Interstate Power and Light Company files application with Iowa Utilities Board for proposed Iowa wind facilities

Company takes steps to position Iowa as leader in renewable energy

Interstate Power and Light Co. (IPL), an Alliant Energy company (NYSE: LNT), filed with the Iowa Utilities Board (IUB) today an application for ratemaking principles concerning the company’s proposed construction of up to 200 megawatts of wind powered generating facilities in Iowa.

“Wind generation in Iowa is a critical component of our renewable energy portfolio,” states Tom Aller, president of IPL. “IPL is committed to enhancing the state’s renewable energy economy through our build-out of wind generation. Our wind generation projects support Governor Culver’s vision of growing the state’s bio-economy, creating new jobs and helping make Iowa a leader in renewable energy capital.”

As part of IPL’s long-term generation plan, the company is seeking to expand its renewable energy portfolio in Iowa. As a result, IPL is currently exploring various sites across its service area for wind development opportunities. Upon completion of the site selection process, IPL expects to begin construction in 2009.

Given the substantial capital investment required to complete the IPL wind project, the company is seeking the IUB’s approval that the proposed ratemaking principles are reasonable prior to investing in the project. Ratemaking principles are fixed and define how the costs associated with building wind facilities will be recovered in utility rates throughout the life of the project.

The company expects to invest approximately $360 to $440 million on up to 200 megawatts of company-owned wind by year-end 2010. IPL is requesting a 12.3 percent return on equity as part of the filing.

IPL expects to receive an IUB decision on its application for ratemaking principles in the first quarter of 2008.

Upon completion of the IPL wind project, approximately 6 percent of IPL’s electricity will be generated from renewable energy sources through either purchased power agreements or company-owned renewable generation. More than 90 percent of IPL’s renewable energy will be derived from wind generation.

In January 2007, Interstate Power and Light (IPL) announced details of its ‘Energy for a New Generation’ plan. Energy efficiency initiatives and wind energy are key components of the long-term generation plan.