2024

10-Year
Assessment

Generation interconnections

The size and location of new or expanded power plants can have significant impacts on the transmission system. These impacts are evaluated in MISO Definitive Planning Phase (DPP) process.  Information on the status, as of October 10, 2024, of generation requests in the ATC portion of the MISO generation interconnection queue is provided in this section. There continues to be significant activity in ATC’s footprint, ranging from newly proposed generation projects to cancellation of previously proposed generation projects. 

There are two key aspects in determining the total impacts a proposed new generator may have on the transmission system:

  • impacts of interconnecting the new generator to the transmission system and 
  • impacts of using the transmission system to deliver power from the new generator. 

As described in MISO’s Attachment X process, a generator interconnection study is performed in three phases which are all within the Definitive Planning Phase (DPP): an Interconnection System Impact Study (Phase 1, 2 and 3), and an Interconnection Customer Interconnection Facilities Study (Phase 2 and 3). The Network Upgrade Facilities Study begins after the System Impact Study is completed in Phase 3. 

The Interconnection System Impact Study includes a determination of whether the proposed generator and other nearby generators will remain connected to the system under various disturbance situations, such as line trips and equipment failures and includes a fault duty analysis to determine whether existing system equipment can accommodate the increased short circuit fault duty caused by the new generator. Additionally, the System Impact Study will identify solutions for any thermal, stability or fault duty deficiencies. 

Delivery impacts are assessed during the DPP portion of the interconnection study process using the MISO deliverability methodology, which determines whether the output of a new generator is deliverable to the MISO energy market and to what percent if not wholly deliverable. Whatever portion of the new generator that is deliverable may then be used as a Network Resource by Network Customers through MISO’s Module E Resource Adequacy procedures. 

The Interconnection Customer Interconnection Facilities Study is conducted in Phase 2 and 3.  It specifies and estimates the time and cost of the equipment, engineering, procurement, and construction of the interconnection facility upgrades identified in the earlier interconnection studies. 

The Network Upgrade Facilities Study is conducted after Phase 3. It specifies and estimates the time and cost of the equipment, engineering, procurement and construction of the network system upgrades identified in the earlier interconnection studies. 

The results of the interconnection studies are needed to develop a comprehensive picture of the transmission facilities that will be required for a proposed generator. Only transmission facilities that result from generators with a signed Interconnection Agreement are included in the 10-Year Assessment models. 

The first portion of this section provides the status of the generation queue within our service territory. The second portion of this section describes proposed generation projects for which final interconnection studies have been completed. The third portion of this section describes some of the implications associated with interconnecting generation at various locations within our service territory. 

ATC Portion of MISO Generation Queue

Over the last ten years (2014 through September 2024), 24 new generators have gone into service and five uprates or replacements to existing generators have been completed, totaling over 3000 MW. These generators are included in Table PR-26. 

Table PR-26: Generator Requests From Past Ten Years Now In-Service

In-Service Date Queue Number and Name Project Capacity (MW) 
3/4/2016 J382 RockGen uprate 48.3 
4/27/2016 J241 Twin Falls Hydro uprate 3.7 
5/1/2017 J384 Christiana uprate 21 
5/8/2017 J557 Garden Corners Solar 0.9 
11/4/2017 J395 Quilt Block Wind Farm 98 
3/31/2019 J703 Kuester 131.7 
3/31/2019 J704 Mihm 56.5 
5/14/2020 J390 & J760 West Riverside 732 
10/28/2019 J831 Port Washington uprate 40  
11/2/2020 J886 Two Creek Solar 150 
9/13/2021 J505 Point Beach Solar Energy Center 100 
12/1/2021 J870 Badger Hollow 1 150 
1/7/2022 J928 Garden Wind 80 
6/2/2022 J1183 Garden Solar II 1.35 
10/17/2022 J864 Bear Creek 50 
1/20/2023 J1188 N Rock Solar 50 
1/20/2023 J986 Wood County Solar 150 
4/4/2023 J855 Red Barn 92 
7/27/2023 R1010 Weston RICE 133 
12/23/23 J871, Badger Hollow II 150 
02/09/24 J1000, Cassville Solar 50 
02/09/24 J1304, Paddock Solar 65 
02/09/24 J1305, Albany Solar 50 
02/27/24 J1002, Wautoma Solar 99 
02/27/24 J1003, Beaver Dam Solar 50 
03/01/24 J1171, Springfield Solar 100 
04/12/24 J1153, Onion River Solar 150 
04/16/24 J1154, Crawfish River Solar 75 
05/29/24 J947, Grant County Solar 200 
Total   3037 

Table PR-27 lists the proposed generators in the generation queue for our service territory as of October 09, 2024, who have not yet signed the Generator Interconnection Agreement (GIA). It is important to keep in mind that the status of queued projects changes often as projects enter and withdraw from the queue, sign generator interconnection agreements and start construction. This table lists each proposed generation project and summarizes them by zone and MW amount. These proposed projects also are shown by approximate location in Figure PR-9.

