Emissions Control Technology

How New Technology Leads to Cleaner Coal

We designed the Prairie State Energy Campus with the environment in mind. We use state-of-the-art technology to cut emissions, improve efficiency, and work a whole lot greener. Here are the steps we take to harness the power of cleaner coal.

Process 1: Boiler & Nitrogen Oxide Control

Supercritical power plants are highly efficient, creating more energy per ton of coal used. Within the boiler, low-NOx burners impede the formation of NOx by lowering the temperature of the flame to control the way coal combusts.

Process 2: Turbine & Generator

Turbines consist of fan-type blades attached to a shaft that are rotated by steam from the boiler, converting the kinetic energy of the steam into mechanical energy that is distributed over the grid.

Process 3: Selective Catalytic Reduction (SCR)

An SCR further controls NOx emissions by injecting product into the air stream as it passes over a catalyst, causing the NOx to be converted to nitrogen and water. The SCR also assists with mercury control.

Process 4: Dry Electrostatic Precipitator (ESP)

The dry ESP removes virtually all particulates from the air stream in addition to some mercury. The dry ESP uses electrodes to place an electric charge on the particles, which are captured on an oppositely charged plate. The particles are then shaken from the plates and collected.

Process 5: Sulfur Dioxide (SO2) Scrubber

SO2 is dramatically reduced by “scrubbers,” which inject a limestone and water mixture into the air stream, where it reacts to capture or “scrub” the SO2. Scrubbers also help control mercury.

Process 6: Wet Electrostatic Precipitator (ESP)

The air stream passes through the scrubber into a wet ESP, which will remove fine particulates and other constituents. Wet ESPs use multiple high-voltage fields to attract the particles to an electrode, which is then washed with water to capture the constituents, including some mercury.

Process 7: Cooling Tower

Exhaust steam from the turbines is cooled through condensers and recycled back to the plant boilers for reuse. The condenser’s cooling water is sent to high-efficiency cooling towers, where most of the water is recirculated within the plant system and some exits the towers as water vapor.