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Thomas Hill Energy Center

Thomas Hill Energy Center on a sunny winter afternoon.
Thomas Hill Energy Center

Thomas Hill balances affordability, reliability with clean environment

Associated Electric employs about 215 people at Thomas Hill Energy Center, which is an important resource for providing members reliable, around-the-clock electricity at an affordable cost. The plant also has received national recognition for its efficiency and successful conversion to low-sulfur coal that reduced sulfur dioxide emissions 90 percent.

The cooperative then achieved a systemwide nitrogen oxides emission rate reduction of up to 90 percent through its $423 million environmental controls project at Thomas Hill to meet new air quality requirements.

Associated Electric was first to reduce mercury emissions up to 80 percent with use of CyClean refined coal in cyclone units 1 and 2. The cooperative added a refined coal system on Unit 3 to further reduce mercury emissions in 2015. Using refined coal is part of Associated Electric’s compliance with the Environmental Protection Agency’s Mercury and Air Toxics Standards.

Thomas Hill Lake was built to help cool equipment at the power plant, which uses 576 million gallons a day, enough to fill 872 Olympic-size swimming pools. After use, nearly all of the water travels two miles through canals to cool down before entering back into the 1.5 billion gallon lake. The public benefits too. Swimming, fishing and boating are popular on the lake, which also serves as a 5,000-acre wildlife habitat managed by the Missouri Department of Conservation under an agreement with Associated.

Associated Electric recycles fly ash, a byproduct of coal combustion, from its Thomas Hill Energy Center. The fly ash is extremely fine and has a calcium content of 20 percent or more, which makes it a good substitute for cement in making concrete or as a soil stabilizer.

Recycling fly ash provides a product to industries, produces revenue that helps Associated Electric keep its cost to members low and saves landfill space and transportation costs.

Quick facts

Three generating units:

Unit 1 – Constructed 1966
General Electric turbine
Net capacity is 180 megawatts

Unit 2 – Constructed 1969
Westinghouse turbine
Net capacity is 303 megawatts.

Unit 3 – Constructed 1982
Westinghouse turbine
Net capacity is 670 megawatts.


We CARE about the environment and constantly seek ways to improve the efficiency and environmental performance of our units.

In fact, we have invested millions of dollars to improve air quality, reducing nitrogen oxides, sulfur dioxide and mercury emissions.

Powerful career opportunities

Join the team that powers up Missouri, Oklahoma and Iowa.