As shown, the total capacity of proposed generators in this portion of the queue is roughly 12.57 GW. Of this proposed capacity, natural gas fired units reflect 26.5 percent, wind 8.5 percent, solar 33 percent, storage 27.7 percent, and hybrid 4.3 percent (see Figure PR-10). The hybrid units are combination of storage with wind or solar. Of the proposed capacity, 31.5 percent is in Zone 1, 10.9 percent is in Zone 2, 19.5 percent is in Zone 3, 13.5 percent is in Zone 4, and 24.6 percent is in Zone 5. 

Table PR-27: Proposed Projects Active in the Generation Queue as of October 09, 2023

Zone Queue # County Project capacity (MW) Interconnection voltage (kV) Generator technology and fuel 
J986_S1018 Wood 75 138 STORAGE 
J1002_S1024 Waushara 50 138 STORAGE 
J1752 Portage 148.1 138 SOLAR 
J2099 Portage 399.03 345 SOLAR 
J2107 Portage 399.03 345 SOLAR 
J2117 Wood 138 STORAGE 
J2185 Portage 399.03 345 SOLAR 
J2193 Waushara 100 138 HYBRID 
J2277 Portage 138 STORAGE 
J2326 Outagamie 150 345 STORAGE 
J2335 Portage 200 115 STORAGE 
J2345 Marathon 150 345 WIND 
J2365 Portage 160 345 STORAGE 
J2366 Portage 160 345 SOLAR 
J2520 ADAM 200 138 SOLAR 
J2557 Wood 100 345 STORAGE 
J2559 Wood 200 345 SOLAR 
J2609 Waushara 80 138 SOLAR 
J2833 Wood 40 69 HYBRID 
J2870 Sawyer 243.6 345 SOLAR 
J2944 Wood 350 345 GAS 
J3204 Clark 208 345 WIND 
J2439 Marathon 50 345 STORAGE 
J3469 Marathon 100 115 WIND 
1 Total 3962 
J928_S1015 Delta 55 138 SOLAR 
J1750 Marquette 149.7 138 SOLAR 
J2029 Marquette 62.5 138 SOLAR 
J2316 Dickinson 77.5 138 SOLAR 
J2354 Marinette 65 69 STORAGE 
J2678 Delta 150 138 SOLAR 
J3281 Marquette  170 138 WIND 
J3800 Baraga 1.8 138 GAS 
J3756 Marquette  4.2 138 GAS 
J3638 Dickinson 50 138 STORAGE 
J3641 Dickinson 100 138 SOLAR 
J3642 Dickinson 60 138 SOLAR 
J3648 Baraga 120 120 HYBIRD 
J3649 Houghton 200 138 HYBIRD 
J3514 Chippewa 100 69 SOLAR 
2 Total 1366 
J864_S1016 Richland 25 69 STORAGE 
J850_S1006 Rock 75 138 STORAGE 
J1188_S1025 Rock 25 69 STORAGE 
J1000_S1023 Grant 25 138 STORAGE 
J1003_S1034 Dodge 25 69 STORAGE 
J1305_S1033 Green 25 138 STORAGE 
J1304_S1035 Rock 33 138 STORAGE 
J1732 Columbia 98.4 138 SOLAR 
J1824 Columbia 67 138 SOLAR 
J1931 Iowa 40 345 WIND 
J1935 Dane 50 138 SOLAR 
J1943 Columbia 200 345 SOLAR 
J1993 Columbia 99 345 SOLAR 
J2304 Columbia 400 345 STORAGE 
J2324 Winnebago 35 69 HYBRID 
J2423 Columbia 300 345 STORAGE 
J2429 Dane 50 69 SOLAR 
J2666 Walworth 100 138 SOLAR 
J2947 Rock 205 138 GAS 
J3152 Green 160 138 GAS 
J3156 Rock 60 138 GAS 
J3162 Rock 100 138 STORAGE 
J3639 Columbia 250 345 WIND 
3 Total 2447 
J2055 Sheboygan 100 138 SOLAR 
J2148 Outagamie 150 138 SOLAR 
J2211 Brown 200 138 STORAGE 
J2537 Shawano 100 345 STORAGE 
J2544 Shawano 95 345 SOLAR 
J2834 Fond du Lac 50 69 HYBRID 
J3151 Sheboygan 150 345 GAS 
J3155 Winnebago 150 138 GAS 
J3160 Fond du Lac 100 345 STORAGE 
J3161 Sheboygan 100 138 STORAGE 
J3466 Winnebago 100 138 SOLAR 
R1049 Sheboygan 404.5 345 GAS 
4 Total 1699.5 
J1895 Kenosha 200 138 STORAGE 
J1934 Kenosha 150 138 STORAGE 
J2891 Kenosha 50 138 SOLAR 
J3006 Milwaukee 300 345 STORAGE 
J3330 Kenosha 705 345 GAS 
J3332 Calumet  150 345 WIND 
J3785 Kenosha 200 345 STORAGE 
J3784 Ozaukee 200 345 STORAGE 
R1053 Milwaukee 1138.5 345 GAS 
5 Total 3093.5 
Grand Total                 12,568  

