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Property, Plant and Equipment | 12 Months Ended
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Dec. 31, 2017
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2017 |  | 2016 |  | 2017 |  | 2016
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service |  | $6,655.3 |  |  |  | $5,866.9 |  |  |  | $3,715.9 |  |  |  | $2,916.8 |  |  |  | $2,939.4 |  |  |  | $2,950.1 |
Distribution in service | 5,123.5 |  |  | 4,739.2 |  |  | 2,820.9 |  |  | 2,589.3 |  |  | 2,302.6 |  |  | 2,149.9 |
Other in service | 425.1 |  |  | 329.1 |  |  | 282.3 |  |  | 223.5 |  |  | 142.8 |  |  | 105.6 |
Anticipated to be retired early (a)(b) | 93.0 |  |  | 108.3 |  |  | — |  |  | 108.3 |  |  | 93.0 |  |  | — |
Total electric plant | 12,296.9 |  |  | 11,043.5 |  |  | 6,819.1 |  |  | 5,837.9 |  |  | 5,477.8 |  |  | 5,205.6 |
Gas plant in service | 1,244.0 |  |  | 1,107.6 |  |  | 654.8 |  |  | 556.7 |  |  | 589.2 |  |  | 550.9 |
Other plant in service | 571.9 |  |  | 549.3 |  |  | 333.4 |  |  | 313.0 |  |  | 238.5 |  |  | 236.3 |
Accumulated depreciation | (4,283.1 | ) |  | (4,135.7 | ) |  | (2,311.0 | ) |  | (2,258.3 | ) |  | (1,972.1 | ) |  | (1,877.4 | )
Net plant | 9,829.7 |  |  | 8,564.7 |  |  | 5,496.3 |  |  | 4,449.3 |  |  | 4,333.4 |  |  | 4,115.4 |
Leased Sheboygan Falls Energy Facility, net (c) | — |  |  | — |  |  | — |  |  | — |  |  | 46.2 |  |  | 52.4 |
Construction work in progress | 962.2 |  |  | 1,226.8 |  |  | 424.4 |  |  | 968.1 |  |  | 537.8 |  |  | 258.7 |
Other, net | 6.0 |  |  | 18.4 |  |  | 5.5 |  |  | 18.2 |  |  | 0.5 |  |  | 0.2 |
Total utility | 10,797.9 |  |  | 9,809.9 |  |  | 5,926.2 |  |  | 5,435.6 |  |  | 4,917.9 |  |  | 4,426.7 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (d) | 90.9 |  |  | 135.0 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (e) | 345.7 |  |  | 334.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 436.6 |  |  | 469.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment |  | $11,234.5 |  |  |  | $10,279.2 |  |  |  | $5,926.2 |  |  |  | $5,435.6 |  |  |  | $4,917.9 |  |  |  | $4,426.7 |
(a) | In 2017, IPL retired Sutherland Unit 3 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion, including recovery of the remaining net book value of Sutherland Unit 3.
(b) | In 2017, WPL received approval from MISO to retire Edgewater Unit 4 and currently anticipates retiring this EGU by September 30, 2018. In 2016, the PSCW authorized WPL to recover the remaining net book value of Edgewater Unit 4 over a 10-year period beginning the later of the retirement date of the EGU or January 1, 2019.
(c) | Less accumulated amortization of $77.6 million and $71.4 million for WPL as of December 31, 2017 and 2016, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.
(d) | Less accumulated depreciation of $50.5 million and $46.5 million for Alliant Energy as of December 31, 2017 and 2016, respectively. Refer to “Franklin County Wind Farm” below for discussion of the April 2017 transfer of the Franklin County wind farm from AEF to IPL pursuant to a February 2017 FERC order.
(e) | Less accumulated depreciation of $285.6 million and $272.0 million for Alliant Energy as of December 31, 2017 and 2016, respectively.
Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - Construction of Marshalltown, a 706 MW natural gas-fired combined-cycle EGU, began in 2014 and was completed in 2017, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and IPL in 2017. As of December 31, 2017 and 2016, the capitalized project costs for the EGU consisted of capitalized expenditures of $645 million and CWIP of $612 million, and AFUDC of $81 million and $68 million, respectively. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of December 31, 2017 and 2016, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $339 million and $81 million, and AFUDC of $14 million and $2 million, respectively, for West Riverside in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of December 31, 2017 and 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $264 million and $102 million, and AFUDC of $11 million and $1 million, respectively, for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL. Franklin County Wind Farm - In 2016, based on an evaluation of the strategic options for the Franklin County wind farm, Alliant Energy concluded it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet and charges to “Asset valuation charges for Franklin County wind farm” in its income statement in 2016. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of FWEC, which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. In November 2017, WPL filed for approval from the PSCW to acquire the assets of FWEC, and a decision from the PSCW is currently expected in the first half of 2018. In January 2018, FERC approved WPL’s request to acquire the assets of FWEC. Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015. The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate review proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results. AFUDC - AFUDC represents costs to finance construction additions, including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015
Equity |  | $33.6 |  |  |  | $42.3 |  |  |  | $24.4 |  |  |  | $21.1 |  |  |  | $35.2 |  |  |  | $18.6 |  |  |  | $12.5 |  |  |  | $7.1 |  |  |  | $5.8 |
Debt | 16.1 |  |  | 20.2 |  |  | 12.5 |  |  | 10.3 |  |  | 16.8 |  |  | 9.6 |  |  | 5.8 |  |  | 3.4 |  |  | 2.9 |
|  | $49.7 |  |  |  | $62.5 |  |  |  | $36.9 |  |  |  | $31.4 |  |  |  | $52.0 |  |  |  | $28.2 |  |  |  | $18.3 |  |  |  | $10.5 |  |  |  | $8.7 |
Non-utility and Other - The non-utility and other property, plant and equipment recorded on Alliant Energy’s balance sheets includes the following: Non-utility Generation - The Sheboygan Falls Energy Facility was placed into service in 2005 and is depreciated using the straight-line method over a 35-year period. As of December 31, 2017, Alliant Energy recorded $91 million on its balance sheet related to the Sheboygan Falls Energy Facility. Corporate Services and Other - Property, plant and equipment related to Corporate Services includes a customer billing and information system for IPL and WPL and other computer software, and the corporate headquarters building located in Madison, Wisconsin. The customer billing and information system is amortized using the straight-line method over a 12-year period. The majority of the remaining software is amortized over a 5-year period. Property, plant and equipment related to Transportation includes a short-line railway in Iowa and a barge terminal on the Mississippi River. The Corporate Services and Other property, plant and equipment is depreciated using the straight-line method over periods ranging from 5 to 30 years.
IPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2017 |  | 2016 |  | 2017 |  | 2016
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service |  | $6,655.3 |  |  |  | $5,866.9 |  |  |  | $3,715.9 |  |  |  | $2,916.8 |  |  |  | $2,939.4 |  |  |  | $2,950.1 |
Distribution in service | 5,123.5 |  |  | 4,739.2 |  |  | 2,820.9 |  |  | 2,589.3 |  |  | 2,302.6 |  |  | 2,149.9 |
Other in service | 425.1 |  |  | 329.1 |  |  | 282.3 |  |  | 223.5 |  |  | 142.8 |  |  | 105.6 |
Anticipated to be retired early (a)(b) | 93.0 |  |  | 108.3 |  |  | — |  |  | 108.3 |  |  | 93.0 |  |  | — |
Total electric plant | 12,296.9 |  |  | 11,043.5 |  |  | 6,819.1 |  |  | 5,837.9 |  |  | 5,477.8 |  |  | 5,205.6 |
Gas plant in service | 1,244.0 |  |  | 1,107.6 |  |  | 654.8 |  |  | 556.7 |  |  | 589.2 |  |  | 550.9 |
Other plant in service | 571.9 |  |  | 549.3 |  |  | 333.4 |  |  | 313.0 |  |  | 238.5 |  |  | 236.3 |
Accumulated depreciation | (4,283.1 | ) |  | (4,135.7 | ) |  | (2,311.0 | ) |  | (2,258.3 | ) |  | (1,972.1 | ) |  | (1,877.4 | )
Net plant | 9,829.7 |  |  | 8,564.7 |  |  | 5,496.3 |  |  | 4,449.3 |  |  | 4,333.4 |  |  | 4,115.4 |
Leased Sheboygan Falls Energy Facility, net (c) | — |  |  | — |  |  | — |  |  | — |  |  | 46.2 |  |  | 52.4 |
Construction work in progress | 962.2 |  |  | 1,226.8 |  |  | 424.4 |  |  | 968.1 |  |  | 537.8 |  |  | 258.7 |
Other, net | 6.0 |  |  | 18.4 |  |  | 5.5 |  |  | 18.2 |  |  | 0.5 |  |  | 0.2 |
Total utility | 10,797.9 |  |  | 9,809.9 |  |  | 5,926.2 |  |  | 5,435.6 |  |  | 4,917.9 |  |  | 4,426.7 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (d) | 90.9 |  |  | 135.0 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (e) | 345.7 |  |  | 334.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 436.6 |  |  | 469.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment |  | $11,234.5 |  |  |  | $10,279.2 |  |  |  | $5,926.2 |  |  |  | $5,435.6 |  |  |  | $4,917.9 |  |  |  | $4,426.7 |
(a) | In 2017, IPL retired Sutherland Unit 3 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion, including recovery of the remaining net book value of Sutherland Unit 3.
