Arizona Electric Power Cooperative, Inc. is the generation utility



Arizona Electric Power Cooperative, Inc. is the generation utility
Arizona Electric Power Cooperative, Inc. is the
generation utility which supplies wholesale electric
energy to six member-owner distribution cooperatives,
and several other utilities in the Southwest.
The AEPCO Board of Directors is comprised of
representatives of member systems. The board meets
monthly at AEPCO’s headquarters offices in Benson,
Arizona Electric Power Cooperative, Inc. (AEPCO) is
headquartered in Benson, AZ. Incorporated in 1961,
it has been a customer-owned utility producing electricity at Apache Generating Station, a power plant in
Cochise County. AEPCO’s Class A member systems
serve 144,000 people living in Arizona and portions of
New Mexico and California. Those electric cooperatives are: Anza Electric in Anza, CA; Graham County
Electric in Pima, AZ; Duncan Valley Electric in
Duncan, AZ; Mohave Electric in Bullhead City, AZ;
Sulphur Springs Valley Electric in Willcox, AZ; and
Trico Electric in Marana, AZ.
AEPCO operates the Apache Generating Station,
located near Cochise, Ariz., about 35 miles southeast
of Benson, on U.S. Highway 191, 10 miles south of
Interstate 10. The plant produces a gross 605 MW of
electric energy.
The Class B membership is available to utilities that
have power purchase contracts with AEPCO for 25
MW or more and with a minimum contract of two
years. Currently AEPCO has no Class B members.
The Class C membership is open to electric cooperatives that have entered into power purchase contracts
in the amount of at least 5 MW with a minimum commitment of two years. Presently AEPCO has no Class
C members.
The Class D membership is open to electric utilities
other than Class A, B, or C with written agreements
for power and/or energy and/or substantial service.
Valley Electric Association, Pahrump, NV is AEPCO’s only Class D member.
There are two coal-fired generating units at the site as
well as one natural gas-fired boiler and four gas turbines. The two-coal fired units can also burn natural
gas, which provides AEPCO with greater flexibility in
the fuel purchasing market. Construction of coal-fired
steam Units No. 2 and No. 3 was completed in 1979
and together these units produce 350 megawatts of
AEPCO is committed to protecting and preserving
the environment. Electrostatic precipitators for fly ash
removal, sulfur dioxide scrubbers, boiler combustion
modifications and a 400 foot chimney help keep the
cooperative in compliance with stringent state and
federal environmental regulations. Air quality is monitored around the clock.
The electrostatic precipitators remove 99.5 percent of
fly ash while the scrubber system removes 85 percent
of the sulfur dioxide by a chemical process that converts the gas to a solid. Fly ash and sulfur dioxide are
two byproducts of burning coal.
Other generating units on the site include steam
Unit No. 1 and gas turbine No. 1 which were commissioned in 1964. There are four gas turbines, and
combined these units contribute 137 MW of the plant
generation capacity.
• Generating capacity: 350 megawatts (net)
• Electrical cable: 3,400,00’ (644 miles)
• Concrete: 43,394 cu. yds. (equivalent to 450
miles of sidewalk)
• Coal storage: 300,000 tons (90 day supply)
ST 1
ST 2
ST 3
GT 1
GT 2
GT 3
GT 4
• Made by General Electric
• Each unit capable of producing 240,000 kilovolt
• Hydrogen cooled windings
• Steam superheated to 1,000 degree F
• 3,600 rpm
• 2,400 PSIG
Chimney (stack)
• Height: 400’
• Diameter: 50’(bottom); 44’(top)
• Interior: two 17’ diameter steel liners
• Composition: 1,900 cu. yds. concrete;
257,000 lbs. reinforcing steel
In Service
71 MW
175 MW
175 MW
10 MW
20 MW
69 MW
38 MW
coal / gas
coal / gas
gas / oil
gas / oil
Total Net Generation = 558 MW
Total Gross Generation = 605 MW
903 lamps/bulbs
288 pounds of non-pcb ballasts
120 tons of used scrap metal
5,400 gallons of oil
90% of fly ash was marketed
AEPCO also currently maintains habitat for Western
Burrowing Owls, a Wildlife Viewing Area and in
2010 implemented a mercury control project.
Cooling Towers
• Height: 60’
• Width: 69’
• Length: 325’
• Each tower has nine 28’ (diameter) fans
individually run on 200 horsepower motors
• Cooling capacity: 117,500 gallons/minute each
• Fuel requirements: up to 98 tons of coal/hour
for each unit
• Steam generation: 1,355,000 lbs./hour at
1,005 degree F
• Pressure: 2,620 PSIG at superheater outlet
• Height: 192’
• Structural steel in each boiler unit: 2,400 tons
• Capacity: remove about 23 tons ash/hour
• Efficiency: 99.5%
• Limestone use: 7,600 lbs./hour
• Efficiency: 85% SO2 removed
• Sludge: 4 tons/hour total
Apache Generating Station
3525 N. U.S. Highway 191
Cochise, Arizona 85606
(520) 384-4256
Headquarters Office
1000 S. Highway 80
P.O. Box 670
Benson, Arizona 85602
(520) 586-3631
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