Alliant Energy: Wisconsin Power and Light Co. makes wind filings in Minnesota

Media Contact: Steve Schultz (608) 458-3285

Investor Relations: Jamie Freeman (608) 458-3274

Bent Tree Wind Farm has the potential to power approximately 100,000 homes

Madison, WI – June 30, 2008 – Wisconsin Power and Light Company (WPL), a subsidiary of Alliant Energy Corporation (NYSE: LNT), has filed both a Site Permit application and Certificate of Need (CON) application with the Minnesota Public Utilities Commission (MPUC) for the Bent Tree Wind Farm, a proposed wind farm in Freeborn County, Minnesota.

The Bent Tree Wind Farm has the potential to produce up to 400 megawatts (MW) of emissions-free energy, which is enough to power approximately 100,000 homes.

While WPL’s Site Permit application seeks MPUC approval for a 400 MW wind farm, WPL currently plans to develop 200 MW beginning in 2009. A decision regarding the development of the wind farm’s additional 200 MW has not yet been made. Pending all regulatory approvals, WPL anticipates 200 MW of the Bent Tree Wind Farm will be commercially operable by the end of 2010. The 200 MW project will cost approximately $450 to $475 million, excluding allowance for funds used during construction.

In April, WPL executed a letter of intent to purchase the site for Bent Tree Wind Farm from Wind Capital Group, LLC. WPL currently anticipates the purchase of the site to be complete by year end 2008.

WPL filed a Certificate of Public Convenience and Necessity (CPCN) application with the Public Service Commission of Wisconsin (PSCW) earlier this month and expects the PSCW to issue a ruling on its application by the end of the year. WPL expects the MPUC to issue rulings on its Site Permit and CON applications in late 2008 or early 2009.

Alliant Energy is an energy-services provider with subsidiaries serving approximately 1 million electric and 400,000 natural gas customers. Providing its customers in the Midwest with regulated electric and natural gas service is the company’s primary focus. Wisconsin Power and Light, the company’s Wisconsin utility subsidiary, serves approximately 450,000 electric and 175,000 natural gas customers. Alliant Energy, headquartered in Madison, Wis., is a Fortune 1000 company traded on the New York Stock Exchange under the symbol LNT. For more information, visit the company’s Web site at

This press release includes forward-looking statements. These forward-looking statements can be identified as such because the statements include words such as “anticipates,” “approximately,” “expects,” or other words of similar import. Similarly, statements that describe future plans or strategies are also forward-looking statements. Such statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those currently anticipated. Actual results could be affected by such factors as: state regulatory actions or local government actions which delay, prevent or alter the proposed plans, including inability to obtain all necessary approvals and permits; unsuccessful negotiations for the purchase of the wind farm; unanticipated construction issues, delays or expenditures; including increased costs of labor, materials and equipment; failure of equipment and technology to perform as expected; current or future litigation, regulatory investigations, proceedings or inquiries that could impede the implementation of WPL’s plans; political conditions in WPL’s service territories; changes to WPL’s access to capital markets; and economic conditions in WPL’s service territory. These factors should be considered when evaluating the forward-looking statements and undue reliance should not be placed on such statements. The forward-looking statements included herein are made as of the date hereof and Alliant Energy and WPL undertake no obligation to update publicly such statements to reflect subsequent events or circumstances.