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WI — Power Infrastructure Updated 2026-07-17

Wisconsin

MISO Natural Gas Nuclear Solar Storage Coal Data Center PPAs Queue Bottlenecks Transmission Constraints

Last updated: 2026-07-17.

1) Grid operator and market structure

  • RTO/ISO / balancing authority: Wisconsin is in the Midcontinent Independent System Operator (MISO) footprint, and FERC describes MISO as operating the grid in portions of 15 states including Wisconsin. Federal Energy Regulatory Commission, accessed 2026-06-10
  • Regulated utility market: Wisconsin remains a regulated electric market; the PSC regulates electric, gas, and water utilities and requires PSC approval before utilities change rates or undertake major construction such as power plants and transmission lines. Public Service Commission of Wisconsin, accessed 2026-06-10
  • Regulatory posture for data centers: The PSC states that it does not permit or regulate data center construction/operations directly; it regulates the utilities that serve data centers and reviews rates through tariffs, individual contracts, and final orders. Public Service Commission of Wisconsin, accessed 2026-06-10

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

  • Generic MISO queue reforms remain regional rather than data-center-specific: MISO’s queue reform materials describe FERC acceptance of ER24-340 reforms that increased milestone payments, added automatic withdrawal penalties, revised withdrawal penalties, and expanded site-control requirements. These reforms affect Wisconsin through MISO but are not Wisconsin data-center interconnection rules. MISO Help Center, accessed 2026-06-10; FERC, 2025-01-30
  • Large-load interconnection work accelerated in 2026: MISO describes an unprecedented surge in large-load interconnection requests driven by data centers, advanced manufacturing, and other energy-intensive facilities, and says it is using expedited processes such as the Expedited Resource Addition Study and MTEP Expedited Project Review to support timely integration. MISO, accessed 2026-07-17
  • Regional EPR pressure intensified during the refresh window: MISO’s April 2026 Expedited Project Review statistics update reported 19 April-cycle EPR project requests representing more than 5,457 MW of new load additions, underscoring that Wisconsin large-load reviews are occurring inside a broader regional queue surge. MISO, 2026-04-07
  • Wisconsin-specific 2026 large-load interconnection proceeding: The most important current interconnection development is PSC docket 137-CE-221, the Ozaukee County Distribution Interconnection Project. ATC proposes new and uprated 345 kV lines, potential 138 kV lines, and four to five substations across Calumet, Fond du Lac, Ozaukee, Manitowoc, Sheboygan, and Washington counties; PSC says the project was driven by a We Energies load interconnection request that its distribution system could not support. Public Service Commission of Wisconsin, accessed 2026-06-10
  • Cost and schedule: PSC lists the Ozaukee interconnection project’s estimated cost at $1.364 billion to $1.643 billion depending on route, states ATC filed the application in September 2025, found it complete in December 2025, and says the Commission may have until December 2026 to approve, modify, or deny it. Public Service Commission of Wisconsin, accessed 2026-06-10
  • Longer-term regional transmission context: MISO’s Long Range Transmission Planning Tranche 2.1 was approved in 2024 for the Midwest subregion and includes large 765 kV transmission development; ATC’s 2025 ten-year assessment lists Tranche 2.1 projects in or affecting the ATC/Wisconsin footprint, but those are long-run regional projects rather than February-July 2026 Wisconsin data center approvals. MISO, accessed 2026-07-17; ATC, accessed 2026-07-17
  • FERC ordered MISO and the other regional operators to justify or reform large-load rules: On June 18, FERC issued a Section 206 show-cause order to MISO, preliminarily finding its existing tariff deficient for large-load interconnection and directing MISO to explain or propose reforms. FERC required a generation-adequacy response within 30 days and a large-load integration response within 60 days; this began a federal rulemaking track rather than immediately creating a new Wisconsin interconnection tariff. Federal Energy Regulatory Commission, 2026-06-18; Federal Energy Regulatory Commission order 195 FERC ¶ 61,212, 2026-06-18
  • MISO-specific proposals remain in development: MISO’s Large Load Working Group requested June feedback on a firm-service step-up approach and continued developing large-load reliability requirements. These stakeholder proposals could affect the sequence and conditions under which Wisconsin data centers receive firm service, but they were not final tariff rules as of July 17. MISO, 2026-06-10; MISO, accessed 2026-07-17

3) Ratepayer protection (tariffs, cost allocation, PSC orders)