Table PR-28: Requests Previously in the Generation Queue Which Have been Withdrawn/Removed between June 1, 2022 and October 09, 2023

Zone Queue # County Project capacity (MW) Interconnection voltage (kV) Generator technology and fuel Date Withdrawn 
J1938 Portage 150 345 SOLAR 9/30/2024 
J1945 Portage 150 345 SOLAR 9/30/2024 
J2293 Adams 50 69 SOLAR 9/30/2024 
J1510 Wood 100 345 SOLAR 11/17/2023 
1 Total 450 
J1884 Columbia 200 345 STORAGE 9/30/2024 
J1964 Columbia 90 345 STORAGE 9/30/2024 
J1983 Dane 25 138 STORAGE 9/30/2024 
J2188 Columbia 99 345 SOLAR 9/30/2024 
J2271 Columbia 200 345 SOLAR 9/30/2024 
J1042 Walworth 180 138 SOLAR 9/8/2023 
J1497 Jefferson 125 138 SOLAR 6/29/2023 
J1708 Grant 75 138 SOLAR 6/22/2023 
J1735 Rock 75 138 SOLAR 6/22/2023 
J1843 Dane 12 138 GAS 6/22/2023 
3 Total 1081 
J1994 Fond du Lac 97.088 138 SOLAR 9/30/2024 
J1996 Shawano 99 138 HYBRID 9/30/2024 
J2074 Outagamie 75 138 STORAGE 9/30/2024 
J2218 Manitowoc 150 138 STORAGE 9/30/2024 
J1567 Outagamie 150 345 SOLAR 6/22/2023 
4 Total 571 
Grand Total 2102 

Table PR-29: Active Projects in the Generator Queue in Construction or waiting construction as of October 09, 2023. It includes projects with signed GIA.

Zone Queue # County Project capacity (MW) Interconnection voltage (kV) Generator technology and fuel 
J732 Douglas 562 345 GAS 
J1502 Juneau 225 345 SOLAR 
J1508 Marathon 98.9 115 WIND 
J1573 Portage 250 115 SOLAR 
J1751 Wood 150.5 138 SOLAR 
1 Total 1,286 
J1251 Marquette 100 138 SOLAR 
J1814 Dickinson 22.5 138 SOLAR 
2 Total 123 
J818 Jefferson 149 138 SOLAR 
J850 Rock 250 138 SOLAR 
J947_S1017 Grant 100 138 STORAGE 
J1214 Dane 300 345 SOLAR 
J1326 Dane 75 345 STORAGE 
J1374 Grant 67.2 138 WIND 
J1377 Rock 98.56 345 SOLAR 
J1410 Dane 300 345 SOLAR 
J1411 Dane 75 345 STORAGE 
J1460 Rock 200 138 HYBRID 
J1483 Iowa 99 345 WIND 
J1629 Columbia 200 345 SOLAR 
J1706 Green 100 138 SOLAR 
J1746 Columbia 150 138 SOLAR 
J1773 Iowa, Lafayette 300 345 WIND 
J1779 Dane 200 345 HYBRID 
J1781 Iowa, Lafayette 300 345 WIND 
3 Total 2,964 
J1101 Manitowoc 20 138 STORAGE 
J1253 Fond du Lac 100 345 SOLAR 
J1513 Waupaca 300 138 SOLAR 
J1615 Oconto 150 138 SOLAR 
J1716 Fond du Lac 100 345 SOLAR 
J1745 Winnebago 100 138 SOLAR 
J1793 Sheboygan 75 138 SOLAR 
4 Total 845 
J878 Kenosha 200 138 SOLAR 
J878_S1005 Kenosha 60 138 STORAGE 
J1316 Kenosha 50 138 STORAGE 
J1778 Kenosha 100 138 SOLAR 
5 Total 410 
Grand Total 5,628 
Includes projects with signed GIA.

