ITEM 1. BUSINESS

A. GENERAL

Alliant Energy was incorporated in Wisconsin in 1981 and maintains its principal executive offices in Madison, Wisconsin. Alliant Energy operates as a regulated investor-owned public utility holding company. Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately 1 million electric and approximately 420,000 natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL. The primary first tier wholly-owned subsidiaries of Alliant Energy are: IPL, WPL, Resources and Corporate Services. A brief description of the primary first tier subsidiaries of Alliant Energy is as follows:

1) IPL - was incorporated in 1925 in Iowa as Iowa Railway and Light Corporation. IPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas in select markets in Iowa and southern Minnesota. In Iowa, IPL provides utility services to incorporated communities as directed by the IUB and utilizes non-exclusive franchises, which cover the use of public right-of-ways for utility facilities in incorporated communities for a maximum term of 25 years. At December 31, 2014 , IPL supplied electric and natural gas service to approximately 529,000 and 235,000 retail customers, respectively. IPL is also engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa. In 2014 , 2013 and 2012 , IPL had no single customer for which electric, gas, steam and/or other sales accounted for 10% or more of IPL’s consolidated revenues. Refer to Note 3 for discussion of IPL’s anticipated sales of its Minnesota electric and natural gas distribution assets.

2) WPL - was incorporated in 1917 in Wisconsin as Eastern Wisconsin Electric Company. WPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas in select markets in southern and central Wisconsin. WPL operates in municipalities pursuant to permits of indefinite duration and state statutes authorizing utility operation in areas annexed by a municipality. At December 31, 2014 , WPL supplied electric and natural gas service to approximately 463,000 and 185,000 retail customers, respectively. In 2014 , 2013 and 2012 , WPL had no single customer for which electric, gas and/or other sales accounted for 10% or more of WPL’s consolidated revenues. WPL’s consolidated subsidiary, WPL Transco, holds Alliant Energy’s investment in ATC. Refer to Note 6(a) for further discussion of ATC.

3) RESOURCES - was incorporated in 1988 in Wisconsin. In 2008, Resources was converted to a limited liability company. Alliant Energy’s non-regulated investments are organized under Resources. Refer to “ Information Relating to Non-regulated Operations ” for additional details.

4) CORPORATE SERVICES - was incorporated in 1997 in Iowa. Corporate Services provides administrative services to Alliant Energy, IPL, WPL and Resources.

Refer to Note 17 for further discussion of business segments, which information is incorporated herein by reference.

At December 31, 2014 , Alliant Energy employees covered by collective bargaining agreements were as follows:

2) CAPITAL EXPENDITURE AND INVESTMENT PLANS - Refer to “ Liquidity and Capital Resources ” in MDA for discussion of anticipated construction and acquisition expenditures for 2015 through 2018 .

3) REGULATION - Alliant Energy, IPL and WPL are subject to regulation by various federal, state and local agencies. The following includes the primary regulations impacting Alliant Energy’s, IPL’s and WPL’s businesses.

FERC -

Public Utility Holding Company Act of 2005 - Alliant Energy is registered with FERC as a public utility holding company, pursuant to the Public Utility Holding Company Act of 2005, and is required to maintain certain records and to report certain transactions involving its public utilities, service company and other entities regulated by FERC. 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.

Energy Policy Act - The Energy Policy Act 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. 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.

Federal Power Act - FERC also has jurisdiction, under the Federal Power Act, over certain electric utility facilities and operations, electric wholesale and transmission rates, dividend payments, issuance of IPL’s securities, and accounting practices of Corporate Services, IPL and WPL.

Electric Wholesale Rates - IPL and WPL have received wholesale electric market-based rate authority from FERC. Market-based rate authorization allows for wholesale sales of electricity within the MISO and PJM markets and in transactions directly with third parties, based on the market value of the transactions. IPL and WPL also have FERC-approved cost-of-service based rates related to the provision of firm full- and partial-requirement wholesale electric sales. Both IPL’s and WPL’s wholesale cost-of-service tariffs are formula-based tariffs that allow for true-ups to actual costs, including fuel costs.

Electric Transmission Rates - FERC regulates the rates charged for electric transmission facilities used in interstate commerce. Neither IPL nor WPL own or operate electric transmission facilities; however, both IPL and WPL pay for the use of the interstate electric transmission system based upon FERC-regulated rates. IPL and WPL rely primarily on the use of the ITC and ATC transmission systems, respectively. Due to the formula rates used by ITC and ATC to charge their customers and possible future changes to these rates, there is uncertainty regarding IPL’s and WPL’s future electric transmission service expense. Refer to “ Other Future Considerations ” in MDA for further discussion of electric transmission service expense.

Natural Gas Act - FERC regulates the transportation and sale for resale of natural gas in interstate commerce under the Natural Gas Act. Under the Natural Gas Act, FERC has authority over certain natural gas facilities and operations of IPL and WPL.

