What changed in this filing

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Item 1. Business

2024-02-16 compared with 2023-02-24 · 94 added, 74 removed, 387 unchanged (30% of the section changed)

12 unchanged sentences

WPL also sells electricity to wholesale customers in Wisconsin.

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3) CORPORATE SERVICES - provides administrative services to Alliant Energy, IPL, WPL and AEF.

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ATC Holdco LLC holds an interest in Duke-American Transmission Company, LLC, a joint venture between Duke Energy Corporation and ATC, that owns electric transmission infrastructure in North America.

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Corporate Venture Investments - includes various minority ownership interests in regional and national venture funds, including a global coalition of energy companies working together to help advance the transition towards a cleaner, more sustainable, and inclusive energy future, by identifying and researching innovative technologies and business models within the emerging energy economy.

Non-utility Wind Farm - includes a 50% cash equity ownership interest in a 225 MW non-utility wind farm located in Oklahoma.

Sheboygan Falls Energy Facility - is a 347 MW, simple-cycle, natural gas-fired EGU near Sheboygan Falls, Wisconsin, which is leased to WPL for an initial period of 20 years ending in 2025.

Sheboygan Falls Energy Facility - is a 347 MW, simple-cycle, natural gas-fired EGU near Sheboygan Falls, Wisconsin, which is currently leased to WPL through 2039.

Refer to Note 10 for additional information on WPL’s Sheboygan Falls Energy Facility lease.

Travero - is a diversified supply chain solutions company, including a short-line rail freight service in Iowa;

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freight brokerage services;

wind turbine blade recycling services;

and a rail-served warehouse in Iowa.

Development-ready Sites - includes various rail-served and ready-to-build manufacturing and industrial sites throughout Iowa and Wisconsin, with access to various airports, interstate freeways and Alliant Energy’s electric services.

INFORMATION RELATING TO ALLIANT ENERGY ON A CONSOLIDATED BASIS

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This leadership provides strong support for sustained growth of both employee and public safety programs and initiatives.

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Public safety is equally important as we interact with our customers to provide energy to their homes and businesses.

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• healthcare and insurance benefits, including medical, vision, dental, life, short-term disability, and long-term disability insurance;

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• health savings and flexible spending accounts;

• enhanced offerings to support the well-being of employees and their families;

• paid time off to use for vacation, personal time, sick time, holidays, bereavement, jury duty, military leave, parental leave, maternity leave, and adoption leave;

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• legal planning assistance;

• Employee Assistance program;

• tuition reimbursement;

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• Volunteer Grants and Matching Gifts program.

Diversity, Equity and Inclusion (DE&I) - A diverse, equitable and inclusive workplace is crucial for the success and retention of our employees, to attract future talent and to execute our purpose-driven strategy to serve our customers and build stronger communities.

Annually, Alliant Energy awards up to 25 scholarships to children of its current employees and eligible retirees who have achieved excellent records in high school who are pursuing a higher education.

Scholarship award recipients may enroll in any accredited two- or four-year college, university or vocational-technical school in the U.S.

Diversity, Equity, Inclusion and Belonging (DEI&B) - A diverse, equitable and inclusive workplace where everyone feels like they belong is crucial for the success and retention of our employees, to attract future talent and to execute our purpose-driven strategy to serve our customers and build stronger communities.

It is one of our Values - “Care for others:

Together we create a workplace where people feel like they belong and can use their unique backgrounds, talents and perspectives to their fullest potential.” Alliant Energy is driven by DE&I and believes the achievement of its strategic objectives can only be achieved with a focused and engaged workforce.

Together we create a workplace where people feel like they belong and can use their unique backgrounds, talents and perspectives to their fullest potential.” Alliant Energy is driven by DEI&B and believes the achievement of its strategic objectives can only be achieved with a focused and engaged workforce.

Alliant Energy’s corporate officers group currently has approximately 44% gender diversity and 25% ethnic diversity.