  • We Energies data center tariff approved with major modifications: On April 24, 2026, PSC took up We Energies’ Very Large Customer (VLC) and Bespoke Resources tariff application in docket 6630-TE-113 and approved it with changes intended to protect existing customers and increase transparency. Public Service Commission of Wisconsin, 2026-04-24
  • Key We Energies tariff guardrails: PSC extended the VLC minimum initial term to 15 years, lowered the eligibility threshold from 500 MW to 100 MW, required tariff revisions addressing transmission cost-shifting risk, removed a capacity-only option under which data centers would have paid 75% of generating-facility costs, approved a Full-Benefits model requiring VLCs to pay 100% of their costs, and ordered additional reporting requirements. Public Service Commission of Wisconsin, 2026-04-24
  • Alliant/Meta service agreement approved with future-tariff requirement: On May 7, 2026, PSC modified and approved Alliant Energy’s Electric Service Agreement application for a Beaver Dam data center customer in docket 6680-TE-115, strengthened termination and reporting provisions, imposed financial safeguards, required contribution to the statewide energy-efficiency and renewable-energy program, approved renewable energy procurement agreements, and ordered Alliant to file a stand-alone large-load tariff for future data center customers. Public Service Commission of Wisconsin, 2026-05-07
  • Public transparency concern: PSC commissioners criticized the one-off/confidential contract approach and required a standardized future framework; Wisconsin Watch reported that the approved Alliant/Meta deal covers a Beaver Dam campus projected at about 220 MW peak load, six to eight times Beaver Dam’s current peak. Public Service Commission of Wisconsin, 2026-05-07; Wisconsin Watch, 2026-05-07
  • We Energies/Oracle credit-security dispute moved to court: We Energies, Vantage, and Cloverleaf asked the PSC on June 10 to loosen the A- credit threshold and security requirements in docket 6630-TE-113; they said Oracle’s then-BBB rating could require more than $100 million per year in cash or letters of credit. Oracle sued the PSC in Ozaukee County Circuit Court on June 19. The PSC allowed the statutory reconsideration period to expire without reopening the decision in July, leaving the safeguards in force while the suit proceeds. Wisconsin Watch, 2026-06-12; Wisconsin Watch, 2026-06-24; Wisconsin Watch, 2026-07-09
  • Oracle downgrade reinforces the live credit issue: S&P lowered Oracle from BBB to BBB- on July 9, the lowest investment-grade rung and farther below the PSC’s A- threshold. The downgrade did not alter the tariff automatically, but it increased the gap that Oracle would have to cover with financial guarantees under the challenged order. Wisconsin Watch, 2026-07-15
  • Xcel filed a third Wisconsin large-load tariff: Northern States Power Company-Wisconsin filed a proposed Very Large General Time-of-Day Service tariff on June 22 for new customers or expansions of at least 100 MW. Xcel proposes 15-year commitments, minimum monthly payments, exit charges, financial security, and recovery of 100% of service costs from the large customer. Xcel reported 2.9 GW of pending Wisconsin large-load requests, acknowledged that some were speculative, and asked for a PSC decision by February 2027; review remained pending at the cutoff. Xcel Energy, 2026-06-22; Wisconsin Public Radio, 2026-06-24

4) Generation adequacy (projects, storage, shortfall concerns)

  • WEC/We Energies load-driven buildout: WEC Energy Group said already-planned Microsoft Mount Pleasant and Vantage Port Washington loads drive a 3.9 GW five-year demand increase, and that additional development at those sites could add another 4-5 GW of capacity. Wisconsin Public Radio, 2026-05-07
  • Nearly 3 GW resource plan tied to data-center demand: We Energies is asking PSC to approve a $5.5 billion plan to add almost 3 GW of power to the grid, including seven solar projects and two new gas-fired plants, while WEC’s broader five-year capital plan includes $12.6 billion for renewables and $7.4 billion for gas-fired power plants and natural gas storage. Wisconsin Public Radio, 2026-05-07
  • Coal/nuclear/gas planning tension: WPR reported that WEC delayed retirement of Oak Creek coal units, planned to replace Point Beach nuclear power purchases with gas-fired units because of high energy prices, and paused near-term carbon-reduction goals amid tightened supply. Wisconsin Public Radio, 2026-05-07
  • Backup generation and air permits issued: DNR issued Vantage minor-source construction permit 25-MIN-094 and initial operation permit 24618528A-F01 on June 12 for 45 diesel-fired emergency generators at Port Washington and released a supplemental environmental analysis the same day. The permits replaced the preliminary status recorded in the prior refresh. Sierra Club sued DNR on July 10, alleging that a full environmental impact statement was legally required; DNR’s permits remained effective and the case remained pending at the cutoff. Wisconsin Department of Natural Resources, 2026-06-12; Wisconsin Public Radio, 2026-07-10

5) Utility load forecasts and planning (data centers)