IUB - IPL is subject to regulation by the IUB related to its operations in Iowa for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, sales of assets with values that exceed 3% of IPL’s revenues for its Iowa jurisdiction, and approval of the location and construction of EGUs.

Retail Utility Base Rates - IPL files periodic requests with the IUB for retail rate changes. These filings are based on historical test periods. 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. Interim retail rates can be placed in effect 10 days after the rate application filing, subject to refund, and must be based on past precedent. The IUB must decide on requests for retail rate changes within 10 months of the date of the application for which changes are filed, or the interim rates granted become permanent.

Retail Commodity Cost Recovery Mechanisms - IPL’s retail electric and natural gas tariffs contain automatic adjustment clauses for changes in prudently incurred commodity costs required to serve its retail customers in Iowa. Any over- or under-collection of commodity costs for each given month are automatically reflected in future billings to retail customers.

Retail Electric Transmission Cost Recovery Mechanism - Electric transmission service expense is billed to IPL’s Iowa retail electric customers through a transmission cost rider. This cost recovery mechanism provides for subsequent adjustments to electric rates charged to Iowa retail electric customers for changes in electric transmission service expense. Changes in the under-/over-collection of these costs are reflected in future billings to customers. The transmission cost rider will remain in effect until the IUB’s final decision in IPL’s next retail electric base rate case, at which time the rider will continue in its current form, continue in a modified form or be terminated.

Energy Efficiency Cost Recovery Mechanism - In accordance with Iowa law, IPL is required to file an EEP every five years with the IUB. An EEP provides a utility’s plan and related budget to achieve specified levels of energy savings. IUB approval demonstrates that the IUB believes that IPL’s EEP is reasonably expected to achieve cost-effective delivery of the energy efficiency programs. To the extent approved by the IUB, costs associated with executing the EEP are recovered from ratepayers through an additional tariff called an EECR factor. The EECR factors are revised annually and include a reconciliation to eliminate any over- or under-recovery of energy efficiency expense from prior periods.

Electric Generating Units - IPL must obtain a certificate of public convenience, use and necessity (GCU Certificate) from the IUB in order to construct a new, or significantly alter an existing, EGU located in Iowa with 25 MW or more of capacity. IPL’s ownership and operation of EGUs (including those located outside the state of Iowa) to serve Iowa customers is subject to retail utility rate regulation by the IUB.

Gas Distribution Projects - IPL must obtain a pipeline permit from the IUB related to the citing of certain utility gas pipelines in Iowa.

Advance Rate-making Principles - Iowa law provides Iowa utilities with rate-making principles prior to making certain generation investments in Iowa. As a result, IPL may file for, and the IUB must render a decision on, rate-making principles for EGUs located in Iowa, including new base-load (nuclear or coal-fired generation) EGUs with a nameplate generating capacity of 300 MW or more, combined-cycle natural gas-fired EGUs and renewable generating resources, such as wind facilities. Upon approval of rate-making principles by the IUB, IPL must either build the EGU under the approved rate-making principles, or not at all.

Electric Generating Unit Emission Controls Projects - IPL is required to submit an EPB 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. IPL must simultaneously submit this plan and budget to the Iowa DNR for a determination of whether the plan and budget meet state environmental requirements for regulated emissions. The reasonable costs associated with implementing the approved plan are expected to be included in IPL’s future retail electric rates.

PSCW - Alliant Energy is subject to regulation by the PSCW for the type and amount of Alliant Energy’s investments in non-utility businesses and other affiliated interest activities, among other matters. WPL is also subject to regulation by the PSCW related to its operations in Wisconsin for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, issuance and use of proceeds of securities, affiliate transactions, approval of the location and construction of EGUs and certain other additions and extensions to facilities.

Retail Utility Base Rates - WPL files periodic requests with the PSCW for retail rate changes. These filings are required to be based on forward-looking test periods. There is no statutory time limit for the PSCW to decide retail base rate requests. However, the PSCW attempts to process retail base rate cases in approximately 10 months and has the ability to approve interim retail rate relief, subject to refund, if necessary. Currently, WPL is required to defer a portion of its earnings if its annual regulatory return on common equity exceeds certain levels and is allowed to request a change in retail base rates if its annual return on common equity falls below a certain level.

Retail Commodity Cost Recovery Mechanisms -

Electric - WPL’s retail electric base rates include estimates of annual fuel-related costs anticipated during the test period. During each retail electric rate proceeding, or in a separate fuel cost plan approval proceeding, the PSCW sets fuel monitoring ranges based on the forecasted fuel-related costs used to determine rates in such proceeding. If WPL’s actual fuel-related costs fall outside these fuel monitoring ranges, WPL is authorized to defer the incremental over- or under-collection of fuel-related costs from retail electric customers that are outside the approved ranges. Deferrals of under-collections are reduced to the extent actual return on common equity earned by WPL during the fuel cost plan year exceeds the applicable authorized return on common equity. Subject to review and approval by the PSCW, any deferred over- or under-collection of fuel-related costs for each year are reflected in future billings to retail customers.