Link to publicly posted MISO generation queue

Implications of generation development

From a transmission perspective, the ability of the transmission system to accommodate new generation is a function of stability, power flow and short circuit analyses. For certain generation technologies, harmonics, fast control interactions and voltage fluctuations may need to be considered as well. In most instances, new generation will require certain transmission system reinforcements to interconnect and deliver the generation output. In a few specific instances, new generation can be beneficial to the transmission system, even deferring or eliminating the need for transmission reinforcements that would be necessary absent the new generation. The ability of generation to defer or eliminate the need for transmission reinforcements also can be a function of the generation location, number of generators, and/or expected generator capacity factor. 

In this section, a general zone-by-zone evaluation of the likelihood of needing or deferring transmission reinforcements for various generator locations is provided. The purpose of these evaluations is to provide a cursory indication to the generation market of the likely magnitude of the impact and the transmission reinforcements that would likely be needed by general location. 

Zone 1

In Zone 1, about 31.5 percent (~3,962 MW, Table PR-27) of the proposed generation is located near the 345-kV infrastructure. Based on studies that we have conducted for proposed generation interconnections to date some transmission reinforcements are likely to be required for any significant generation development. The extent and nature of the reinforcements largely would be a function of where the power from the generation is to be delivered.  

The transmission infrastructure in the central portion of Zone 1 includes three 345 kV lines (Gardner Park – Highway 22, Morgan – Highway 22, and Highway 22 – Werner West). These lines significantly strengthen the Weston area, bringing much needed support to the area for both stability and thermal considerations. Furthermore, the new lines included MISO Long Range Transmission plan (LRTP) Tranche 1 will significantly strengthen this area.  

The infrastructure in the southern portion of Zone 1 consists of several 69 kV and 138 kV lines. The existing infrastructure in this portion of Zone 1 is not suitable for significant generation development. 

Three Zone 1 generator projects went in service or are in construction in the last five years. 

Zone 1 Generators In Construction or In Service

Request Size (MW) Type County State Status 
J1002 99 Solar Waushara WI In Service 
J986 150 Solar Wood WI In Service 
R1010 133 Natural Gas Marathon WI In Service 
J732 527.8 Natural Gas Douglas WI In Construction 
J1502 225 Solar Juneau WI In Construction 
J1508 98.9 Wind Marathon WI In Construction 
J1573 250 Solar Portage WI In Construction 
J1751 150.5 Solar Wood WI In Construction 
Zone 1 generators in construction or in service in the last 5 years.

Zone 2

ATC has seen substantial interest in siting generators in the Upper Peninsula of Michigan. One of the major challenges proposed generation in the Upper Peninsula will face is the limited transmission infrastructure to interconnect and deliver the energy produced by these generators. Since the Upper Peninsula transmission grid was primarily designed to serve local load, transmission upgrades may be required to accommodate these proposed plants.

There are areas in Zone 2, which currently or will eventually need transmission reinforcements where smaller generation projects could be beneficial in terms of deferring transmission expenditures. The allowable capacity and potential impacts of such generation would depend on location. Impacts like thermal, stability and fault duties would need to be evaluated through the DPP process.

The following table lists Zone 2 generator projects in service or in construction in the last five years.

Zone 2 Generators In Construction or In Service

Request Size (MW) Type County State Status 
J703 131.7 Natural Gas Marquette County MI In Service 
J704 56.5 Natural Gas Baraga County MI In Service 
J928 80 Wind Delta County MI In Service 
J1183 1.4 Solar Delta County MI In Service 
J1251 100 Solar Marquette County MI In Construction 
J1814 22.5 Solar Dickinson MI In Construction 
Zone 2 generators in construction or in service in the last five years.

Zone 3

In Zone 3, about 19.5 percent (~2,447 MW, Table PR-27) of the active generation in the queue is at various locations throughout the zone. In recent cycles, there are more proposals in Dane and Columbia Counties and along the Cardinal-Hickory Creek Transmission Line Project corridor (especially in Iowa and Grant Counties). 

Along with the Cardinal-Hickory Creek Transmission Line Project, completion of the Badger Coulee Transmission Line Project and generation retirements seem to be the major drivers for new generator developments in those locations. Furthermore, the new line, terminating at Columbia 345-kV Substation, included MISO Long Range Transmission plan (LRTP) Tranche 1 will significantly strengthen the area.  