(b) | In 2017, WPL received approval from MISO to retire Edgewater Unit 4 and currently anticipates retiring this EGU by September 30, 2018. In 2016, the PSCW authorized WPL to recover the remaining net book value of Edgewater Unit 4 over a 10-year period beginning the later of the retirement date of the EGU or January 1, 2019.
(c) | Less accumulated amortization of $77.6 million and $71.4 million for WPL as of December 31, 2017 and 2016, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.
(d) | Less accumulated depreciation of $50.5 million and $46.5 million for Alliant Energy as of December 31, 2017 and 2016, respectively. Refer to “Franklin County Wind Farm” below for discussion of the April 2017 transfer of the Franklin County wind farm from AEF to IPL pursuant to a February 2017 FERC order.
(e) | Less accumulated depreciation of $285.6 million and $272.0 million for Alliant Energy as of December 31, 2017 and 2016, respectively.
Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - Construction of Marshalltown, a 706 MW natural gas-fired combined-cycle EGU, began in 2014 and was completed in 2017, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and IPL in 2017. As of December 31, 2017 and 2016, the capitalized project costs for the EGU consisted of capitalized expenditures of $645 million and CWIP of $612 million, and AFUDC of $81 million and $68 million, respectively. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of December 31, 2017 and 2016, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $339 million and $81 million, and AFUDC of $14 million and $2 million, respectively, for West Riverside in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of December 31, 2017 and 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $264 million and $102 million, and AFUDC of $11 million and $1 million, respectively, for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL. Franklin County Wind Farm - In 2016, based on an evaluation of the strategic options for the Franklin County wind farm, Alliant Energy concluded it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet and charges to “Asset valuation charges for Franklin County wind farm” in its income statement in 2016. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of FWEC, which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. In November 2017, WPL filed for approval from the PSCW to acquire the assets of FWEC, and a decision from the PSCW is currently expected in the first half of 2018. In January 2018, FERC approved WPL’s request to acquire the assets of FWEC. Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015. The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate review proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results. AFUDC - AFUDC represents costs to finance construction additions, including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015
Equity |  | $33.6 |  |  |  | $42.3 |  |  |  | $24.4 |  |  |  | $21.1 |  |  |  | $35.2 |  |  |  | $18.6 |  |  |  | $12.5 |  |  |  | $7.1 |  |  |  | $5.8 |
Debt | 16.1 |  |  | 20.2 |  |  | 12.5 |  |  | 10.3 |  |  | 16.8 |  |  | 9.6 |  |  | 5.8 |  |  | 3.4 |  |  | 2.9 |
|  | $49.7 |  |  |  | $62.5 |  |  |  | $36.9 |  |  |  | $31.4 |  |  |  | $52.0 |  |  |  | $28.2 |  |  |  | $18.3 |  |  |  | $10.5 |  |  |  | $8.7 |
WPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2017 |  | 2016 |  | 2017 |  | 2016
Utility: |  |  |  |  |  |  |  |  |  |  |
Electric plant: |  |  |  |  |  |  |  |  |  |  |
Generation in service |  | $6,655.3 |  |  |  | $5,866.9 |  |  |  | $3,715.9 |  |  |  | $2,916.8 |  |  |  | $2,939.4 |  |  |  | $2,950.1 |
Distribution in service | 5,123.5 |  |  | 4,739.2 |  |  | 2,820.9 |  |  | 2,589.3 |  |  | 2,302.6 |  |  | 2,149.9 |
Other in service | 425.1 |  |  | 329.1 |  |  | 282.3 |  |  | 223.5 |  |  | 142.8 |  |  | 105.6 |
Anticipated to be retired early (a)(b) | 93.0 |  |  | 108.3 |  |  | — |  |  | 108.3 |  |  | 93.0 |  |  | — |
Total electric plant | 12,296.9 |  |  | 11,043.5 |  |  | 6,819.1 |  |  | 5,837.9 |  |  | 5,477.8 |  |  | 5,205.6 |
Gas plant in service | 1,244.0 |  |  | 1,107.6 |  |  | 654.8 |  |  | 556.7 |  |  | 589.2 |  |  | 550.9 |
Other plant in service | 571.9 |  |  | 549.3 |  |  | 333.4 |  |  | 313.0 |  |  | 238.5 |  |  | 236.3 |
Accumulated depreciation | (4,283.1 | ) |  | (4,135.7 | ) |  | (2,311.0 | ) |  | (2,258.3 | ) |  | (1,972.1 | ) |  | (1,877.4 | )
Net plant | 9,829.7 |  |  | 8,564.7 |  |  | 5,496.3 |  |  | 4,449.3 |  |  | 4,333.4 |  |  | 4,115.4 |