Our efforts to create a diverse and inclusive workforce have focused on reducing bias, building diverse teams, and listening and acting on employee feedback, and include:

Our efforts to create a diverse, equitable and inclusive workplace have focused on reducing bias, building diverse teams, and listening to and acting on employee feedback, and include:

• learning opportunities for employees, such as inviting employees to participate in area diversity summits and supporting company-wide listening sessions, speakers and programs;

• capturing and acting upon employee feedback through employee sentiment surveys;

• Employee Resource Groups that foster a diverse and inclusive workplace that supports employee well-being while promoting professional development and enhancing community relationships;

• a DE&I Leadership Team that partners with the Human Resources recruiting department and hiring managers to attract more diverse applicants that represent the diversity of the communities we serve.

Our DE&I initiatives also include a focus on building a diverse Board of Directors.

• Employee Resource Groups that foster a diverse, equitable and inclusive workplace that supports employee well-being while promoting professional development and enhancing community relationships;

• a DEI&B Leadership Team that partners with the Human Resources department and hiring managers to attract more diverse applicants that represent the diversity of the communities we serve.

Our DEI&B initiatives also include a focus on building a diverse Board of Directors.

We believe it is in our shareowners’ best interest to have a diverse Board representing a wide breadth of experiences and perspectives.

Our Board currently has approximately 40% gender diversity and 20% ethnic diversity.

Our 2022 DE&I accomplishments include:

Our 2023 DEI&B accomplishments include:

• received a perfect score on the Corporate Equality Index administered by the Human Rights Campaign Foundation to benchmark LGBTQ+ rights, policies and practices;

• selected for the 2023 Bloomberg Gender-Equality Index;

• held our third annual Day of Understanding, with 85% voluntary company-wide participation, where leaders facilitated conversations around creating a culture of inclusion and belonging, helping to ensure employees are seen, heard and valued;

• all people-leaders completed training on reducing unconscious bias in the interview process.

• held our fourth annual Day of Understanding, with 88% voluntary company-wide participation, where leaders facilitated conversations around creating a culture of inclusion and belonging, helping to ensure employees are seen, heard and valued.

Alliant Energy’s short- and long-term incentive compensation plans include diversity metrics to drive leadership accountability for efforts to advance a diverse and inclusive culture.

Talent Development and Workforce Readiness - We support employees in the growth of their careers through several training opportunities and development programs.

These include tuition reimbursement, online, instructor-led and on-the-job learning formats, as well as leadership development and succession planning.

In addition, we have an apprenticeship program that combines supervised, structured on-the-job training with related instruction to produce highly skilled trade and technical workers.

Our program builds lifetime skills and comprehensive knowledge in the high-demand technical trades necessary for our success.

The program gives us the flexibility to tailor training to match our needs - training employees in our facilities, on our equipment, and consistent with our safety standards and employee expectations.

These include tuition reimbursement, and online, instructor-led and on-the-job learning formats, as well as leadership development and succession planning.

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As we attract and introduce a diverse pool of candidates to our industry, we have an early careers program that includes apprenticeships, youth programs (high school) and internships (college).

Our programs provide a pipeline of talented students to engage in meaningful, hands-on work experiences.

Our apprenticeship program combines supervised, structured on-the-job training with related instruction to produce highly skilled trade and technical workers, and builds lifetime skills and comprehensive knowledge in the high-demand technical trades necessary for our success.

The apprenticeship program gives us the flexibility to tailor training to match our needs - training employees in our facilities, on our equipment, and consistent with our safety standards and employee expectations.

We instill company Values, methods and procedures from day one.

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Corporate Services, IPL and WPL are subject to regulation by FERC under the Public Utility Holding Company Act of 2005 for various matters including, but not limited to, affiliate transactions, public utility mergers, acquisitions and dispositions, and books, records and accounting requirements.

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Energy Policy Act of 2005 - The Energy Policy Act of 2005 requires creation of an Electric Reliability Organization to provide oversight by FERC.

FERC designated North American Electric Reliability Corporation as the overarching Electric Reliability Organization.

FERC designated North American Electric Reliability Corporation, which also provides oversight of cybersecurity standards, as the overarching Electric Reliability Organization.

Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.

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IUB - IPL is subject to regulation by the IUB for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, the construction of EGUs, and the acquisition, sale or lease of assets with values that exceed 3% of IPL’s revenues.

In 2021, legislation was enacted in Iowa prohibiting counties and cities from regulating the sale of natural gas and propane, which supports IPL’s ability to provide gas utility service to a diversified base of retail customers and industries.

