Interstate Power and Light Company to permanently reduce greenhouse gas emissions

Company to retire older coal-fired power plants and switch Dubuque Generating Station fuel source to natural gas in 2013

Interstate Power and Light Company (IPL), a subsidiary of Alliant Energy Corporation (NYSE: LNT), proposed today to permanently reduce its generating fleet’s greenhouse gas emissions by retiring coal-fired generating units and switching the fuel source of other coal-fired units to natural gas when its proposed Sutherland Generating Station Unit 4 becomes operable in 2013.

The proposed changes to IPL’s generating fleet will be filed with the Iowa Utilities Board (IUB) as part of IPL’s application for ratemaking principles for the proposed Sutherland Generating Station Unit 4 and are subject to the approval of the IUB and the Minnesota Public Utility Commission. IPL expects to make the filing late first quarter of 2008.

IPL expects that the generating station retirements and fuel switch at the Dubuque power facility will have no impact upon current employees.

“We, alone, have an obligation to serve our customers and this plan fulfills that obligation by providing our customers with safe, reliable and environmentally responsible energy,” states Tom Aller, president of IPL. “Our proposal improves Iowa’s air quality and environment while providing a reliable energy supply to support the growth of Iowa’s economy. We are preparing Iowa for a bright energy future by confronting the challenges of greenhouse gas emissions and ensuring a reliable energy supply today.”

As part of its greenhouse gas emissions reduction proposal, IPL will retire Lansing Generating Station’s coal-fired units 2 and 3. In addition, the company will permanently switch the fuel source of its Dubuque Generating Station Units from coal to natural gas. This will reduce these units’ maximum potential to emit CO2 by more than 800,000 tons per year. These potential changes in IPL’s generating fleet are contingent upon the company receiving all applicable regulatory approvals related to Sutherland Generating Station Unit 4’s site certification and ratemaking principles applications.

IPL estimates that its energy efficiency programs, which include the new five-year plan the company expects to file with the IUB later this year, will reduce customers’ electric usage by nearly 2 million megawatt-hours by 2013. As a result, IPL’s system-wide CO2 emissions are expected to be reduced by approximately 2.57 million tons per year compared to what those emission levels would be absent the company’s energy efficiency programs.

IPL recently received approval to build 200 MW of wind generation in Iowa by 2013 that will also serve to reduce the Company’s system-wide CO2 emission levels by approximately 934,000 tons per year in 2013 from what those emissions levels would be absent this investment.

In addition, Sutherland Generating Station Unit 4 is being permitted to utilize up to five percent renewables, such as switch grass or corn stalks, as fuel and, as such, can be considered a hybrid facility. The facility’s CO2 emissions levels do not increase from the use of renewables as a fuel source. As a result, CO2 emissions from Sutherland Generating Station Unit 4 are reduced by an additional 156,000 tons per year when the fuel source is economically available for use at the facility.

IPL’s 350 megawatt ownership share of Sutherland Generating Station Unit 4 has the maximum potential to emit approximately 3.1 million tons of CO2 annually under its air permit application. IPL’s proposal to retire or fuel switch less efficient coal-fired generating stations, aggressively pursue energy efficiency and invest in renewables is expected to more than offset Sutherland Generating Station Unit 4’s expected CO2 emissions in 2013 when the facility is operational.

“Since our initial announcement in January 2007, our proposal has focused on doing what is right for our customers and Iowa,” adds Mr. Aller. The cost of ‘saying no’, as some have advocated, to securing a reliable energy supply that is environmentally responsible for our customers and Iowa is not an option.”

“Our proposal adds a highly efficient generating station that uses renewables as a fuel source, expands our renewable energy portfolio, advances our nationally recognized energy efficiency programs, provides the ability to switch fuel sources on some existing coal power plants, and retire others. As a result, this plan is the right option for our customers and the state of Iowa. The plan is about providing practical energy solutions that will enhance our environment and grow our economy for future generations of Iowans.”