Natural Gas - WPL’s retail natural gas tariffs contain an automatic adjustment clause for changes in prudently incurred natural gas costs required to serve its retail gas customers. Any over- or under-collection of natural gas costs for each given month are automatically reflected in future billings to retail customers.

Retail Electric Transmission Cost Recovery - WPL’s retail electric base rates include estimates of electric transmission service expense anticipated during the forward-looking test period. A majority of WPL’s electric transmission service expense in 2015 and 2016 will be subject to a reconciliation of such estimated amounts to actual costs incurred with any difference deferred for inclusion in future base rate changes.

Energy Efficiency Cost Recovery - WPL contributes a certain percentage of its annual utility revenues to help fund Focus on Energy, Wisconsin’s state-wide energy efficiency and renewable energy resource program. Estimated contributions to Focus on Energy, along with WPL-run energy efficiency program costs, are recovered from WPL’s retail customers through changes in base rates determined during periodic rate proceedings and include a reconciliation of such estimated amounts to actual costs incurred with any difference deferred for inclusion in a future base rate proceeding.

New Electric Generating Units - A CA application is required to be filed with the PSCW for construction approval of any new EGU with a capacity of less than 100 MW and a project cost of $10 million or more. WPL must obtain a CPCN from the PSCW in order to construct a new EGU in Wisconsin with a capacity of 100 MW or more. In addition, WPL’s ownership and operation of EGUs (including those located outside the state of Wisconsin) to serve Wisconsin customers is subject to retail utility rate regulation by the PSCW.

Electric Generating Unit Upgrades - A CA application is required to be filed with the PSCW for construction approval of any additions to EGUs, including emission controls projects. The current PSCW rules require a CA application for such projects with an estimated project cost of $10 million or more.

Gas Distribution Projects - A CA application is required to be filed with the PSCW for construction approval of gas projects with an estimated project cost of $2.5 million or more and at any time that WPL requests to extend gas service to a new portion of its service territory.

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 nuclear or fossil-fueled EGU or renewable generating resource, such as a wind facility, utilized to serve Wisconsin customers. WPL is not obligated to file 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.

MPUC - IPL is subject to regulation by the MPUC related to its operations in Minnesota for various matters including, but not limited to, retail utility rates and standards of service, accounting requirements, affiliate transactions, and approval of the location and construction of EGUs located in Minnesota with a capacity in excess of 50 MW.

Retail Utility Rates - Requests for retail rate change can be based on either historical or projected data and interim retail rates can be implemented 60 days after the filing date, with regulatory review. IPL has historically requested retail rate relief based on historical test periods. The historical test periods may be adjusted for certain known and measurable capital additions placed in service by IPL and operating and maintenance expenses incurred by IPL within 12 months after the end of the test year. Unless otherwise ordered, the MPUC must reach a final decision within 10 months of filing for retail rate relief; however, the MPUC can extend the timing by 90 days.

Renewable Energy Cost Recovery Mechanism - In 2011, IPL received an order from the MPUC approving the implementation of an automatic cost recovery rider on a temporary basis to recover costs associated with renewable generation. The renewable energy rider does not require a base rate case for annual revision of rates charged to IPL’s Minnesota retail electric customers, but requires that the renewable energy costs incurred be fully reconciled against the revenues collected for such costs. IPL currently utilizes this mechanism to recover costs associated with its Whispering Willow - East wind project located in Iowa and production tax credits.

Refer to Note 3 for discussion of IPL’s anticipated sales of its Minnesota electric and natural gas distribution assets.

Environmental - Extensive environmental laws and regulations are applicable as a result of current and past operations. The environmental laws and regulations relate to the protection of the environment and health and safety matters, including those governing air emissions; water discharges; the management, storage and disposal of hazardous materials; and the clean-up of contaminated sites, including former MGP sites.

The EPA administers certain federal regulatory programs and has delegated the administration of other environmental regulatory programs to the applicable state environmental agencies. In general, the state agencies have jurisdiction over air and water quality, hazardous substances management, transportation and clean-up, and solid waste management requirements. In certain cases, the state environmental agencies have delegated the administration of environmental programs to local agencies.

Federal, state and local permits are regularly obtained to assure compliance with environmental laws and regulations. Costs associated with such compliance have increased in recent years and are expected to continue to increase in the future. Prudently incurred compliance and remediation costs for IPL and WPL are anticipated to be recoverable, in whole or part, through future rate case proceedings. Refer to “ Environmental Matters ” in MDA and Note 16(e) for further discussion of electric and gas environmental matters, including current or proposed environmental regulations. Refer to “ Strategic Overview - Environmental Compliance Plans” in MDA for details of future environmental compliance plans to adhere to applicable environmental requirements.

Refer to Notes 1(b) , 1(g) , 2 and 16(e) and “ Rate Matters ” and “ Environmental Matters ” in MDA for additional information regarding regulation and utility rate matters.

4) STRATEGIC OVERVIEW - Refer to “ Strategic Overview ” in MDA for discussion of various strategic actions by Alliant Energy, IPL and WPL.