In Iowa, counties and cities are prohibited from regulating the sale of natural gas and propane, which supports IPL’s ability to provide gas utility service to a diversified base of retail customers and industries.

Retail Utility Base Rates - IPL files periodic requests with the IUB for retail rate changes and may base those requests on either historical or forward-looking test periods.

The IUB must decide on requests for retail rate changes within 10 months of the date of the application for which changes are filed.

The IUB must decide on requests for retail rate changes within 10 months of the date of the application for which changes are filed, subject to certain exceptions.

The historical test periods may be adjusted for certain known and measurable changes to capital investments, cost of capital and operating and maintenance expenses consistent with IUB rules and regulations.

In 2021, the IUB adopted rules that establish minimum filing requirements for rate reviews using a forward-looking test period, and a related subsequent proceeding review after the close of the forward-looking test period.

The IUB has rules that establish minimum filing requirements for rate reviews using a forward-looking test period, and a related subsequent proceeding review after the close of the forward-looking test period.

The rules provide that in the subsequent proceeding review, a utility’s actual costs and revenues will be presumed to be reasonably consistent with the forward-looking test period if the utility’s actual return on common equity falls within a standard of reasonableness of 50 basis points above to 50 basis points below the authorized return on common equity.

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In addition, the rules require that IPL must receive an order from the IUB related to the subsequent proceeding review before it can file another rate review.

Energy Efficiency - In accordance with Iowa law, IPL is required to file an EEP every five years with the IUB.

Energy Efficiency - In accordance with Iowa law, IPL is required to file an energy efficiency plan (EEP) every five years with the IUB.

An EEP provides a utility’s plan and related budget to achieve specified levels of electric and gas energy savings.

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IUB approval demonstrates that IPL’s EEP is reasonably expected to achieve cost-effective delivery of the energy efficiency programs.

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As a result, IPL may file for, and the IUB must render a decision on, rate-making principles for certain new EGUs located in Iowa, including any alternative energy production facility (such as a wind or solar facility, as well as battery storage constructed in combination with these facilities), combined-cycle natural gas-fired EGU, and certain base-load EGUs with a nameplate generating capacity of 300 MW or more (such as nuclear-fired generation).

Stand-alone battery storage facilities will be considered for advance rate-making principles on a case-by-case basis.

Advance rate-making principles are also available for the repowering of an alternative energy production facility or certain significant alterations of an existing EGU.

Upon approval of rate-making principles by the IUB, IPL must either construct the EGU or repower the alternative energy production facility under the approved rate-making principles, or not at all.

If rate-making principles are not

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approved by the IUB, IPL may construct the facility, subject to other applicable approvals (such as a GCU Certificate), subject to recovery in future rate reviews.

Electric Generating Unit Environmental Controls Projects - IPL is required to submit an updated emissions plan and budget biennially to the IUB setting out a multi-year plan and budget for managing regulated emissions from its coal-fired EGUs in a cost-effective manner.

If rate-making principles are not approved by the IUB, IPL may construct the facility, subject to other applicable approvals (such as a GCU Certificate), subject to recovery in future rate reviews.

Electric Generating Unit Environmental Controls Projects - At its sole discretion, IPL may submit an updated emissions plan and budget to the IUB setting out a multi-year plan and budget for managing regulated emissions from its coal-fired EGUs in a cost-effective manner.

IPL must simultaneously submit this plan and budget to the Iowa Department of Natural Resources for a determination of whether the plan and budget meet state environmental requirements for regulated emissions.

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Currently, WPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels.

Through 2023, any such deferral is required to be offset against the remaining net book value of Edgewater Unit 5, which is currently expected to be retired by June 1, 2025.

Public Benefits - WPL contributes 1.2% of its annual retail utility revenues to help fund Focus on Energy, Wisconsin’s state-wide energy efficiency and renewable energy resource program.

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Advance Rate-making Principles - Wisconsin law provides Wisconsin utilities with the opportunity to request rate-making principles prior to the purchase or construction of any EGU utilized to serve Wisconsin customers.

WPL is not obligated to file for or accept authorized rate-making principles under Wisconsin law.

WPL is not obligated to file

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for or accept authorized rate-making principles under Wisconsin law.

WPL can proceed with an approved project under traditional rate-making terms or accept authorized rate-making principles under Wisconsin law.

