WPS is upgrading the emission control system on the Weston Unit 3 electric generator at the company's Weston Generating Power Plant. The Weston Generating Station site is located on 345 acres in the Village of Kronenwetter and Rothschild in Marathon County in central Wisconsin, about 7 miles south of the City of Wausau. The site has two coal-fueled electric generating units.

Nov 2016 - Commercial operation
A major milestone was achieved at Weston Power Plant on Nov. 4, when Unit 3's ReACT (Regenerative Activated Coke Technology) facility went into commercial operation. ReACT is the first air quality control system of its kind in the United States.

"The $345 million project required the focus and dedication of a large team of employees and contractors," said Mark Maurer, manager — major projects for ReACT. "The new equipment is performing well, which is something the whole team should feel proud of."

With ReACT in service, Weston 3's emissions, including mercury (Hg), nitrogen oxides (NOx), particulate matter (pm) and sulfur dioxide (SO₂), are all well below the requirements established in both WPS' Consent Decree and under the Mercury Air Toxics Standard (MATS). While ReACT is now in commercial operation, additional testing is underway, and punch list items are being addressed.

One major advantage of ReACT is that the SO₂ collected by the activated coke is sent to an "acid plant" where it is converted to sulfuric acid and sold to other industries.

"It's excellent that we are not only reducing emissions, but are able to provide a saleable byproduct to support the investment," said Maurer.

The company broke ground on the project in October 2013 following project approval in April 2013 by a unanimous vote by the Public Service Commission of Wisconsin who granted approval to install the new, multi-pollutant control system.

The new system, called ReACT (Regenerative Activated Coke Technology) will significantly reduce sulfur dioxide (SO₂) nitrogen oxides (NOx), mercury (Hg) and other emissions from the exhaust flow.

The new system is in addition to the existing exhaust controls of the Weston 3 fabric filter (bag house installed in 2000), the low NOx burners and separated over-fire air system (installed in 2009) and the mercury control system (installed 2009).

The 321-megawatt Unit 3 electric generator began operation in 1981 and is fueled by Powder River Basin (low sulfur) coal from Wyoming.

Historical results of using this technology at other similar units like Weston 3, showed greater than 90% of SO₂, 90% of mercury, and 20% of NOx being removed from the exhaust stream before going out the stack and into the air.

The system uses activated coke pellets on a slow moving conveyor system and as the boiler's exhaust passes over the conveyor system, the SO₂, NOx and mercury attaches and is adsorbed into the pellets. The pellets are then collected, heated and the pollutants are then broken down and isolated in a by-product recovery system, where they are treated and kept for potential beneficial reuse.

Before and after

Hover over the image below for a before and after artist rendering of the emission control system upgrade.

Before and after

Contract project partnerships

WPS and Hamon Research-Cottrell (HRC) will design, construct and install the new, multi-pollutant control system at Weston Unit 3 using Regenerative Activated Coke Technology, or ReACT™. URS Corporation (acquired by AECOM) was selected to support WPS by providing additional engineering and the site construction management team.

Hamon Research-Cottrell
Hamon Research-Cottrell is a leading provider of air pollution control technology in the United States, having been active for many years in the supply and installation of systems for control of particulate and acid gas emissions. Hamon Research-Cottrell is part of the Hamon Group of companies, headquartered in Mont-St-Guibert, Belgium and providing environmental and energy related technologies for more than 100 years.
AECOM is a global network of experts working with clients, communities and colleagues to develop and implement innovative solutions to the world’s most complex challenges.

ReACT technology

Regenerative activated coke technology (ReACT) is a dry scrubbing system and involves three stages.

  1. Adsorption stage - The exhaust flue gas comes in contact with a slow moving bed of activated coke pellets on a conveyor system. SO₂, NOx and mercury are adsorbed when coming in contact with the pellets.
  2. Regeneration stage - The activated coke pellets containing the SO₂, NOx and mercury are transferred to a thermal regenerator, where reactions take place and the pollutants are released into a sulfur gas stream.

    This is done in the regenerator vessel by pre-heating, heating and then cooling the pellets. The pellets are returned to the absorption stage. The adsorbed mercury is then collected in the bottom of the vessel.
  3. By-product recovery stage - The sulfur-rich gas containing the SO₂ and NOx flows to an adjacent acid recovery plant where a good quality sulfuric acid is produced, stored and prepared for re-sale.

ReACT history

The concept and technology originated in Germany in the 1950's. Additional development took place in the 1970's. The process was refined and used in Japanese mining in the 1980's and finally developed into a full commercialization effort by the Electric Power Development Company as an advanced multi-pollutant control technology that was an alternative to a wet flue-gas desulfurization process. The ReACT process has been used successfully in Japan and in the U.S. at the North Valmy Station in Nevada, operated by Sierra Pacific Power.

WPS certificate of authority

The application for this project can be found on the Public Service Commission of Wisconsin website. The official docket number is 6690-CE-193.

Contact information

WEC Energy Group