  • MISO regional forecast shifted upward in April 2026: MISO’s April 13, 2026 Long-Term Load Forecast summary says the region is seeing rapid load growth driven primarily by large, concentrated loads, that its current trajectory is roughly aligned with the high end of the 2024 forecast range, and that data-center load is now anticipated to exceed twice the level in the 2024 LTLF. MISO, 2026-04-13
  • Near-term data-center load uncertainty is material: MISO’s 2026 forecast identifies expected 8-14 GW of data-center growth in 2026-2027 as a key indicator of how quickly data-center-driven demand can materialize, with high-, medium-, and low-confidence projects handled differently in the trajectory. MISO, 2026-04-13
  • We Energies territory: WEC’s May 2026 comments put the Microsoft Mount Pleasant and Vantage Port Washington pipeline at 3.9 GW of demand growth over five years, with potential to double that demand through additional development at the same sites. Wisconsin Public Radio, 2026-05-07
  • Alliant territory: In approving the Meta/Beaver Dam service agreement, PSC required Alliant to develop a stand-alone large-load tariff for future data-center customers; WPR reported PSC Commissioner Kristy Nieto saying there were 12 other data center plans in Alliant’s service territory. Public Service Commission of Wisconsin, 2026-05-07; Wisconsin Public Radio, 2026-05-12
  • Clean Wisconsin estimate in PSC/public debate: WPR reported a 2025 Clean Wisconsin analysis estimating that Mount Pleasant and Port Washington data centers would require enough electricity to power 4.3 million homes, and testimony filed with PSC said those two projects could double We Energies’ electricity demand by 2030. Wisconsin Public Radio, 2026-05-12
  • PSC draft Strategic Energy Assessment quantifies the statewide jump: The draft assessment released in late June projects Wisconsin peak demand rising from 14.2 GW to more than 20 GW by 2032, an increase above 40%; more than 72% of the forecast peak-load increase is associated with the Microsoft Mount Pleasant, Oracle Port Washington, and Meta Beaver Dam developments. The draft was subject to revision before a final report expected in fall 2026. Public Service Commission of Wisconsin Strategic Energy Assessment page, accessed 2026-07-17; Wisconsin Public Radio, 2026-07-07
  • Generation additions in the draft assessment: Wisconsin utilities reported plans to add 14.2 GW of generation capacity through 2032, including 5.4 GW of natural gas, 5.2 GW of solar, 1.3 GW of wind, and 2.25 GW of storage. The PSC draft projects a 2032 generation mix of 50% natural gas, 17% wind, 16% solar, and 3% coal; these are planning projections, not approvals of every listed resource. Public Service Commission of Wisconsin Strategic Energy Assessment page, accessed 2026-07-17; Wisconsin Public Radio, 2026-07-07

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

  • PSC path is utility service, not direct data center regulation: PSC’s Wisconsin data center guidance describes utility service through tariffs, individual contracts, and utility construction proceedings rather than direct PSC permitting of data center facilities. Public Service Commission of Wisconsin, accessed 2026-06-10
  • Vantage / Port Washington clean-energy claims remain utility-backed: Vantage says the Lighthouse campus will receive power from We Energies, with 70% of campus power originating from zero-emission resources and the remaining energy matched annually with renewable purchases; this is not documented as behind-the-meter generation in the public sources reviewed. Vantage Data Centers, accessed 2026-06-10
  • Alliant / Meta renewable procurement: PSC approved Renewable Energy Procurement Agreements for the Beaver Dam data center customer as part of the Alliant service-agreement decision. Public Service Commission of Wisconsin, 2026-05-07
  • MISO co-location rules remain unresolved: MISO continued work on how co-located load and generation behind one point of interconnection should participate and register. Its July 9 issue page says existing processes separately register new load and study generation interconnection, so no new MISO rule yet creates an automatic behind-the-meter path for Wisconsin data centers. MISO, 2026-07-09

7) Transmission constraints and upgrades affecting siting

  • Ozaukee / Port Washington: PSC docket 137-CE-221 is a major data-center-related transmission proceeding, with the applicant tying need to a We Energies load interconnection request and estimating $1.364-$1.643 billion in project cost. Public Service Commission of Wisconsin, accessed 2026-06-10
  • ATC statewide data-center transmission work: WPR reported in April that American Transmission Co. was planning about $2 billion in transmission projects serving data centers in Mount Pleasant, Port Washington, and Beaver Dam, and that We Energies expected data centers to cover $564 million in transmission costs in 2027 and 2028. Wisconsin Public Radio, 2026-04-17
  • Transmission cost-shift issue incorporated into tariff design: PSC’s April 24 We Energies tariff decision explicitly required revisions addressing the risk of transmission cost shifting from data center customers to existing customers. Public Service Commission of Wisconsin, 2026-04-24
  • Beaver Dam / Alliant: PSC’s Alliant decision strengthens customer protections for the Meta/Beaver Dam contract and requires a public large-load tariff for future data center customers, shifting the regulatory posture away from case-by-case confidential contracts. Public Service Commission of Wisconsin, 2026-05-07
  • Ozaukee agricultural-impact and construction schedule: DATCP issued its agricultural impact statement for the Ozaukee interconnection project in June; the published schedule anticipates land acquisition beginning in winter 2026, construction beginning in winter 2026, and service by December 2027. PSC still had not issued its certificate decision by July 17. Wisconsin Department of Agriculture, Trade and Consumer Protection, 2026-06-16; Public Service Commission of Wisconsin, accessed 2026-07-17
  • ATC challenged MISO’s separate competitive transmission award: ATC filed a June 23 FERC complaint seeking review of MISO’s solicitation for the Wisconsin Southeast Competitive Transmission Project, a Tranche 2.1 project whose substations and lines overlap parts of the eastern-Wisconsin buildout. The complaint asks FERC to require a new evaluation or award the full project to ATC; it did not itself suspend PSC docket 137-CE-221, and its eventual schedule effect remained uncertain. American Transmission Co., 2026-06-23; Wisconsin Watch, 2026-07-15

Notes and gaps