Department of Homeland Security Transportation Security Administration - Alliant Energy, IPL and WPL are subject to regulation for physical and cyber security of their natural gas pipeline systems, and are applying, and monitoring for changes to, these requirements to their pipeline systems.

Department of Homeland Security Transportation Security Administration - Alliant Energy, IPL and WPL are subject to regulation for physical and cybersecurity of their natural gas pipeline systems, and are applying, and monitoring for changes to, these requirements to their pipeline systems.

Environmental - Alliant Energy, IPL and WPL are subject to regulation of environmental matters by federal, state and local authorities as a result of their current and past operations.

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The following are major environmental matters that could potentially have a significant impact on financial condition and results of operations.

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Air Quality -

Climate Change and Greenhouse Gas Regulations - In 2007, the Supreme Court provided direction on the EPA’s authority to regulate GHG and ruled that these emissions are covered by the CAA.

In 2009, the EPA issued a ruling that found GHG emissions contribute to climate change, and therefore, threaten public health and welfare, which was the prerequisite for implementing CO2 reduction standards under the CAA.

In 2009, the EPA issued a ruling that found GHG emissions contribute to climate change and therefore threaten public health and welfare, which is the basis for implementing CO2 reduction standards under the CAA.

While the EPA’s rules to regulate GHG issued under the authority of the CAA remain subject to further review, growing emphasis on climate change and evolving energy technologies are driving efforts to decarbonize the environment through voluntary emissions reductions.

The primary GHG directly emitted from Alliant Energy’s utility operations is CO2 from the combustion of fossil fuels at its EGUs.

Clean Air Act Section 111(d) - In 2015, the EPA issued the Clean Power Plan under Section 111(d) of the CAA to reduce CO2 emissions from existing fossil-fueled EGUs through broad electricity system-wide measures.

This was replaced by the Affordable Clean Energy rule in 2019, to reduce CO2 emissions from existing coal-fueled EGUs through heat rate improvements.

Clean Air Act Section 111(d) - In 2015, the EPA issued the Clean Power Plan rule under Section 111(d) of the CAA to reduce CO2 emissions from existing fossil-fueled EGUs through broad electricity system-wide measures.

This was replaced by the Affordable Clean Energy rule in 2019, to reduce CO2 emissions from existing coal-fired EGUs through heat rate improvements.

In 2021, the U.S.

Court of Appeals for the District of Columbia Circuit vacated and remanded the Affordable Clean Energy rule to the EPA for reconsideration.

In 2022, the Supreme Court issued a ruling limiting the extent of the EPA’s authority under Section 111(d) to emissions reduction technologies and operational improvements.

The EPA is working on a new set of Section 111(d) emission guidelines for states to implement Best System of Emission Reduction standards for GHG emissions from existing fossil-fueled EGUs, and has stated that it intends to issue a proposed rule in 2023 and a final rule in 2024, although a timeline cannot be predicted with certainty.

Court of Appeals for the District of Columbia vacated and remanded the Affordable Clean Energy rule to the EPA for reconsideration.

In 2022, the Supreme Court issued a decision limiting the extent of the EPA’s authority under Section 111(d) to emissions reduction technologies and operational improvements.

In May 2023, the EPA proposed the revised Section 111(d) rule, which would establish emission guidelines for states to implement Best System of Emission Reduction standards for GHG emissions from existing fossil-fueled EGUs and certain combustion turbines.

The proposed requirements would be phased in beginning in 2030.

The EPA also proposed to repeal the Affordable Clean Energy rule.

The EPA’s proposed revised Section 111(d) rule would require states to implement plans to reduce CO2 emissions through various Best System of Emission Reduction standards by applying various measures at affected sources, including retirement, enforceable limits on operational capacity, co-firing with low-GHG fuels, or other technological controls.

State plans must be submitted within 24 months of the final rule’s effective date and are subject to EPA approval.

The proposed standards could impact IPL’s coal-fired Ottumwa Generating Station, George Neal Generating Station, Prairie Creek Generating Station Unit 3 and Louisa Generating Station, and IPL’s natural gas-fired Burlington Generating Station and Prairie Creek Generating Station Unit 4.

In addition, the proposed standards could impact natural gas-fired combustion turbines with a capacity of 300 MW or more, including IPL’s Marshalltown Generating Station and Emery Generating Station, and WPL’s Riverside Energy Center and West Riverside Energy Center.

