Weston 3 Environmental Upgrade Project
Project Description
Upgrade the existing emissions control equipment at the 25-year-old Wisconsin Public Service Weston 3 power plant. The project will install additional equipment to reduce sulfur dioxide (S02), nitrogen oxide (NOx) and mercury (Hg) air emissions. View News Release for further details.
Project Purpose
The U.S. Environmental Protection Agency (EPA) passed two regulations in March 2005 requiring increased control of sulfur dioxide (SO2) and nitrogen oxide (NOx) and new requirements for measurement and control of mercury (Hg) produced by electric generating units. The new EPA emissions program requirements are to be phased in from 2009 to 2018.
The 25-year-old Weston 3 power plant will
update its emission control equipment.
(Photo April 2002)
EPA Emissions Program
The sulfur dioxide and nitrogen oxide guidelines are defined in the Clean Air Interstate Rule (CAIR) announced on March 10, 2005.
The mercury guidelines are defined in the Clean Air Mercury Rule (CAMR) issued March 15, 2005.
Both will be implemented in two-phases:
- CAIR-Phase One: NOx reduced by 50 % in 2009. SO2 reduced by 50 % in 2010.
- CAIR-Phase Two: NOx reduced by 65% in 2015. SO2 reduced by 65 % in 2015.
(CAIR compliance initial cost estimates are $250 million.)
- CAMR-Phase One: 2010 to 2017, mercury reduced by 21%.
- CAMR-Phase Two: In 2018, mercury reduced by 70 %.
(CAMR compliance initial cost estimates are $120 million.)
Emission Explanation
- Nitrogen Oxide (NOx) contributes to smog, ozone and fine particulates.
- Sulfur Dioxide (SO2) contributes to acid rain and fine particulates.
- Mercury (Hg) released into the air can find its way to ground water. Certain microorganisms can change it into methyl mercury, a toxin that can build up in fish, and then enter the food chain.
Anticipated Project Results
- Sulfur dioxide (SO2) to be reduced by about 8,700 tons per year.
- Mercury (Hg) to be reduced by about 78 pounds per year.
- Nitrogen oxide (NOx) emission rate to be reduced by an additional 40% of current levels.
Background
The 338-megawatt Weston Unit 3 power plant is now 26 years old. It is located along the Wisconsin River seven miles south of the city of Wausau in Marathon County, Wisconsin. It is located on 450 acres of land in the Villages of Kronenwetter and Rothschild. Weston Unit 3 is part of the Weston Generating Station that features three base-load operating units and one 500-megawatt power plant under construction. Weston 1 (1954) is 60-megawatts, Weston 2 (1960) is 75-megawatts and Weston 3 (1981) is 338 megawatts. Weston 4 (operational in 2008) will be 500-megawatts. All Weston plants use low-sulfur coal.
The 338-megawatt Weston 3 power plant has been
the backbone of the electric system
in central
Wisconsin since 1981. (Photo April 2002)
Equipment Description
To capture sulfur dioxide (SO2) and mercury (Hg), a Flue Gas Desulfurization System (FGD), or scrubber, will be installed. The scrubber removes sulfur dioxide by injecting a mixture of limestone and water into the flue gas stream. This project was originally announced in December 2006 and has been on delay since June 2007. The project original in service date was 2010 but has been delayed to 2013. Constrained market conditions, particularly for specialty metals and equipment used to manufacture the retrofit equipment has increased dramatically. Original cost estimates were $110-million (December 2006) and are now $180-million (June 2007).
To capture nitrogen oxide (NOx), a combustion modification will be made to the existing Weston 3 boiler called "Separated Over-Fire Air." This project was announced on June 1, 2005 and has an in service date of fall of 2008.
Links
- To access an electronic copy of the Wisconsin Public Service Construction
Authorization (CA) of the Weston 3 Retrofit project, log on to:
http://psc.wi.gov/apps/erf_search/default.aspx.
The official Public Service Commission of Wisconsin (PSCW) Utility/Docket number for this project is 6690-CE-193. - For more information on the Environmental Protection Agencies ruling on the Clean Air Interstate Rules, log on: http://www.epa.gov/cair/
- For more information on the Environmental Protection Agencies ruling on the Clean Air Mercury Rules, log on: http://www.epa.gov/air/mercuryrule/
- For more information on Wisconsin's Clean Air Interstate Rules interpretation, log on: http://dnr.wi.gov/air/pdf/caatf061215cairupdate.pdf
- For more information on Wisconsin's Clean Air Mercury Rules interpretation, log on: http://dnr.wi.gov/air/toxics/mercury/index.htm