-17

2) Interconnection queue (status, wait times, reforms)

  • MISO queue depth and mix: MISO’s 2023 generator interconnection queue cycle included 600 applications / ~123 GW and would bring MISO’s queue to ~348 GW if validated, with solar, storage, wind, and hybrid projects dominating. MISO, 2024-04-23
  • PJM queue reform: PJM’s FERC-approved interconnection reforms shifted the queue from first-come/first-served serial studies to a first-ready/first-served cycle approach, effective January 3, 2023. PJM, accessed 2026-06-10
  • Data-center-specific load requests: The Illinois RA Study reports that MISO is seeing significant data-center interconnection requests and expects about 500% growth in data-center loads from 2025 to 2030, while ComEd data-center additions are not fully reflected in PJM’s then-current forecast. Illinois 2025 Resource Adequacy Study, 2025-12-15
  • Large-load service threshold in ComEd proceedings: The ICC’s March 2026 large-load investigation describes Large Demand Project Applicants or Customers as requests of 50 MW or more, which is the practical threshold at issue for many data-center grid-connection disputes in ComEd territory. Illinois Commerce Commission, 2026-03-20
  • Average wait-time context: LBNL reports typical U.S. generator request-to-commercial-operation timelines of more than four years for projects built from 2018-2023, with a median of about five years in 2023. Lawrence Berkeley National Laboratory, accessed 2026-06-10
  • Federal reform backdrop: FERC Order No. 2023 requires cluster studies, stronger readiness and site-control requirements, and greater process transparency to address queue backlogs. FERC, accessed 2026-06-10
  • June 2026 federal large-load proceedings now cover both Illinois RTOs: On June 18, FERC opened Section 206 show-cause proceedings for every RTO/ISO, including PJM Docket EL26-67-000 and MISO Docket EL26-70-000. Within 60 days, each RTO must justify or revise its rules for large-load applications and studies, cost-shift protections and transparency, co-location/behind-the-meter generation, flexible-load transmission service, and expedited study of proximate generation; each also owes a 30-day resource-adequacy report. These are pending proceedings, not final Illinois interconnection rules. FERC, 2026-06-18 FERC, 2026-06-18
  • MISO large-load process development: MISO is developing a three-part large-load framework and, in June, sought stakeholder feedback on a proposed Firm Service Step-Up approach that could give qualifying large loads reduced firm service before all network infrastructure is complete. The proposal remained under development as of July 17 and is not yet an approved Illinois service right. MISO, 2026-06-10 MISO, accessed 2026-07-17

3) Ratepayer protection (large-load tariffs / cost-allocation rules)

  • Existing ComEd large-load delivery classes: ComEd’s ICC tariff book includes Large Load, Very Large Load, and Extra Large Load delivery classes with distinct customer and demand charges. Illinois Commerce Commission tariff book, accessed 2026-06-10
  • ComEd deposit and tariff changes approved in March 2026: The ICC allowed ComEd to increase security deposits for large-load projects such as data centers and characterized the move as an initial consumer-protection step, while directing further proceedings on unresolved large-load issues. Capitol News Illinois, 2026-03-20
  • ICC investigation is active in Docket 26-0364: The ICC opened the promised proceeding on April 23, 2026 to investigate ratepayer protections and cost recovery for ComEd large-demand projects. The schedule calls for Staff/intervenor direct testimony on June 26, ComEd direct testimony on July 31, an evidentiary hearing beginning September 14, and a proposed order around November 9; consumer, environmental, industrial-customer, community-opposition, generator, and data-center-industry parties have intervened. As of July 17, the Commission had not decided whether to create a separate data-center tariff or how to allocate all large-load costs. Illinois Commerce Commission Docket 26-0364, initiated 2026-04-23 and updated 2026-07-09 Illinois Commerce Commission, 2026-05-11
  • ComEd pipeline scale in the ICC record: The ICC press release states that ComEd had 75 customer applications in its pipeline with combined maximum demand surpassing ComEd’s all-time system peak, and ICC docket materials in the same proceeding describe more than 75 unique large-demand projects totaling more than 28,000 MW of maximum demand. Illinois Commerce Commission, 2026-03-20 Illinois Commerce Commission Docket 25-0679, 2025-11-04

4) Generation adequacy (major projects and resource additions)

  • Adequacy risk driven by data centers: The Illinois RA Study finds that data centers are the primary driver of load growth and that PJM and MISO face projected capacity shortfalls absent additional new resources; it reports resource-adequacy targets rising about 20% in PJM and 10% in MISO from 2025-2030, largely due to data-center growth. Illinois 2025 Resource Adequacy Study, 2025-12-15
  • MISO resource additions: MISO’s 2023 interconnection queue cycle is dominated by solar, storage, wind, and hybrid resources, meaning much of the planned resource mix serving Illinois’ MISO zone is renewable and storage-heavy. MISO, 2024-04-23
  • Expedited Resource Addition Study (ERAS): FERC approved MISO’s ERAS process to fast-track a limited number of generation projects tied to specific load additions or resource-adequacy deficiencies, capped at 150% of need and limited to the same Local Resource Zone. MISO, 2025-03-03

5) Utility load forecasts (data-center driven load growth)

