Wisconsin Public Service Corp. (WPS) applied May 7 at the Wisconsin Public Service Commission for a Certificate of Authority (CA) to install a multi-pollutant control technology commercially known as ReACT on the coal-fired, 321-MW Unit 3 at the Weston power plant.
The purpose of the ReACT system is to reduce SO2, NOx, mercury and other air pollutant emissions from the unit. The ReACT system at Weston Unit 3 was selected because it meets the following overall objectives:
- Reduce SO2, NOx and mercury emissions in order to comply with current, pending and future environmental regulations including the federal Cross-State Air Pollution Rule (CSAPR) (or a similar replacement regulation) and federal and state mercury rules.
- Achieve sufficient SO2 and NOx reductions to meet the emission limitations likely to result from a resolution of the U.S. Environmental Protection Agency’s Notice of Violation (NOV) alleging violations of New Source Review (NSR) and Prevention of Significant Deterioration (PSD) regulations at the Weston plant.
- Allow beneficial use of by-products from emission control systems to the extent practicable.
- Constitutes an economic alternative to replacement of Weston Unit 3.
- Minimize increased emissions of any other regulated pollutants.
- Minimize the adverse impact on Weston Unit 3 balance of plant (BOP) operations during construction.
- Provide long-term reliability, operability, and maintainability for the ReACT equipment.
The Weston plant is located in Marathon County, approximately 7 miles south of Wausau. The site currently has four coal units, two gas/oil-fired combustion turbine generators, and auxiliary equipment such as substations and fuel supply systems. Weston Unit 3 is WPS’s second newest and second largest coal-fired facility. The unit went into service in 1981 and has a heat rating of 3,423.48 mmBtu/hr and burns primarily Powder River Basin (PRB) coal.
Of all of the units in WPS’s fleet, Weston Unit 3 is the first choice to install additional controls. Pulliam Units 5-8 and Weston 1-2 are older, smaller and less efficient units than Weston 3. Installation of the ReACT technology at Weston 3 would free up annual SO2, annual NOx, and ozone season NOx allowances that WPS could use for compliance at other units.
ReACT relies on activated coke that can be re-used
ReACT is an advanced regenerative activated coke (AC) technology that provides for control of SO2 with a coincident reduction of NOx, mercury and other pollutants. The system also produces commercial grade sulfuric acid, a commercially marketable by-product. The ReACT system’s total capital cost estimate, including allowance for funds used during construction (AFUDC), is $288m.
Major construction is currently anticipated to occur to the south and west of the existing Weston Unit 3 fabric filter. The ReACT facilities will be located in open vacant areas to facilitate constructability and reduce relocation and demolition requirements. The fabric filters were installed on Weston Unit 3 in 2000 as part of a separate air pollution control project and will continue in service to support the ReACT system. Low NOx burners and a separated over fire air system were installed for NOx control in 2009. These systems will continue in service to support the ReACT system. A powdered activated carbon injection system (ACI) was installed on Weston Unit 3 in late 2009 for mercury emissions control. This system is expected to be available to provide operational flexibility to meet current and future emissions control requirements.
The ReACT process operates in three stages: adsorption, regeneration, and by-product recovery. The AC material provides a large surface area that is adsorptive, catalytic, and reactive for adsorption of SO2, mercury and other gas species and for the reduction of NOx. After the adsorption step, the AC is thermally regenerated for return to the adsorbers. The AC adsorbent material is in pellet form which has mechanical strength such that the material can be subjected to repeated regeneration cycles. The by-product of the regeneration process is a sulfur-rich gas (SRG) that will be converted into a marketable grade of sulfuric acid.
WPS plans to be in the regulatory approval process for this project at the PSC until January 2013. It plans to award various contracts, including systems and balance of plant design contracts, in February 2013. The new system is due for commissioning in the second quarter of 2016, with commercial operation in the fourth quarter of that year.
Technology is new to the U.S., but not new
WPS, a subsidiary of Integrys Energy Group (NYSE: TEG), said in a May 7 announcement it expects that, based on historical data, the project will reduce plant SO2 emissions by more than 90%, mercury by 90% or more, and NOx by more than 20%.
“We’ve decided to upgrade Weston 3 (W3) to ensure its viability as an electric generator in a climate of future uncertainty regarding environmental regulations,” said Howard Giesler, Weston General Manager. “Adding this new, but proven, technology will position the unit to be in compliance with future EPA regulations, while enabling the production of safe, clean, reliable and economical electricity.”
This new technology simultaneously controls multiple pollutants using only a fraction of the water that conventional wet scrubbers demand, while producing a saleable sulfuric acid by-product commonly used in the fertilizer, papermaking and other industries. A recent license agreement brings this technology to North America. WPS has partnered with Hamon Research-Cottrell Inc. (HRC) to provide the ReACT technology, engineering, erection, and other services for the project. HRC holds the license for the ReACT technology and provides innovative clean air technologies to a wide array of industries including power generation.
