Apache Generating Station

Apache Generating Station generates a total of 625 MW near Cochise, Arizona. AEPCO continues to diversify its energy portfolio. In addition to natural gas and coal units, we generate 20 MW of renewable energy at Apache Solar Project at Apache Station.

AEPCO owns Apache Generating Station at Cochise, Arizona, south of Willcox and east of Benson. Apache Station has:

  • 625 megawatts of combined gross generating capacity
  • 3 steam generating units: ST1 and ST2 burn natural gas as a primary fuel; ST3 has the capability of burning either coal or natural gas alone as primary fuels, and can burn both in combination
  • 4 gas turbines
John Keith, left, Martin Smith and other Apache Station team members are critical to operating our newly converted natural gas unit, ST2.

In 2017, ST2 was converted from burning coal to pipeline natural gas as its primary fuel. We also upgraded ST3 to reduce emissions. Employees work in three shifts around the clock at the plant to deliver a reliable source of electric power.

  • 6 Class Member distribution cooperatives in southern Arizona, western New Mexico, northwestern Arizona and California receive wholesale power from Apache Station
  • Apache Station provides power to more than 161,000 meters representing more than 420,000 individual residential, commercial, agricultural and industrial member/consumers.
  • AEPCO is one of 63 generation and transmission electric cooperatives in the nation.

Innovation at Apache Generating Station

David Landwerlen
David Landwerlen, manager of instrument and electrical maintenance, developed a process with his team to customize and optimize a vital tool—a distributive control system—to automatically blend coal and natural gas in the most efficient way possible. As he explains, a co-burn uses two different fuels to generate steam. A co-burn using coal is more complicated because It can blend three or four different types of coals, and then blend them with natural gas.

Innovation is essential to the continuing success of any organization committed to managing costs as markets and operating conditions change. Modernizing control systems to improve the efficiency and flexibility of generating resources at Apache Station is an example of this sort of innovation, which allows us to benefit fully from fuel shifting.

Mike Nelson, executive director of power production, speaks to employees at Apache Generating Station. Pat Middlebrook, maintenance planning and reliability manager is at Nelson’s right. Apache Station personnel, our Energy Services and the ACES WRTC staff worked around the clock to assure all Apache generation remained on line during record peak demand in the summer of 2020. A power crisis throughout the West was fueled by extreme heat, wildfires and capacity margins.

Apache Generating Station can burn 100% gas when gas prices are low, burn 100% coal when gas prices are high, or burn any combination of coal and gas in response to rapidly changing market conditions. This allows AEPCO to take advantage of fluctuations in the price of natural gas. Other benefits include optimizing coal combustion or more precisely controlling emissions. Being able to quickly switch from natural gas back to coal also ensures AEPCO can continue to generate power reliably, even during significant disruptions in natural gas deliveries and natural gas price spikes, such as the one much of the country experienced during the Texas power crisis in February 2021.

The Apache Station team also recently detected a manufacturing defect that caused a high rate of fuse failures at our Apache Solar 20-MW facility. The team developed cutting-edge technology to decrease the time required to identify and address problems, leading to cost savings and enhanced reliability.

Steam Unit 3 Can Co-Fire Coal and Gas

illustration: 4 coal burning parts and two interspersed gas burning parts. Text: "Front of Boiler. (Rear identical)"
ST3 is one of the most flexible generating units in the industry, with the ability to burn coal and natural gas at the same time. This flexibility enables us to take advantage of the lowest fuel prices available, holding down generating costs for our Members.

Positioning for the Future

From reducing fuel costs to implementing new efficiencies, we are positioning Arizona G&T Cooperatives to become even more competitive. At the same time, we maintain our strong commitment to the environment, reliability and safety.

Complying with environmental regulations is a big part of our job. Learn more in our Environment section. The public is invited to enjoy our Apache Station Wildlife Viewing Area.

Apache Generating Station Beats Industry Reliability Averages

AEPCO has a strong track record of reliability performance scores that rank well above industry averages. The following is a Combined Forced Outage Rate Report for Apache Generating Station ST2 & ST3.

Industry standard 2010–2018: 8%. Apache Generating Station Rate: 2010: 0.94%, 2011: 1.08%, 2012: 1.62%, 2013: 2.65%, 2014: 1.8%, 2015: 0.69%, 2016: 3.81%, 2017: 2.89%, 2018 (January through September): 1.77%

Fast Facts About Steam Units 2 and 3

  • 3.4 million feet of electric cable, equal to 644 miles
  • 43,394 cubic yards of concrete, equal to 450 miles of sidewalk
  • 194,700 KVA capacity of GE turbine-generator
  • 3,600 RPM
  • 2,400 PSIG
  • 1.3 million lbs/hour at 1,005 F: steam generation
  • 192 feet: height of steam units
  • 2,400 tons of structural steel in each boiler unit