The electric utility ,Ameren UE,last week signed an agreement to buy wind power from Horizon Wind Energy's Pioneer Prairie Wind Farm in Iowa.This is Ameren's first purchase of wind power .Ameren UE's proposed energy purchase of a 102 MW from Horizon Wind is enough to power 26,000 households.It was only after a multi-year review of proposas that Ameren UE chose to purchase wind energy from Horizon amounting to one thrid of the Pioneer Prairie Wind Farm output . The second phse of the Pioneer Prairie Wind Farm is located in Mitchell county ,Iowa .The wind farm spans approximately 10,000 acres and is comprised of 62 Vestas V82 wind turbines that produce 1.65MW each .The second phase of the Pioneer Prairie Wind Farm began full operations in January 2009. Ameren said the energy purchased from Horizon would tie into its Midwest Independent system Operator-Miso -Transmission grid of which the it is a member ,fulfilling ,its commitment to add 100MW of renewable capcity to serve its Missouri customers by 2010 . Ameren UE--Missouri's largest electric utility --provides electric service to approximately 1.2 million customers across central and eastern Missouri ,including the greater ST.Lousi area .UE serves 57 Missouri counties and 500 towns .More than haft(55%) of UE'S electric customers are located in the St.Louis metropolitan area.