UniSource Energy Services (UES), an indirect, wholly owned subsidiary of Fortis Inc., has strengthened its generating portfolio and reduced its reliance on the wholesale energy market through the purchase of a share of the efficient natural gas-fired Gila River Power Station in Gila Bend. Under the terms of the purchase, UES subsidiary UNS Electric, Inc. and sister company Tucson Electric Power (TEP) acquired the 550-megawatt (MW) Gila River Power Station Power Block 3 from Gila River Power LLC for US$219 million. UNS Electric will control 137 MW of the unit's energy, while TEP will own the remaining output. "This acquisition contributes to an evolving resource portfolio that will provide reliable…