1) ELECTRIC UTILITY OPERATIONS

General - Electric utility operations represent the largest operating segment for Alliant Energy, IPL and WPL. Alliant Energy’s electric utility operations are located in the Midwest with IPL providing electric service in Iowa and southern Minnesota and WPL providing electric service in southern and central Wisconsin. In September 2013, IPL signed a definitive agreement to sell its Minnesota electric distribution assets. Refer to Note 3 for discussion of this anticipated sale. Refer to the “ Electric Operating Information ” tables for additional details regarding electric utility operations.

Jurisdictions - Electric utility revenues by state were as follows (dollars in millions):

The percentage of regulated electric utility revenues were as follows:

Customers - The number of electric customers and communities served at December 31, 2014 was as follows:

IPL and WPL provide electric utility service to a diversified base of retail customers in several industries, with the largest concentrations in the food manufacturing, chemical (including ethanol) and paper industries. IPL’s retail customers in the above table are billed under base rates established by the IUB or MPUC that include recovery of and a return on investments in electric infrastructure and recovery of purchased electric capacity costs and other costs required to serve customers. Electric transmission service expense is billed to IPL’s Iowa retail electric customers through a transmission cost rider. This cost recovery mechanism provides for subsequent adjustments to electric rates charged to Iowa electric retail customers for changes in electric transmission service expense. IPL’s fuel-related costs are recovered pursuant to fuel adjustment clauses. WPL’s retail customers in the above table are billed under base rates established by the PSCW that include recovery of and a return on investments in electric infrastructure and recovery of fuel-related costs, purchased electric capacity costs, electric transmission service costs and other costs required to serve customers. WPL defers fuel-related costs that exceed or fall below established fuel monitoring ranges through an electric fuel cost recovery mechanism. Deferrals of under-collections are reduced to the extent actual return on common equity earned by WPL during the fuel cost plan year exceeds the applicable authorized return on common equity. Refer to “ Rate Matters ” in MDA for details of IPL’s settlement agreement approved by the IUB in September 2014 and WPL’s retail electric and gas base rate case approved by the PSCW in July 2014. Refer to Note 2 for additional discussion of utility rate cases.

Wholesale customers in the above table, which primarily consist of municipalities and rural electric cooperatives, are billed under wholesale service agreements. These agreements include standardized pricing mechanisms that are detailed in tariffs approved by FERC through wholesale rate case proceedings. The tariffs include an annual true-up process for actual costs incurred. A majority of IPL’s and WPL’s wholesale service agreements have terms that end after 2016. Refer to “ Other Future Considerations ” in MDA for discussion of notifications provided to each of IPL and WPL to terminate certain of their wholesale power supply agreements. Refer to Note 3 for discussion of IPL’s Minnesota electric distribution asset sales agreement, which includes a wholesale power supply agreement that is subject to FERC approval.

In addition, WPL has bulk power customers, included in “Other customers” in the above table, that are billed according to negotiated, long-term customer-specific contracts, pursuant to FERC-approved tariffs.

Seasonality - Electric sales are seasonal to some extent with the annual peak normally occurring in the summer months due to air conditioning requirements. Electric sales are also impacted to a certain extent in the winter months due to heating requirements. In 2014 , the maximum peak hour demands were as follows:

Competition - Retail electric customers in Iowa, Wisconsin and Minnesota currently do not have the ability to choose their electric supplier, and IPL and WPL have obligations to serve all their retail electric customers. Although electric service in Iowa, Wisconsin and Minnesota is regulated, IPL and WPL still face competition from self-generation by large industrial customers, customer- and third party-owned generation (e.g. rooftop solar panels), alternative energy sources, and petitions to municipalize (Iowa) as well as service territory expansions by municipal utilities through annexations (Wisconsin). However, IPL and WPL attempt to attract new customers into their service territories in an effort to keep energy rates low for all its customers.

Renewable Energy Standards - As discussed in greater detail below, the states in which IPL and WPL operate have RES, which establish the amount of energy electric utilities or service providers must supply from renewable resources.

IPL - IPL has requirements to comply with RES in both Iowa and Minnesota and primarily relies upon RECs generated from the wind projects it owns and renewable energy acquired under PPAs to meet such requirements. IPL allocates its portfolio of RECs between its Iowa and Minnesota jurisdictions based on a load-ratio share. IPL has excess RECs in Iowa and a shortfall of RECs in Minnesota. However, the excess RECs in Iowa are much larger than the Minnesota shortfall partially due to the relatively small amount of IPL’s load served in Minnesota compared to Iowa. IPL is permitted to use its surplus of RECs in Iowa to meet its deficit of RECs in Minnesota. IPL expects to meet both its Iowa and Minnesota renewable energy requirements on a system-wide basis without the need to purchase additional RECs.

Iowa - IPL is required to purchase or own 49.8 MW of nameplate capacity from alternate energy or small hydro facilities located in its service area. IPL currently exceeds this Iowa requirement.