The proposed standards are currently not expected to impact WPL’s coal-fired Columbia Energy Center or Edgewater Generating Station given current plans to retire these EGUs prior to the proposed 2030 implementation deadline.

The EPA plans to finalize the revised Section 111(d) rule in 2024.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters.

Clean Air Act Section 111(b) - In 2015, the EPA published final standards under Section 111(b) of the CAA, which establish CO2 emissions limits for certain new fossil-fueled EGUs.

Marshalltown and West Riverside are subject to the EPA’s Section 111(b) regulation and have been designed to achieve compliance with these standards.

The EPA is reviewing the Section 111(b) standards, and has stated it intends to issue a proposed rule in 2023 and a final rule in 2024, although a timeline cannot be predicted with certainty.

Litigation related to Section 111(b) is suspended while the EPA revises its Section 111(b) regulations, and Alliant Energy, IPL and WPL are currently unable to predict with certainty the impact of these standards.

In May 2023, the EPA proposed revised standards under Section 111(b), which would establish CO2 emissions limits from certain new and reconstructed fossil-fueled EGUs and would apply prospectively.

IPL’s Marshalltown Generating Station and WPL’s West Riverside Energy Center are currently subject to the EPA’s Section 111(b) regulation and thus would be impacted by these revised standards.

The EPA plans to finalize the revised Section 111(b) rule in 2024.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these standards.

Cross-State Air Pollution Rule - CSAPR is a regional sulfur dioxide and nitrogen oxides cap-and-trade program, where compliance with emission limits may be achieved by purchasing emission allowances and/or reducing emissions through changes in operations or the additions of environmental controls.

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CSAPR establishes state-specific annual sulfur dioxide and nitrogen oxides emission caps and ozone season nitrogen oxides emission caps.

In 2022, the EPA proposed revisions to the CSAPR state-specific ozone season nitrogen oxides emission caps and utility-specific emission allowances for certain states, including Wisconsin, beginning in 2023.

The proposed rule does not apply to Iowa;

however, Iowa could be included in the final rule, which is currently expected in 2023.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters.

In 2023, the EPA finalized revisions to the CSAPR state-specific ozone season nitrogen oxides emission caps and utility-specific emission allowances for certain states, including Wisconsin, beginning in 2023.

WPL currently receives, and expects to receive in the future, enough CSAPR emission allowances to ensure ongoing compliance without the need to purchase additional allowances.

The 2023 CSAPR revisions do not currently apply to Iowa;

however, Iowa

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could be included in a future rule.

As a result, Alliant Energy and IPL are currently unable to predict with certainty the future outcome or impact of these matters.

Water Quality -

Effluent Limitation Guidelines - In 2015, the EPA published final effluent limitation guidelines, which required changes to discharge limits for wastewater from certain IPL and WPL steam EGUs.

Effluent Limitation Guidelines - In 2015, the EPA published final effluent limitation guidelines that required changes to discharge limits for wastewater from certain IPL and WPL steam EGUs.

In 2020, revised effluent limitation guidelines (2020 Reconsideration Rule) became effective, which incorporated flexibility to the 2015 rule, including a new subcategory for coal-fired EGUs that will be retired or converted to no longer burn coal before 2028.

Compliance for existing steam-electric generating facilities is determined by each facility’s wastewater discharge permit and will generally be required by December 31, 2025.

Projects required for compliance are facility-specific.

In 2021, the current Presidential Administration issued an Executive Order requiring the review and possible revision of environmental regulations issued during the prior Administration.

As a result, the EPA expects to undertake a supplemental rule-making to revise the guidelines for steam-electric generating facilities.

As part of the rule-making process, the EPA is expected to determine whether more stringent limitations and standards are appropriate.

The 2020 Reconsideration Rule will remain in effect while the EPA undertakes this new rule-making.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of the anticipated supplemental rule-making.

As a result, in March 2023, the EPA published a proposed supplemental rule (2023 Supplemental Rule) to revise the guidelines for steam-electric generating facilities.

The 2023 Supplemental Rule proposes to tighten some of the flexibility offered in the 2020 Reconsideration Rule for certain waste streams, while additionally proposing a newly defined legacy wastewater waste stream.

