The ink is dry on a key agreement between Interstate Power and Light Co. and the Duane Arnold Energy Center.

The Alliant Energy utility subsidiary announced Wednesday the signing of an 11-year contract to purchase 431 megawatts of power from NextEra Energy’s nuclear power plant near Palo. The deal goes into effect in February 2014.

Alliant spokesman Ryan Stensland said the new cost to purchase power from the nuclear plant will be about 30 percent lower than the previous contract, following a competitive bid process. He said customers may notice some small reductions to their bills, but a variety of other factors, including other fuel costs, make that uncertain.

The deal provides IPL with reliable, emissions-free power and supports the local economy, the company said. About 600 employees work at the Duane Arnold plant.

“It’s Iowa power, being produced by Iowans for Iowans,” Stensland said. “It’s all positive.”