Minnesota - IPL’s total Minnesota retail electric sales supplied with renewable energy sources must be at least 12% currently and 17% by 2016, 20% by 2020, and 25% by 2025. Utilities in Minnesota may meet the requirements of the RES with renewable energy generated by the utility, renewable energy acquired under PPAs, or the use of accumulated or acquired RECs. IPL has met the 12% requirement and currently expects to satisfy future Minnesota RES requirements with its current wind generation and wind PPAs, supplemented as needed by acquiring additional RECs from its anticipated Iowa excess supply.

In addition to the above Minnesota requirement, IPL’s total Minnesota retail electric sales supplied with solar power must be at least 1.5% by 2020. IPL currently estimates that approximately 10 MW of solar power would be needed for compliance with this requirement by 2020.

WPL - The Wisconsin RES requires WPL to increase the portion of its total Wisconsin retail electric sales supplied by renewable energy sources above a benchmark of average retail sales from renewables in 2001, 2002 and 2003. The RES required a 2% increase above the benchmark by 2010 and will require a 6% increase above the benchmark by 2015. Based on this RES, WPL was required to supply a minimum of 5.28% of its total Wisconsin retail electric sales with renewable energy sources by 2010 and will be required to increase this amount to 9.28% by 2015. WPL may reach the RES with renewable energy it generates, it acquires under PPAs or through the use of renewable resource credits. WPL has met the 2010 requirements of this RES and currently expects to meet the 2015 requirements of the RES with its current renewable portfolio, which primarily consists of wind and hydro.

Energy Efficiency - IPL and WPL continue to promote energy efficiency, including their customers’ ability to efficiently manage their energy use. Refer to “ Strategic Overview ” in MDA for discussion of energy efficiency programs at IPL and WPL.

Electric Supply - Alliant Energy, IPL and WPL have met historical customer demand of electricity and expect to continue meeting future demand through a mix of electric supply including internally generated electricity, PPAs and additional

purchases from wholesale energy markets. Alliant Energy’s mix of electric supply has changed with WPL’s purchases of Wisconsin Electric Power Company’s 25% interest in Edgewater Unit 5 in 2011 and Riverside in 2012, the completion of wind projects including WPL’s Bent Tree wind project in 2011, the expiration of WPL’s Kewaunee PPA in December 2013, IPL’s DAEC PPA for a term from February 22, 2014 through December 31, 2025, WPL’s 150 MW PPA for a term from January 1, 2014 through December 31, 2018 and IPL’s retirement of various EGUs. Alliant Energy expects its mix of electric supply to change further in the next several years with IPL’s construction of Marshalltown, WPL’s proposed construction of the Riverside expansion and the proposed retirement of additional EGUs. Generation plans are periodically updated to identify longer term electric supply resource needs. These long-term generation plans are intended to meet customer demand, reduce reliance on PPAs and wholesale market purchases and mitigate the impacts of future EGU retirements while maintaining compliance with long-term electric demand planning reserve margins, environmental requirements and RES established by regulators. Alliant Energy, IPL and WPL currently expect to meet utility customer demand in the future. However, unanticipated regional or local reliability issues could still arise in the event of unexpected delays in the construction of new generating and/or transmission facilities, retirement of EGUs, EGU outages, transmission system outages or extended periods of extreme weather conditions. Refer to the “ Electric Operating Information ” tables for a profile of the sources of electric supply used to meet customer demand from 2010 to 2014 . Refer to “ Strategic Overview ” in MDA for details of future generation plans.

Electric Demand Planning Reserve Margin - IPL and WPL are required to maintain a planning reserve margin above their load at the time of the MISO-wide peak to ensure reliability of electric service to their customers. The required installed capacity reserve margin is 14.3% and the required unforced capacity reserve margin is 7.1% for the June 1, 2015 through May 31, 2016 MISO planning year. IPL and WPL currently have adequate capacity to meet the MISO planning reserve margin requirements for the June 1, 2015 through May 31, 2016 MISO planning year.

Generation - IPL and WPL own a portfolio of EGUs located in Iowa, Wisconsin and Minnesota with a diversified fuel mix including coal, natural gas and renewable resources. Refer to “ Properties ” in Item 2 for details of IPL’s and WPL’s EGUs.

