Trimble County Generating Station

Trimble County Generating Station is situated on more than 2,200 acres in a rural setting along the Ohio River in Trimble County — near Bedford, Ky. — 50 miles northeast of Louisville.  The plant’s generating assets currently consist of TC1, a pulverized-coal-fired unit with a net rated capacity of 514 megawatts; TC2, a pulverized-coal-fired unit with a net rated capacity of 760 megawatts; and TC5 through TC10, which are natural gas-fired, simple cycle combustion turbines — each with a nominal rating of 160 megawatts.  TC1, LG&E and KU’s lowest cost coal-fired generating unit, went into commercial operation in December 1990. It is operated predominantly in a base-load mode. TC2 began commercial operation in January 2011 and is a supercritical boiler unit. Combustion turbine units TC5 and TC6 went into commercial operation in May 2002; TC7 through TC10 began commercial operation in July 2004.  The combustion turbines are predominantly operated during times of peak demand because it is not only most cost-effective, but also because the CTs can be started and ramped-up quickly to meet demand spikes and take advantage of transient market conditions.  The same plant operating and maintenance personnel support both the coal-fired and combustion turbine sites. Unlike LG&E and KU’s other generating assets, which are wholly owned by LG&E and KU, TC1 and TC2 are owned in partnership with the Illinois Municipal Electric Agency and the Indiana Municipal Power Agency. IMEA and IMPA share a 25-percent ownership interest in both units, as well as in the assets supporting the operation of the coal-fired plant.

Environmentally-responsible power generation

Trimble County Station is one of the most environmentally and technologically advanced coal-fired generating plants in the U.S. TC1, which burns high-sulfur bituminous coal, is equipped with low-NOx (nitrogen oxide) burners and selective catalytic reduction (SCR) equipment, which reduce NOx emissions by more than 90 percent. A dry electrostatic precipitator (DESP), reduces particulate emissions by more than 98 percent.  A hydrated lime injection system reduces sulfur trioxide (S03) emissions to less than five parts per million. And a wet limestone flue gas desulfurization (FGD) unit reduces sulfur dioxide (S02) emissions by more than 98 percent. In addition to the environmental control equipment installed on TC1, TC2 has been equipped with a carbon injection/baghouse system to reduce mercury emissions, and a wet electrostatic precipitator (WESP) for small particulate and acid mist emission reduction. TC2 was designed to burn a blend of high-sulfur bituminous coal and low-sulfur sub-bituminous Powder River Basin coal.  Trimble County Station is a near-zero-discharge plant site, meaning there are only two discharges from the site which are strictly monitored and controlled. Aside from surface water runoff (rainfall) and cooling tower blow-down — which each have controlled, permitted discharges to the Ohio River — all combustion process constituents and by-products either remain on-site or are transported off-site for beneficial re-use.  Fly ash is used as concrete filler and in the manufacturing of ceramic tile. Synthetic gypsum is an FGD by-product used in manufacturing wallboard; and bottom ash is used to produce blasting grit and in manufacturing roofing shingles.  The plant site also has its own wildlife preserve. The company permanently dedicated 114 acres to the preserve, which includes wetlands and forest areas. Many forms of wildlife inhabit the plant site. In addition to nesting pairs of American bald eagles and peregrine falcons, other animals — such as fox, deer and wild turkeys — have grown accustomed to the plant’s presence and are routinely seen on the site.

Materials delivery

There is no rail delivery service to Trimble County Station. The plant’s two barge unloading systems supply limestone — FGD reactant — and coal to the plant via separate conveyor systems.  Coal and limestone are received in 1,500-ton barges and carried nearly a half-mile from the Ohio River to the plant. Approximately 1.7 million tons of coal and 180,000 tons of limestone are consumed by TC1 annually. A six-mile-long natural gas pipeline transports more than two billion cubic feet of natural gas that is consumed by the six combustion turbines annually. Other raw materials, parts and equipment are brought in by truck.

New technology; new construction

TC2 was built adjacent to TC1. The $1.2 billion unit features modern, thermally efficient and advanced environmental technology. TC2 is the cleanest, most efficient coal-fired unit in Kentucky and one of the cleanest, most efficient in the United States. This project received a $125 million tax credit from the U.S. Department of Energy for its use of advanced clean coal technology. The entire benefit of this tax credit was passed to customers by reducing the cost of construction of TC2.  Additionally, more than $50 million was invested in new coal-blending, limestone- and coal-handling system upgrades, improvements to the existing station boiler water treatment systems and a new auxiliary boiler to replace the three existing auxiliary boilers.