CHEYENNE (AP) -- Two large power lines would take electricity from Wyoming through Utah and into Arizona under an agreement between the Wyoming Infrastructure Authority and Arizona's largest electric company to collaborate on construction.

The memorandum of understanding, signed this week by Arizona Public Service Company, National Grid USA and the Wyoming Infrastructure Authority, is a first step toward completing the TransWest Express Project.

Arizona Public Service wants two 500,000-volt transmission lines that would feed electricity to Arizona's booming urban areas from coal-fired power plants and wind-generation fields in Wyoming.

"Our region needs and my state needs renewables and clean coal generation resources," Arizona Gov. Janet Napolitano said in a news release.

Wyoming already is working with National Grid to study electric transmission projects coming out of the state.

"Throughout the West there is increasing interest in Wyoming as a source of power supply," said Steve Waddington, executive director of the Wyoming Infrastructure Authority. "Today's announcement is a significant step forward in building the multistate cooperation necessary to ensure that the required transmission lines interconnecting the West are built."

Based in Phoenix, Arizona Public Service has about 1 million customers in 11 of the state's 15 counties.