Nameplate Capacity - The nameplate capacity of IPL’s and WPL’s EGUs by primary fuel type is as follows:

Fuel Costs - The average cost of delivered fuel per million British Thermal Units used for electric generation was as follows:

Coal - Coal is a primary fuel source for internally generated electric supply and represented approximately 45%, 43% and 47% of Alliant Energy’s, IPL’s and WPL’s total sources of electric energy in 2014 , respectively. Alliant Energy, through Corporate Services as agent for IPL and WPL, has entered into contracts with different suppliers to help ensure that a specified supply of coal is available at known prices for IPL’s and WPL’s coal-fired EGUs for 2015 through 2018 . As of December 31, 2014 , existing contracts provide for a portfolio of coal supplies that cover approximately 72%, 65%, 31% and 21% of IPL’s and WPL’s estimated aggregate annual coal supply needs for 2015 through 2018 , respectively. Alliant Energy, IPL and WPL believe this portfolio of coal supplies represents a reasonable balance between the risks of insufficient supplies and those associated with being unable to respond to future coal market changes. Remaining coal requirements are expected to be met from either future term contracts or purchases in the spot market. Alliant Energy, through its subsidiaries Corporate

Services, IPL and WPL, also enters into various coal transportation agreements to meet IPL’s and WPL’s coal supply requirements. As of December 31, 2014 , existing coal transportation agreements cover approximately 100% and 84% of IPL’s estimated coal transportation needs for 2015 and 2016 , respectively, and 100% and 63% of WPL’s estimated coal transportation needs for 2015 and 2016 , respectively.

Nearly all of the coal utilized by IPL and WPL is from the Wyoming Powder River Basin. A majority of this coal is transported by rail-car directly from Wyoming to IPL’s and WPL’s EGUs, with the remainder transported from Wyoming to the Mississippi River by rail-car and then via barges to the final destination. As protection against interruptions in coal deliveries, IPL and WPL strive to maintain average coal inventory supply targets of 25 to 55 days for EGUs with year-round deliveries and 30 to 150 days (depending upon the time of year) for EGUs with seasonal deliveries. As of December 31, 2014 , actual inventory days ranged from 23 to 57 days for EGUs with year-round deliveries and 72 to 80 days for EGUs with seasonal deliveries. The days on hand were computed based on actual tons of inventory divided by estimated average daily tons burned. During 2014, coal deliveries to one of WPL’s EGUs were delayed due to additional rail-car traffic for non-coal commodities. As a result, WPL shifted some of its rail-car coal traffic to a less congested route to help avoid such delays. Coal is periodically tested from sources other than the Wyoming Powder River Basin to determine which alternative sources of coal are most compatible with EGUs. Access to alternative sources of coal is expected to provide further protection against interruptions and lessen dependence on the primary coal source.

Average delivered fossil fuel costs are expected to increase in the future due to price structures and adjustment provisions in existing coal contracts, rate structures and adjustment provisions in existing transportation contracts, expiration of legacy transportation contracts, fuel-related surcharges incorporated by transportation carriers and expected future coal and transportation market trends. Legacy transportation contracts at each of IPL and WPL expired at the end of 2014, which will result in higher coal transportation costs for IPL and WPL beginning in 2015. Existing coal commodity contracts with terms of greater than one year have fixed future year prices that generally reflect recent market trends. Rate adjustment provisions in older transportation contracts are primarily based on changes in the Rail Cost Adjustment Factor as published by the U.S. Surface Transportation Board. Rate adjustment provisions in more recent transportation contracts are based on changes in the All Inclusive Index Less Fuel as published by the Association of American Railroads. These more recent transportation contracts also contain fuel surcharges that are subject to change monthly based on changes in diesel fuel prices. Other factors that may impact coal prices for future commitments are increasing costs for supplier mineral rights, increasing costs to mine the coal, and changes in various associated laws and regulations. For example, emission restrictions related to SO2, NOx and mercury, along with other environmental limitations on EGUs, continue to increase and will likely limit the ability to obtain, and further increase the cost of, adequate coal supplies. Factors that may impact future transportation rates include, but are not limited to: the need for railroads to enhance and expand infrastructure, corresponding investments in locomotives and crews, and the desire to improve margins on coal movements commensurate with margins on non-coal movements.

Alliant Energy, IPL and WPL believe they are reasonably insulated against coal price volatility given their current coal procurement process, the specific coal market in their primary purchase region and regulatory cost-recovery mechanisms. The coal procurement process stresses periodic purchases, staggering of contract terms, stair-stepped levels of supply going forward for multiple years and supplier diversity. Similarly, given the term lengths of their transportation agreements and strategic alignment of agreement expirations for negotiation purposes, Alliant Energy, IPL and WPL believe they are reasonably insulated against future higher coal transportation rates from the major railroads.

Natural Gas - Alliant Energy owns several larger natural gas-fired EGUs, including IPL’s Emery ( 603 MW), WPL’s Riverside ( 675 MW), WPL’s Neenah ( 371 MW) and Resources’ Sheboygan Falls ( 347 MW) facilities. WPL has exclusive rights to the output of Sheboygan Falls under an affiliated lease agreement. IPL and WPL also currently own several smaller natural gas-fired EGUs and IPL currently expects to convert an EGU currently fueled with coal to natural gas in the future. These facilities help meet customer demand for electricity generally during peak hour demands and when natural gas prices are low enough to make natural gas-fired generation economical compared to other fuel sources. Internally generated electric supply from natural gas-fired EGUs represented approximately 10%, 6% and 13% of Alliant Energy’s, IPL’s and WPL’s total sources of electric energy in 2014 , respectively. Alliant Energy manages the gas supply to these gas-fired EGUs and provides supply through a combination of third-party deliveries and pipeline transportation and storage contracts held by IPL and WPL.