The 2020 Reconsideration Rule will remain in effect while the 2023 Supplemental Rule continues through the rule-making process.

Compliance with the 2023 Supplemental Rule will be determined by each facility’s wastewater discharge permit, and new or revised limits would become effective as soon as possible but no later than December 31, 2029.

Alliant Energy, IPL and WPL are currently evaluating the 2023 Supplemental Rule and are unable to predict with certainty future compliance impacts.

Land and Solid Waste -

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IPL and WPL have coal-fired EGUs with coal ash ponds and active CCR landfills that are impacted by this rule.

Compliance obligations associated with the CCR Rule may be subject to change due to future EPA CCR Rule updates, on-going litigation related to the CCR Rule, and any actions taken to-date that may be challenged.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the impact of these updates.

In May 2023, the EPA published proposed amendments to the CCR Rule that would expand the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, including some IPL and WPL facilities.

Alliant Energy, IPL and WPL are currently evaluating the proposed 2023 CCR Rule amendments and are unable to predict with certainty the future outcome or impact of these updates.

Manufactured Gas Plant Sites - Refer to Note 17(e) for discussion of IPL’s and WPL’s MGP sites.

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IPL and WPL currently exceed their respective renewable energy standards requirements.

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3) STRATEGY - Refer to “ Overview ” in MDA for discussion of Alliant Energy’s strategy, which supports its mission to deliver energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and sustainably.

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Refer to the “ Electric Operating Information ” tables for additional details regarding electric utility operations.

Customers - IPL and WPL provide electric utility service to a diversified base of retail customers in several industries, with the largest concentrations in the farming, agriculture, industrial manufacturing, chemical (including ethanol), packaging and food industries.

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IPL and WPL also sell electricity to wholesale customers, which primarily consist of municipalities and rural electric cooperatives.

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Electric Supply - Alliant Energy, IPL and WPL have met, and expect to continue meeting, customer demand of electricity through a mix of electric supply, including owned EGUs, PPAs and additional purchases from wholesale energy markets.

Alliant Energy expects its mix of electric supply to change in the next several years with its planned transition away from coal-fired EGUs by considering additional renewable energy such as solar generation, repowering of existing wind farms and distributed energy resources, including community solar and energy storage systems, natural gas resources, and the actual and potential sale of partial interests in West Riverside to neighboring utilities.

Alliant Energy expects its mix of electric supply to change in the next several years with its planned transition away from coal-fired EGUs by considering additional renewable energy such as solar generation, battery storage, repowering of existing wind farms and distributed energy resources, including community solar and small-scale energy storage systems, dispatchable gas generation projects, and potential sales of partial interests in West Riverside to neighboring utilities.

Long-term generation plans are intended to meet customer demand, reduce air emissions and water impacts, reduce reliance on wholesale market purchases and mitigate the impacts of future EGU retirements while maintaining compliance with long-term electric demand planning reserve margins, renewable energy standards established by regulators and other various requirements.

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IPL and WPL utilize accredited capacity from EGUs they own, and have rights to through PPAs, to meet a substantial portion of their current MISO planning reserve margin requirements and periodically rely on short-term market capacity purchases to supplement the accredited capacity from such EGUs.

Refer to “ Customer Investments ” in MDA for discussion of MISO’s new seasonal resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements effective with the June 1, 2023 through May 31, 2024 MISO Planning Year.

The new seasonal capacity reserve margins are as follows:

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MISO Seasonal Resource Adequacy Process - In 2022, FERC approved MISO’s proposal to change its resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements effective with the June 1, 2023 through May 31, 2024 MISO Planning Year, to help ensure the reliability of electricity in the MISO region.

The process changed from a Summer-based annual construct to four distinct seasons.

FERC’s approval also established planning reserve margin requirements for all market participants on a seasonal basis and determined a seasonal accredited capacity value for certain classes of generating resources, including higher accredited capacity for wind generation during the Spring, Fall and Winter seasons and higher accredited capacity for solar generation during the Summer season.