 

Similarly, the southeast portion of Zone 3 continues to be an attractive location for siting generation. However, generation studies completed in the southwest corner of the state have demonstrated that siting large amounts of generation in rural areas may require substantial upgrades to the transmission system to ensure reliable operation. 

The following table lists Zone 3 generator projects in service or in construction in the last five years. 

Zone 3 Generators In Construction or In Service

Request Size (MW) Type County, State Status 
J390 702 Natural Gas Rock WI In Service 
J760 30 Natural Gas Rock WI In Service 
J855 100 Wind Iowa WI In Service 
J864 50 Solar Richland WI In Service 
J870 200 Solar Iowa WI In Service 
J871 100 Solar Iowa WI In Service 
J947 200 Solar Grant WI In Service 
J1000 50 Solar Grant WI In Service 
J1003 50 Solar Dodge WI In Service 
J1154 75 Solar Jefferson WI In Service 
J1188 50 Solar Rock WI In Service 
J1304 65 Solar Rock WI In Service 
J1305 49.9 Solar Green WI In Service 
J818 149 Solar Jefferson WI In Construction 
J850 250 Solar Rock WI In Construction 
J947_S1017 100 Storage Grant WI In Construction 
J1214 300 Solar Dane WI In Construction 
J1326 75 Storage Dane  WI In Construction 
J1374 67.2 Wind Grant WI In Construction 
J1377 98.56 Solar Rock WI In Construction 
J1410 300 Solar Dane WI In Construction 
J1411 75 Storage Dane WI In Construction 
J1460 200 Hybrid Rock WI In Construction 
J1483 99 Wind Iowa WI In Construction 
J1629 200 Solar Columbia WI In Construction 
J1706 100 Solar Green WI In Construction 
J1746 150 Solar Columbia WI In Construction 
J1773 300 Wind Iowa, Lafayette WI In Construction 
J1779 200 Hybrid Dane WI In Construction 
J1781 300 Wind Iowa, Lafayette WI In Construction 
Zone 3 generators in construction or in service in the last five years

Zone 4

Generation has been proposed in various locations in Zone 4. Generation could be beneficial in a few areas depending on the capacity of such generation and exact location. Given the nature of the issues in Zone 4, it is unlikely that new generation will significantly alter the need for the major transmission reinforcements contemplated in that zone. In recent generation studies, more stress on the 138-kV path from North Appleton to South Fond Du Lac is observed and may need substantial reinforcements if the new generation projects move forward. This path is located west of Lake Winnebago and is parallel to 345-kV from North Appleton to South Fond Du Lac. 

One area where generation could defer the need for transmission reinforcements is in Door County, provided such generation is small-scale and appropriately located. Currently, the northern portion of the county is served radially and electric service is subject to interruption for the loss of the single 69 kV line serving the area. The voltage profile in Door County is projected to precipitate the need for reinforcements in the future. Small-scale generation potentially could defer some of these reinforcements. 

The following table lists Zone 4 generator projects in service or in construction in the last five years. 

Zone 4 Generators In Construction or In Service

Request Size (MW) Type County, State State Status 
J505 99 Solar Manitowoc Wis. WI In Service 
J886 150 Solar Manitowoc Wis. WI In Service 
J1153 150 Solar Sheboygan Wis. WI In Service 
J1171 100 Solar Dodge  WI In Service 
J1101 20 Storage Manitowoc  WI In Construction 
J1253 100 Solar Fond du Lac  WI In Construction 
J1513 300 Solar Waupaca WI In Construction 
J1615 150 Solar Oconto WI In Construction 
J1716 100 Solar Fond du Lac WI In Construction 
J1745 100 Solar Winnebago WI In Construction 
J1793 75 Solar Sheboygan WI In Construction 
Zone 4 generators in construction or in service in the last five years.

Zone 5

With proposed development of Paris 345-kV Substation, and developments related to Microsoft’s large data center load in Southeast Wisconsin are expected to get some reinforcement to the local transmission capacity and that may make it attractive for new generators to locate there. In the MISO and PJM generation studies, there seems to be a possible need for an additional 345-kV tie line between ATC and Commonwealth Edison (ComEd) or local 345-kV reinforcement to handle regional flows driven by new generation and retirements. 

The following table lists Zone 5 generator projects in service or in construction in the last five years. 

Request Size (MW) Type County, State State Status 
J831 40 Gas Ozaukee  WI In Service 
J878 200 Solar Kenosha  WI In Construction  
J878_S1005 60 Storage Kenosha  WI In Construction  
J1316 50 Storage Kenosha  WI In Construction  
WI 
J1778 100 Solar Kenosha WI In Construction