Refer to “ Strategic Overview ” for discussion of IPL’s construction of Marshalltown, an approximate 650 MW natural gas-fired combined-cycle EGU and WPL’s proposed construction of the Riverside expansion, an approximate 650 MW natural gas-fired combined-cycle EGU.

Wind - IPL’s 200 MW Whispering Willow - East wind project in Franklin County, Iowa began generating electricity in 2009. WPL’s 68 MW Cedar Ridge wind project in Fond du Lac County, Wisconsin began generating electricity in 2008. WPL’s

201 MW Bent Tree wind project in Freeborn County, Minnesota began full generation of electricity in 2011. Internally generated electric supply from these three wind facilities represented approximately 5%, 4% and 5% of Alliant Energy’s, IPL’s and WPL’s total sources of electric energy in 2014 , respectively. All or some of the renewable energy attributes associated with generation from these sources may be used in future years to comply with RES or other regulatory requirements, or sold to third parties in the form of RECs or other environmental commodities. Refer to “ Properties ” in Item 2 for the generating capacity of these wind projects.

Purchased Power - IPL and WPL periodically enter into PPAs and purchase electricity from wholesale energy markets to meet a portion of their customer demand for electricity. Purchased power represented approximately 40%, 47% and 33% of Alliant Energy’s, IPL’s and WPL’s total sources of electric energy in 2014 , respectively. IPL’s most significant PPA is for the purchase of up to 431 MWs of capacity and the resulting energy from DAEC for a term from February 22, 2014 through December 31, 2025. WPL’s most significant PPA is for the purchase of 150 MWs of energy for a term from January 1, 2014 through December 31, 2018.

Refer to Note 1(g) for discussion of IPL’s and WPL’s rate recovery of fuel-related costs and Note 16(b) for details on IPL’s and WPL’s coal, natural gas and other purchased power commitments.

Electric Transmission - IPL and WPL do not own electric transmission assets and currently receive substantially all their electric transmission services from ITC and ATC, respectively. ITC and ATC are independent for-profit, transmission-only companies and are transmission-owning members of the MISO Regional Transmission Organization, Midwest Reliability Organization and Reliability First Corporation Regional Entities. The annual transmission service rates that ITC and ATC charge their customers are calculated each calendar year using a FERC-approved cost of service formula rate template referred to as Attachment “O.” Refer to “ Other Future Considerations ” in MDA for additional information regarding transmission service charges from ITC and ATC, and discussion of potential changes to ATC’s return on equity and regulatory capital structure for common equity, which could result in Alliant Energy and WPL realizing lower equity income and dividends from ATC in the future. Refer to Note 1(g) for discussion of a transmission cost rider utilized by IPL for recovery of its electric transmission service expense, and discussion of WPL’s electric transmission service expense, which is recovered from its retail electric customers through changes in base rates determined during periodic rate proceedings. Note 1(g) also discusses escrow accounting treatment for electric transmission service expense, which WPL received as part of its approved retail electric rate case (2015/2016 Test Period) in July 2014 from the PSCW. Refer to Note 18 for details of agreements between ATC and WPL.

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 service territories. IPL and WPL participate in the wholesale energy and ancillary services markets operated by MISO, which are discussed in more detail below. Corporate Services acts as agent on behalf of IPL and WPL pursuant to service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within the markets operated by MISO and PJM. Corporate Services assigns such sales and purchases between IPL and WPL based on statements received from MISO and PJM. Refer to Note 18 for additional discussion of these assigned amounts.

Wholesale Energy Market - IPL and WPL participate in the wholesale energy market operated by MISO. The market dictates the process by which IPL and WPL buy and sell wholesale electricity, obtain transmission services, schedule generation and ensure resource adequacy to reliably serve load. In the market, IPL and WPL submit day-ahead and/or real-time bids and offers for energy. MISO evaluates IPL’s, WPL’s and other market participants’ offers, bids and energy injections into, and withdrawals from, the system to economically dispatch the entire MISO system on an hourly basis. MISO settles these hourly offers and bids based on locational marginal prices, which are market-driven values based on the specific time and location of the purchase and/or sale of energy. The market is intended to send price signals to stakeholders about where generation or transmission system expansion is needed. In addition, MISO may dispatch generators that support reliability needs, but that would not have operated based on economic needs. In these cases, MISO’s settlement assures that these generators are made whole financially for their variable costs. IPL and WPL may also periodically engage in related transactions in PJM’s bid/offer-based wholesale energy market, which are accounted for in a similar manner as the MISO transactions.

Ancillary Services Market - IPL and WPL also participate in MISO’s ancillary services market. The ancillary services market integrates the procurement and use of regulation and contingency reserves with the existing wholesale energy market. Regulation reserves refer to generation available to meet the moment-to-moment changes in generation that are necessary to meet changes in electricity demand. Contingency reserves refer to additional generation or demand response resources, either on-line or that can be brought on-line within 10 minutes, to meet certain major events such as the loss of a large EGU or transmission line.