Alliant Energy, IPL and WPL currently plan to construct and/or acquire additional renewable, battery and natural gas resources to meet the requirements of the seasonal resource adequacy process and have reflected the estimated capital expenditures for these projects in the “Generation” lines in the construction and acquisition table in “ Liquidity and Capital Resources .” Seasonal capacity reserve margins are as follows:

June 2024 - August 2024

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(a) The average cost of natural gas includes commodity and transportation costs, as well as realized gains and losses from swap and option contracts used to hedge the price of natural gas volumes expected to be used by IPL’s and WPL’s natural gas-fired EGUs.

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Natural Gas - Alliant Energy, IPL and WPL own several natural gas-fired EGUs, and WPL also has exclusive rights to the output of AEF’s Sheboygan Falls Energy Facility under an affiliated lease agreement.

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Refer to Note 17(g) for discussion of a court decision, which is currently expected to reduce the base return on equity authorized for MISO transmission owners, including ATC.

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MISO Markets - IPL and WPL are members of MISO, a FERC-approved Regional Transmission Organization, which is responsible for monitoring and ensuring equal access to the transmission system in their footprint.

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The allocated auction revenue rights are used by IPL and WPL to acquire FTRs through the FTR auctions operated by MISO.

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Resource Adequacy - MISO has resource adequacy requirements to help ensure adequate resources to meet forecasted peak load obligations plus a reserve margin.

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In order for an EGU to receive accredited capacity, it must meet MISO capacity accreditation requirements, which can include satisfying transmission requirements identified in its interconnection agreement prior to the MISO planning year.

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Refer to “ Electric Demand Planning Reserve Margin ” above for discussion of MISO’s seasonal resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements.

Electric Operating Information - Alliant Energy 2023 2022 2021

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Wind (b) 4,067 4,422 3,529

Nuclear — — 2,347

Other (b) 1,883 2,803 2,642

Wind (b) 5,410 6,424 5,231

Solar (b) 471 41 17

Coal 6,447 7,416 10,218

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(b) All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with renewable energy standards or other regulatory requirements.

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Electric Operating Information IPL WPL

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Cooling degree days (a):

Cedar Rapids, Iowa (IPL) (normal - 807) 908 974 800 N/A N/A N/A

Madison, Wisconsin (WPL) (normal - 695) N/A N/A N/A 787 845 736

Cedar Rapids, Iowa (IPL) (normal - 819)

974 908 974 N/A N/A N/A

Madison, Wisconsin (WPL) (normal - 706)

N/A N/A N/A 781 787 845

Sources of electric energy (000s MWh):

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Wind (b) 2,504 2,985 2,285 1,563 1,437 1,244

Nuclear — — 2,347 N/A N/A N/A

Other (b) 730 835 1,166 1,153 1,968 1,476

Wind (b) 4,257 4,991 4,088 1,153 1,433 1,143

Solar (b) 11 11 11 460 30 6

Coal 2,252 3,305 4,756 4,195 4,111 5,462

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2) GAS UTILITY OPERATIONS

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The tariffs for IPL’s and WPL’s retail gas customers provide for subsequent adjustments to their rates for the cost of gas sold to these customers.

As a result, natural gas prices do not have a material impact on IPL’s or WPL’s gas margins.

As a result, natural gas prices do not have a material impact on IPL’s or WPL’s operating income.

Gas Demand Planning Reserve Margin - IPL and WPL are required to maintain adequate pipeline capacity to ensure they meet their customers’ maximum daily system demand requirements.

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Cedar Rapids, Iowa (IPL) (normal - 6,699)

5,807 7,222 6,539

Madison, Wisconsin (WPL) (normal - 6,974)

6,157 7,210 6,620

Revenue per Dth sold to retail customers $10.67 $10.69 $8.57

Purchased gas costs per Dth sold to retail customers $6.37 $6.97 $5.29

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Gas Operating Information IPL WPL

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Heating degree days (a):

Cedar Rapids, Iowa (IPL) (normal - 6,697) 7,222 6,539 6,625 N/A N/A N/A

Madison, Wisconsin (WPL) (normal - 6,976) N/A N/A N/A 7,210 6,620 6,789

Cedar Rapids, Iowa (IPL) (normal - 6,699)

5,807 7,222 6,539 N/A N/A N/A

Madison, Wisconsin (WPL) (normal - 6,974)

N/A N/A N/A 6,157 7,210 6,620

Revenue per Dth sold to retail customers $11.80 $11.13 $9.53 $9.54 $10.22 $7.55

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Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 1. Business