Leased Sheboygan Falls Energy Facility, net (c) | — |  |  | — |  |  | — |  |  | — |  |  | 46.2 |  |  | 52.4 |
Construction work in progress | 962.2 |  |  | 1,226.8 |  |  | 424.4 |  |  | 968.1 |  |  | 537.8 |  |  | 258.7 |
Other, net | 6.0 |  |  | 18.4 |  |  | 5.5 |  |  | 18.2 |  |  | 0.5 |  |  | 0.2 |
Total utility | 10,797.9 |  |  | 9,809.9 |  |  | 5,926.2 |  |  | 5,435.6 |  |  | 4,917.9 |  |  | 4,426.7 |
Non-utility and other: |  |  |  |  |  |  |  |  |  |  |
Non-utility Generation, net (d) | 90.9 |  |  | 135.0 |  |  | — |  |  | — |  |  | — |  |  | — |
Corporate Services and other, net (e) | 345.7 |  |  | 334.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total non-utility and other | 436.6 |  |  | 469.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total property, plant and equipment |  | $11,234.5 |  |  |  | $10,279.2 |  |  |  | $5,926.2 |  |  |  | $5,435.6 |  |  |  | $4,917.9 |  |  |  | $4,426.7 |
(a) | In 2017, IPL retired Sutherland Unit 3 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion, including recovery of the remaining net book value of Sutherland Unit 3.
(b) | In 2017, WPL received approval from MISO to retire Edgewater Unit 4 and currently anticipates retiring this EGU by September 30, 2018. In 2016, the PSCW authorized WPL to recover the remaining net book value of Edgewater Unit 4 over a 10-year period beginning the later of the retirement date of the EGU or January 1, 2019.
(c) | Less accumulated amortization of $77.6 million and $71.4 million for WPL as of December 31, 2017 and 2016, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.
(d) | Less accumulated depreciation of $50.5 million and $46.5 million for Alliant Energy as of December 31, 2017 and 2016, respectively. Refer to “Franklin County Wind Farm” below for discussion of the April 2017 transfer of the Franklin County wind farm from AEF to IPL pursuant to a February 2017 FERC order.
(e) | Less accumulated depreciation of $285.6 million and $272.0 million for Alliant Energy as of December 31, 2017 and 2016, respectively.
Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - Construction of Marshalltown, a 706 MW natural gas-fired combined-cycle EGU, began in 2014 and was completed in 2017, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and IPL in 2017. As of December 31, 2017 and 2016, the capitalized project costs for the EGU consisted of capitalized expenditures of $645 million and CWIP of $612 million, and AFUDC of $81 million and $68 million, respectively. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of December 31, 2017 and 2016, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $339 million and $81 million, and AFUDC of $14 million and $2 million, respectively, for West Riverside in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of December 31, 2017 and 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $264 million and $102 million, and AFUDC of $11 million and $1 million, respectively, for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL. Franklin County Wind Farm - In 2016, based on an evaluation of the strategic options for the Franklin County wind farm, Alliant Energy concluded it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet and charges to “Asset valuation charges for Franklin County wind farm” in its income statement in 2016. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of FWEC, which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. In November 2017, WPL filed for approval from the PSCW to acquire the assets of FWEC, and a decision from the PSCW is currently expected in the first half of 2018. In January 2018, FERC approved WPL’s request to acquire the assets of FWEC. Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015. The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate review proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results. AFUDC - AFUDC represents costs to finance construction additions, including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015 |  | 2017 |  | 2016 |  | 2015
Equity |  | $33.6 |  |  |  | $42.3 |  |  |  | $24.4 |  |  |  | $21.1 |  |  |  | $35.2 |  |  |  | $18.6 |  |  |  | $12.5 |  |  |  | $7.1 |  |  |  | $5.8 |
Debt | 16.1 |  |  | 20.2 |  |  | 12.5 |  |  | 10.3 |  |  | 16.8 |  |  | 9.6 |  |  | 5.8 |  |  | 3.4 |  |  | 2.9 |
|  | $49.7 |  |  |  | $62.5 |  |  |  | $36.9 |  |  |  | $31.4 |  |  |  | $52.0 |  |  |  | $28.2 |  |  |  | $18.3 |  |  |  | $10.5 |  |  |  | $8.7 |

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