Black Mountain Generating Station

Need

UniSource buys much of its power from other providers on the regional energy market. Reliable energy is becoming increasingly unavailable in the desert Southwest, particularly during extreme summer heat.  From 2015 to 2021, customers’ peak energy demands increased by 16 percent and we expect strong demand for energy to continue over the next five years.

To preserve the reliability and affordability of our service in the face of growing demand and significantly reduced resource availability on the southwestern regional grid, we must invest in additional resources. UniSource’s 2023 Integrated Resource Plan (IRP) calls for additional renewable, storage and natural gas generating resources by 2038.

Benefits

By expanding local generating capacity, UniSource reduces the need to buy power from the market. Additional capacity will support economic growth and job creation in the Mohave County area. A new, local generating resource will help meet expanding energy needs.

Local generating resources will provide grid stability throughout the Mohave County area. Natural gas-fired turbines, similar to those already in use at Black Mountain Generating Station, can adjust output quickly to meet changing customer energy needs. New natural gas-fired units can provide affordable, around-the-clock reliability for customers today and in the future, reducing costs associated with purchasing energy and transmission across facilities owned by other companies.

Project Description

UniSource is considering the addition of four 50 megawatt (MW) natural gas-fired turbines equipped with state-of-the-art emission controls at Black Mountain. These systems use substantially less water than a conventional steam turbine or a combined cycle plant, minimizing aquifer withdrawals.

Currently, the company is in the due diligence phase, collecting and analyzing information, and identifying air permit and plant and line siting requirements before making a final decision to move forward. UniSource will weigh this option against others submitted in response to an anticipated all-source request for proposals later this year.

Under Arizona law, individual generating units under 100 megawatts (MW) do not require a certificate of environmental compatibility (CEC). The two existing 45-MW natural gas units at Black Mountain were constructed without a CEC because the capacity of each is below the 100 MW threshold. As such, UniSource is asking the Arizona Power Plant and Transmission Line Siting Committee to disclaim jurisdiction over the potential expansion.

Prehearing Conference – April 16, 2024

• Transcript

Procedural Conference – April 8, 2024

• Transcript

Prefiling Conference – Feb. 28, 2024

• Transcript
• Exhibits 1-5

Application for a Disclaimer of Jurisdiction, or, in the Alternative, a Certificate of Environmental Compatibility

• Application

• Click here for a PDF of the Map

UniSource encourages residents, property owners, businesses and others to share their input by:

• Filling out an online comment form
• Sending email comments to blackmountain@uesaz.com
• Calling 1-928-681-6500 and leaving a voicemail message
• Mailing a letter with comments to:

UniSource
ATTN: Black Mountain
P.O. Box 711
Mail Stop CB200
Tucson, AZ 85701-0711