BISBEE — With the burgeoning population growth in Arizona and the growing inclination to turn to renewable energy sources, some improvements are going to have to be made to the capacity of the transmission grid.

This map shows the proposed route of a new power transmission line in the SunZia transmission line project.

SouthWestern Power Group announced Monday an agreement with four partners to proceed with development of the SunZia Southwest Transmission Project, a proposed high-capacity electrical transmission line between Arizona and New Mexico.

So, the new transmission line planned by the partnership consisting of SWPG, Salt River Project, Tucson Electric Power, Energy Capital Partners and Shell Wind-Energy Inc. may provide additional delivery options for the Bowie Power Station. It also may provide a pathway for renewable energy production in Southern Arizona, said Ian Calkins, public relations contact for SWPG.

“SunZia will provide new delivery paths to electricity markets for existing and developing energy resources, primarily renewable resources such as wind, solar and geothermal projects,” he said.

 “This will create new opportunities for renewable energy sources to tie in to the high energy transmission line. The project also substantially improves the efficiency and reliability of power transfers across the transmission grid in the West.”

The Southwest Area Transmission Group, a regional transmission planning organization, originally identified the need for a new transmission line based on regional population growth projections, increased system transfer and import capability requirements, and growing energy demands for renewable energy resources, Calkins said.

“SWAT promotes coordinated regional planning of the transmission grid in the desert Southwest and includes transmission owners and users, environmental interests and governmental organizations,” he said.

Tom Wray, who also is with SWPG and is SunZia’s project manager, said there is more than power transmission in the project.

“In addition to promoting development of wind, solar and geothermal energy production, by creating regional access to these renewable resources, SunZia increases the reliability of the underlying extra high-voltage transmission system in southern New Mexico and Southern Arizona,” he said. “SunZia will help create a critical link between existing and planned transmission and generation facilities, while providing new opportunities for the efficient delivery of new resources to meet growing power demands in the Southwest.”

SWPG will act as project manager, overseeing the permitting, environmental studies and engineering design of the SunZia Transmission Project, Calkins said. When fully developed, the 500-mile SunZia transmission line project will provide an expected 3,000 megawatts of new transmission capacity.

The specific alignment of the transmission line will be determined after detailed evaluation of alternative transmission system configurations and routes. Northern Cochise County along Interstate 10 is in the study area, according to the SunZia Web site.

The group is set to begin the local, state and federal permitting efforts. Calkins indicated there would be an extensive public involvement process.

If all goes as planned, the first phase will be ready for commercial operation by 2013.