“We are grateful to partner with WPS to bring this proven state-of-the-art, multi-pollutant control technology to North America. The innovation WPS has shown in choosing this technology ensuring we maintain our world leadership in clean coal implementation should be applauded by all in the industry” said Bill Dillon, CEO of Hamon Corp.
The ReACT project at Weston will be the first commercial application of this technology in the United States, although it has been used successfully in Japan for many years and has been successfully demonstrated in the U.S. over a period of five months as part of an Electric Power Research Institute project hosted by Sierra Pacific Power at its North Valmy station.
Various parties target Weston emissions
Said the Integrys Form 10-Q filing of May 3 about air issues at two coal plants: “In November 2009, the EPA issued a Notice of Violation (NOV) to WPS alleging violations of the CAA’s New Source Review requirements relating to certain projects completed at the Weston and Pulliam plants from 1994 to 2009. WPS continues to meet with the EPA and exchange proposals on a possible resolution. We are currently unable to estimate the possible loss or range of loss related to this matter.”
The Form 10-Q added: “In May 2010, WPS received from the Sierra Club a Notice of Intent (NOI) to file a civil lawsuit based on allegations that WPS violated the CAA at the Weston and Pulliam plants. WPS entered into a Standstill Agreement with the Sierra Club by which the parties agreed to negotiate as part of the EPA NOV process, rather than litigate. WPS is working on a possible resolution with the Sierra Club and the EPA.”
Also, in November 2010, the Wisconsin Department of Natural Resources (WDNR) provided a draft revised permit for Weston. WPS objected to proposed changes in mercury limits and requirements on the boilers as beyond the authority of the WDNR. WPS and the WDNR continue to meet to resolve these issues. In September 2011, the WDNR issued a draft revised permit and a request for public comments. WPS filed comments objecting to certain provisions in the draft permit. “We do not expect this matter to have a material impact on our financial statements,” the Form 10-Q noted.
Also, since 2008, WPS received four NOVs from the WDNR alleging various violations of the different air permits for the entire Weston plant, Weston 4, Weston 1, and Weston 2, as well as one NOV for a clerical error involving pages missing from a quarterly report for Weston. Corrective actions have been taken for the events in the five NOVs. In December 2011, the WDNR dismissed two of the NOVs and referred the other three NOVs to the state Justice Department for enforcement. “We do not expect this matter to have a material impact on our financial statements,” the Form 10-Q again added.
Weston 3 project part of overall compliance planning
In order to assess specific compliance options for Weston Unit 3 a CSAPR compliance plan for Pulliam and Weston Units 1-2 needed to be developed, said the company’s filing with the Wisconsin PSC. The planning analysis summary shows:
- Continuing to operate Weston Units 1-2 and Pulliam Units 5-6 as coal-fired units results in WPS not complying with CSAPR in the long term and the present value revenue requirement savings associated with continued operation on coal will not support capital investments needed to maintain compliance.
- Converting Weston Units 1-2 and Pulliam Units 5-6 to natural gas operation results in reduced SO2 and NOx emissions and is a cost effective compliance option due to the value of generating capacity in the 2014–2022 timeframe.
- Continuing to operate Pulliam Units 7-8 as coal-fired units with a $79m capital investment in dry sorbent injection (DSI), fabric filter and cooling tower to assure compliance results in cost effective compliance (when risk is taken into account) with CSAPR. Continued operation of Pulliam Units 7-8 as coal-fuelled units also helps to allow the continued operation of Pulliam Units 5-6 on natural gas due to staffing levels for Pulliam Units 7-8.
- Continuing to operate Pulliam Units 5-6 on natural gas and Pulliam Units 7-8 as coal-fuelled units provides approximately 333 MW of capacity during a time when capacity is expected to be scarce and expensive.
The Reference Plan consists of converting Weston Units 1-2 and Pulliam Units 5-6 to natural gas operation while continuing to invest in environmental controls for Pulliam Units 7-8 so that those units can continue to operate as coal-fuelled units. Due to the uncertainty related to the gas pipeline system serving the Weston site, it may not be cost effective to convert Weston Units 1-2 to natural gas. This uncertainty was addressed by evaluating the economics associated with Weston Unit 3 compliance (replacement versus emission controls) assuming Weston Units 1-2 converted to natural gas versus Weston Units 1-2 being retired after 2014.
There are three compliance options for Weston Unit 3 that will assure compliance with Phase 2 of CSAPR. These options are also expected to meet the likely emission limits resulting from a resolution of the EPA NOV.
- Retire Weston Unit 3 after December 2016, the base case assumption.
- Install ReACT on Weston Unit 3 by December 2016.
- Install a dry flue gas desulfurization/selective catalytic reduction combo on Weston Unit 3 by December 2016.