Financial Transmission Rights and Auction Revenue Rights - In areas of constrained transmission capacity, costs could be higher due to congestion and its impact on locational marginal prices. FTRs provide a hedge for congestion costs that occur in the MISO day-ahead energy market. MISO allocates ARRs to IPL and WPL each year based on historical use of the transmission system. The revenue rights associated with the allocated ARRs are used by IPL and WPL to acquire FTRs through the FTR auctions operated by MISO. MISO allocates ARRs annually based on a fiscal year from June 1 through May 31. IPL’s and WPL’s current FTRs acquired from ARRs extend through May 31, 2015 .

Multi-value Projects - The MISO tariff identifies costs billed to IPL and WPL, including costs related to various shared transmission projects, including MVPs. MVPs include new large scale transmission projects that enable the reliable and economic delivery of energy in support of documented energy policy mandates or provide economic value across multiple pricing zones within MISO. MVP costs are socialized across the entire MISO footprint based on energy usage of each MISO participant. MISO tariff costs billed to IPL and WPL also include costs related to other shared transmission projects, including projects designed to reduce market congestion, to provide interconnection to the transmission grid for new generation, and to ensure compliance with applicable reliability standards. The costs of these projects are primarily allocated to MISO participants in a way that is commensurate with the benefit to the participants’ pricing zone. The MISO transmission charges billed to IPL and WPL are expected to increase in the future due to the increased number of shared transmission projects occurring in the MISO region. Refer to “ Other Future Considerations ” in MDA for further discussion of MISO transmission charges billed to IPL and WPL.

Resource Adequacy - MISO conducts various studies regarding reliability of electric service to ensure its market participants have adequate resources, either owned or contracted, to meet MISO’s forecasted peak load obligations plus a reserve margin. Only accredited capacity assigned to EGUs from the MISO resource adequacy process is available to meet these requirements. To connect to the transmission system, MISO requires an EGU to obtain an interconnection agreement. In order for an EGU to receive accredited capacity, it must, among other requirements, satisfy all transmission requirements identified in its interconnection agreement prior to the MISO planning year. New EGUs like Marshalltown may not initially receive accredited capacity based on the inability to satisfy all identified transmission requirements. Therefore, accredited capacity may not be granted to such EGUs until all identified transmission requirements are resolved. As members of MISO, IPL and WPL must adhere to these resource adequacy protocols in executing their generation resource plans.

Attachment Y Notices and System Support Resources - MISO requires its market participants (including IPL and WPL, among others) who own EGUs to submit an Attachment Y Notice if they plan to retire an EGU, reduce the capacity of an EGU or suspend all or a portion of the operations of an EGU for a period longer than two months. Upon receiving an Attachment Y Notice, MISO will conduct a study to determine whether all or a portion of the EGU’s capacity is necessary to maintain system reliability. If the EGU’s capacity is determined to be necessary to maintain system reliability, MISO designates the EGU as an SSR. When an EGU is required to continue to operate for system reliability, the market participant may enter into an SSR agreement and negotiate an annual revenue requirement with MISO. The annual revenue requirement for the SSR is subject to FERC approval and is assigned to load serving entities that benefit from the continued operations of the EGU. In 2013, the PSCW issued an order allowing investor-owned Wisconsin utilities to defer SSR costs incurred through December 31, 2015. Alliant Energy, IPL and WPL are currently unable to estimate the amount of aggregate SSR charges that may be assigned to IPL and WPL as load serving entities. Alliant Energy, IPL and WPL are also currently unable to estimate the impacts of any potential SSR designations on EGUs they plan to retire or modify. Refer to “ Strategic Overview ” in MDA for discussion of EGUs that IPL and WPL currently plan to retire or modify, such as changing from coal-fired to an alternative fuel source, in the next few years.

FERC Order 1000 - In 2011, FERC issued Order 1000, which reforms its electric transmission planning and cost allocation requirements for public utility transmission providers. One substantial change from the order is the requirement for projects with regional cost allocation to have the federal right of first refusal removed. Incumbent public utility transmission providers, including ITC and ATC, no longer have a federal right of first refusal to build, own and operate large-scale transmission projects located within their service territory that have regional cost sharing. To comply with this requirement, MISO is creating a competitive bidding process for projects subject to the right of first refusal removal, which could lead to a potential decrease in the expected costs of impacted future transmission projects. In January 2015, FERC issued an order that denied rehearing requests and accepted MISO’s revised Order 1000 compliance filing, subject to a further compliance filing for certain changes related to definitions of projects retaining a federal right of first refusal and requirements for qualified transmission developers. Alliant Energy, IPL and WPL are currently unable to determine what impacts, if any, this order may have on their future electric transmission service charges.

Electric Environmental Matters - Refer to Note 16(e) and “ Environmental Matters ” in MDA for discussion of electric environmental matters, including current or proposed environmental regulations.