Recent Press Release

Interstate Power and Light Company commits $400,000,000 to energy efficiency programs over next five years

Five-year plan includes new programs and greater incentives for customers to conserve energy

CEDAR RAPIDS, Iowa – April 23, 2008 – Interstate Power and Light Company (IPL), a subsidiary of Alliant Energy Corporation (NYSE: LNT), filed with the Iowa Utilities Board (IUB) today its proposed 2009-2013 Energy Efficiency Plan (EEP). The proposed EEP includes a commitment of approximately $400 million to electric and natural gas energy efficiency customer programs over the next five years.

See our IPL Energy Efficiency Plan (EEP-08-1) regulatory filing documents.

“Our company’s long-term energy efficiency strategy plays a role in meeting our customers’ future energy needs,” says Tom Aller, president of IPL. “Our company is committed to pursuing energy options for our customers that are safe, reliable, affordable and environmentally responsible. Energy efficiency is a practical energy option that provides our customers with the opportunity to conserve energy while making a positive impact upon our environment.”

IPL’s proposed five-year EEP includes programs for residential, agricultural, commercial and industrial electric and natural gas customers. The proposed EEP offers many of the cash rebate and energy audit programs currently offered by IPL. In addition, the proposed plan includes:

• Five-year cumulative electric energy savings goals conserving enough energy to power approximately 88,000 homes for one year
• Five-year cumulative natural gas energy savings goals conserving enough energy to serve more than 19,000 homes with natural gas for one year
• Comprehensive, whole-house energy-efficiency cash rebate program for existing homes
• Incentives for Leadership in Energy and Environmental Design (LEED) certification
• Expanded energy-efficiency educational opportunities
• Enhanced cash rebate and audit programs for residential customers with limited incomes
• New renewable programs which include financial and technical assistance to conduct feasibility studies and cash rebates to install equipment

IPL expects to receive an IUB decision on its proposed 2009-2013 EEP in the fourth quarter of 2008.

“We are proud to play a part in positioning Iowa for a bright energy future with a comprehensive energy plan that benefits our customers and Iowa’s economy and environment,” adds Aller. “Our investments in new baseload generation, renewable energy resources and energy efficiency, combined with our retirement and fuel-switching of less-efficient power plants, will permanently reduce our company’s CO2 emissions in 2013 when comparing it to IPL’s current CO2 intensity levels. We are proud to present a long-term strategy that provides economic development opportunities and preserves our environment for future generations of Iowans.”

IPL’s Iowa electric and natural gas customers will be receiving additional information on the company’s proposed EEP in the mail. Additional information on IPL’s proposed EEP or other energy-saving tips is available by calling 1-800-723-7635 or at powerhousetv.com or alliantenergy.com.

See our IPL Energy Efficiency Plan (EEP-08-1) regulatory filing documents.

This press release includes forward-looking statements. These forward-looking statements can be identified as such because the statements include words such as “expects, “plans,” “approximately” or other words of similar import. Similarly, statements that describe future plans, designs 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 or federal regulatory actions or local government actions, including inability to obtain all necessary approvals and permits; unanticipated construction issues, delays or expenditures; failure of equipment, technology or programs to perform as expected; current or future litigation, regulatory investigations, proceedings or inquiries that could impede the implementation of the IPL's plans; political conditions in IPL's service territories; and economic conditions in IPL'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 IPL undertake no obligation to update publicly such statements to reflect subsequent events or circumstances.

Media Contact: Ryan Stensland (319) 786-4171
Investor Relations: Jamie Freeman (608) 458-3274