Alliant Energy subsidiary Interstate Power and Light has reached a settlement with the US Environmental Protection Agency (EPA) and US Department of Justice (DOJ) to reduce emissions from its seven coal-fired power plants in Iowa.
Under the settlement, the power firm will also need to spend $6m for environmental mitigation measures, and pay a civil penalty of $1.1m as compensation for alleged violations of the Clean Air Act.
Interstate Power and Light will install new pollution control technology and continuously operate the technology at its two of its facilities in Lansing and Ottumwa.
Five other plants in Burlington, Cedar Rapids, Clinton, Dubuque, and Marshalltown have been instructed to be shutdown or be converted to cleaner-burning natural gas.
Interstate might need to invest around $620m for the recommended pollution control upgrades, which are aimed at lowering sulphur dioxide (SO2) and nitrogen oxide (NOx) emissions from the power projects.
The firm will need to choose from five potential projects to spend the assigned $6m.
The projects include solar energy and anaerobic digester installations, replacing coal-fired boilers at schools with lower-emission equipment, an alternative fuel vehicle replacement program, and a programme to help residents change wood burning stoves and fireplaces.
EPA Office of Enforcement and Compliance Assurance assistant administrator Cynthia Giles said: "To serve the communities in which they operate, power plants must protect clean air for those living nearby.
"This case delivers on the goals of EPA’s national enforcement initiative to reduce air pollution from the largest sources. By installing new equipment and funding mitigation projects, Interstate Power and Light can help conserve energy and cut pollution in communities across Iowa."