  • PJM forecast adjustments for ComEd: PJM’s 2025 Long-Term Load Forecast explicitly adjusts the COMED zone forecast for data-center load growth and an EV battery plant, making data centers a modeled load-growth driver for Illinois’ PJM zone. PJM, 2025-01
  • ComEd 2028-2031 grid plan: ComEd’s January 2026 grid-plan filing in ICC Docket 26-0047 states that data-center load accounts for more than 47% of new load growth and that large-load forecasting relies on customer capacity requests, ramp schedules, in-service dates, and cross-checks against historical demand. Illinois Commerce Commission Docket 26-0047, 2026-01-16
  • ComEd infrastructure plan cost: ComEd filed a $15.3 billion 2028-2031 grid plan for ICC review, which Capitol News Illinois reported would add an estimated $2.50-$3.00 to the average residential customer’s monthly bill if approved in full. Capitol News Illinois, 2026-01-23
  • Grid-plan case remains pending: Docket 26-0047 continued through testimony and discovery after the January filing; no final ICC approval or cost allocation had occurred by July 17, so the $15.3 billion figure remains ComEd’s proposal rather than an authorized investment plan. Illinois Commerce Commission Docket 26-0047, updated 2026-07-16
  • House hearing load-growth evidence: During April 2026 House Executive Committee hearings, ComEd’s pipeline was described as approaching 33,000 MW, more than the utility’s historical peak load, with data centers potentially accounting for 70% or more of new load growth. Illinois State Association of Counties, 2026-04-16
  • Local energy disclosure standard in McLean County: The county’s June 11 zoning amendment requires a data-center applicant to disclose required electricity, peak load, supply sources and onsite generation, describe grid-impact and clean-energy measures, and notify the county if energy needs rise by more than 20%. This is a local siting/reporting rule, not an ICC tariff or statewide utility-forecast requirement. McLean County Board, 2026-06-11
  • MISO long-term forecast drivers: MISO’s December 2024 long-term forecast identifies data centers as a primary load-growth driver, with MISO peak demand expected to rise about 1%-2% CAGR through 2044 and data centers driving much of the northern-footprint growth. MISO, 2024-12

6) Behind-the-meter / co-location / direct procurement

  • Direct procurement enabled by retail choice: Illinois retail choice lets large ComEd and Ameren customers procure competitive supply, which supports direct procurement and PPA structures even when distribution interconnection and delivery are utility-regulated. Illinois Commerce Commission, accessed 2026-07-17
  • PJM large-load integration process: PJM’s Critical Issue Fast Path for Large Load Additions is focused on integrating large new loads and coordinating data-center relationships with LSEs and EDCs. PJM, accessed 2026-06-10
  • MISO ERAS ties resources to load: MISO ERAS requires state regulator verification that a project addresses a specific load addition or resource-adequacy deficiency, providing a path for load-linked generation additions. MISO, 2025-03-03
  • Co-location rules remain unsettled: FERC’s June order also required PJM to make a further compliance filing in its co-location proceeding, EL25-49-002, while the broader PJM and MISO show-cause cases examine behind-the-meter generation and new flexible transmission service. These federal cases may shape Illinois data-center configurations but had produced no final state-specific rule by July 17. FERC, 2026-06-18
  • Policy proposals, not enacted mandates: The POWER Act would have required data centers to pay for their own renewable energy generation and to report water use, but it did not pass during the spring session; Gov. Pritzker’s June incentive pause also stated a policy preference that utility-scale data centers generate or support new power, but the pause itself did not enact a behind-the-meter mandate. Capitol News Illinois, 2026-05-30 Governor JB Pritzker, 2026-06-05

7) Transmission constraints and planned upgrades

  • Illinois zonal import constraints: The Illinois RA Study notes that PJM and MISO use zonal transfer limits, including PJM CETL and MISO ZIA, to determine whether zones such as ComEd and MISO LRZ 4 can import enough capacity, which can constrain data-center siting in transmission-limited areas. Illinois 2025 Resource Adequacy Study, 2025-12-15
  • ComEd substation/transmission coordination: ComEd’s 2028-2031 grid plan links load growth from large customers, including data centers, to substation projects in areas such as New Elk Grove, Mannheim, Van Buren, and Lakeview, and states that distribution forecasts are provided to ComEd transmission planning for PJM load-flow modeling. Illinois Commerce Commission Docket 26-0047, 2026-01-16 Illinois Commerce Commission Docket 26-0047, 2026-01-16
  • MISO-SPP seam upgrades: MISO’s Joint Targeted Interconnection Queue portfolio addresses seam transmission constraints and is expected to enable about 28.6 GW of new generation with about $1.6 billion of upgrades approved in MTEP24. MISO, accessed 2026-06-10

Gaps / items to verify (public data limits)

  • Illinois-specific load interconnection queue: Illinois does not publish a statewide public load interconnection queue; large-load requests are handled through utility, PJM, and MISO processes, and public details on data-center-specific projects remain limited beyond ICC proceedings, RTO documents, and local project approvals. Illinois Commerce Commission, 2026-03-20
  • Project-level generation list: The RA Study and RTO queue materials provide resource-type and volume signals, but they do not list every plant-level Illinois generation addition tied to data-center load; plant-by-plant tracking still requires filtering PJM and MISO queue datasets by location and interconnection status. Illinois 2025 Resource Adequacy Study, 2025-12-15
  • No final large-load class or statewide cost-allocation rule yet: The March deposit change is effective, but the comprehensive ComEd large-load tariff issues remain pending in ICC Docket 26-0364, while PJM and MISO rules are also under federal review. Illinois Commerce Commission Docket 26-0364, updated 2026-07-09 FERC, 2026-06-18