In 2000, We Energies announced our Power the Future (PTF) plan which includes investing in advanced power generation, adding renewable energy resources and improving existing power plants. Because of the complexity and significant financial investment in these major initiatives, our plan has been implemented over several stages.

We Energies has a long standing commitment to environmental performance. Since the late 1980s, we have shown a steady reduction of sulfur dioxide (SO2), nitrogen oxide (NOx) and particulate emissions. As emission control technology has advanced, We Energies has been actively implementing new equipment at its generation facilities to meet new state and federal air quality requirements while maintaining system reliability and cost-effectiveness.

With energy use continuing to grow, our existing generating units remain critical to our ability to supply the needed energy at a reasonable price. By implementing additional environmental controls to our existing generating facilities, we will continue to meet the growing energy needs as well as improve air quality in the most cost-effective means for our customers and the state of Wisconsin.

Pleasant Prairie Power Plant
As part of our commitment to upgrade the environmental performance of our existing facilities, a new state-of-the-art Air Quality Control System (AQCS) was added to the Pleasant Prairie Power Plant. A selective catalytic reduction system was put in place to reduce emissions of NOx, and a flue gas desulfurization system was constructed to reduce SO2. Both of the Pleasant Prairie units are now operating with these state-of-the-art controls in place. Read more about this project.

Oak Creek Power Plant
A new AQCS is being constructed at the Oak Creek Power Plant to further reduce SO2 and NOx emissions. The new system will cut SO2 emissions by 80-90 percent and NOx emissions by 60-70 percent. The project will play a significant role in improving the air quality in southeastern Wisconsin.

This project is anticipated to save our customers more than $600 million compared to premature retirement of the units, and remains the most prudent and cost-effective way to meet the needed energy demand while providing environmental benefit to our region. Read more about this project.

How We Produce Electricity While Reducing Emissions
The process of generating electricity occurs in several steps. First, coal is burned in a large boiler to make high-pressure, high-temperature steam. A turbine converts the thermal energy in the steam to mechanical energy. The spinning turbine then drives the generator to produce electricity.

Specialized equipment is used at different points throughout the generation process to remove emissions from the units. The first step in reducing emissions occurs by utilizing a low NOx burner to burn the coal. This equipment regulates the rate of combustion of the coal by controlling the amount of air available at different elevations within the boiler to complete the combustion. This results in lower NOx emissions.

After exiting the boiler, the flue gas goes through an electrostatic precipitator (ESP). In the ESP, a series of positively charged collection plates, remove negatively charged particulate matter from the flue gas. The ESP captures more than ­­99 percent of the particulate matter in the flue gas.

Next, the wet flue gas desulfurization (FGD) system, also known as the wet FGD or “scrubber,” is used to control SO2 and hydrogen chloride, as well as other water-soluble emissions. As the flue gas passes through the scrubber, it is mixed with limestone slurry. The limestone reacts with the flue gas and absorbs the sulfur dioxide in the flue gas, forming calcium sulfite. Air (oxygen) is blown into the absorber tank causing a chemical reaction which converts the calcium sulfite into calcium sulfate or synthetic gypsum. The gypsum slurry is then dewatered and can be used as a valuable product to make wallboard for construction projects.

To reduce NOx emissions even further, a selective catalytic reduction system (SCR) is employed. Within this system, an ammonia solution is injected into the flue gas stream. The NOx in the flue gas reacts with the injected ammonia, in the presence of a catalyst, producing nitrogen and water vapor.