Indianapolis Power & Light on May 31 petitioned the Indiana Utility Regulatory Commission for approval of environmental compliance projects and related issuance of certificates of public convenience and necessity for its coal-fired Petersburg Generating Station.
The application covers costs to be incurred in two areas at Petersburg:
- compliance with the federal National Ambient Air Quality Standards (NAAQS) for SO2; and
- the disposal of Coal Combustion Residuals (CCR).
IPL’s largest generating station is the four-unit, coal-fired, 1,697-MW Petersburg plant in Petersburg, Indiana. Each of the four Petersburg units is equipped with flue gas desulfurization (FGD) systems. FGD systems (also called “scrubbers”) are utilized to reduce certain regulated emissions that would otherwise be discharged into the atmosphere. Petersburg Units 3 and 4 operate with wet limestone FGDs that were installed as part of the original equipment which was placed in service in 1977 and 1986 respectively. The FGD technology installed at Petersburg Units 1 and 2 was similar to the existing FGD systems on Petersburg Units 3 and 4.
In June 2010, EPA revised the NAAQS for SO2 from 140 parts per billion (ppb) on a 24-hour basis to 75 ppb on a one-hour basis. In September 2015, the Indiana Department of Environmental Management (IDEM) published air regulation revisions to address the 2010 SO2 NAAQS by establishing new and more stringent emission limits for the Petersburg generating units. IPL is required to comply with the new and more stringent emission limits to address the revised NAAQS for SO2 beginning on Jan. 1, 2017. Specifically, the 30-day rolling average emission limits will be significantly decreased.
On April 17, 2015, the U.S. EPA published the final CCR Rule, which regulates CCR as non-hazardous waste under Subtitle D of the Resource Conservation and Recovery Act (RCRA). The CCR Rule became effective on Oct. 19, 2015. The CCR Rule establishes national minimum criteria for existing CCR surface impoundments (ash ponds), including location restrictions, structural integrity, design and operating criteria, groundwater monitoring and corrective action, closure requirements and post closure care. Failure to demonstrate compliance with the national minimum criteria results in the requirement to close existing active ponds within five years, with some potential for extensions, as needed.
EPA published the final revisions to the Effluent Limitation Guidelines (ELG) for Steam Electric Generating Stations on Nov. 3, 2015. The revised ELG regulations require dry fly ash handling, dry or closed loop bottom ash handling, and apply numerical limits on FGD wastewater.
IPL will comply with the dry fly ash handling and limits on FGD wastewater as a result of an NPDES wastewater treatment project approved by the commission in a prior case. In addition, the ELG will require dry bottom ash handling at Petersburg with compliance required as soon as possible beginning Nov. 1, 2018, but no later than Dec. 31, 2023. Petersburg will comply with this ELG requirement as a result of the CCR Compliance Project for which approval is sought in this May 31 petition.
The NAAQS Compliance Project includes the construction, installation and use of control measures and the implementation of changes to the operation and maintenance of the Petersburg units, to enhance the integrity and reliability of the existing FGD systems. More specifically, the NAAQS Compliance Project includes the following control measures:
- Units 1-4 dibasic acid (DBA) System
- Units 1 & 2 Recycle Pump Vibration Monitors
- Unit 3 Backup Recycle Pumps
- Unit 2 Switchgear
- Emergency Limestone Conveyance
- Emergency Ball Mill
- Limestone Conveyor Fire Suppression
- Unit 4 Backup Dewatering Filter
- DBA Impact on NPDES
To comply with the CCR bottom ash requirement, IPL proposes to construct, install and commission a closed loop bottom ash dewatering system at Petersburg.
Petersburg is the last, best coal hope at this utility
Bradley D. Scott, employed by AES US Services LLC and the Senior Vice President of Power Supply for Indianapolis Power & Light, said in May 31 supporting testimony: “IPL’s fleet is changing dramatically. IPL’s request to construct a new Combined Cycle Gas Turbine (‘CCGT’) at the Eagle Valley Station and to refuel Harding Street Station Units 5 and 6 (‘HS-5’ and ‘HS-6’) from coal to natural gas was approved in IURC Cause No. 44339. The HS-5 and HS-6 refueling has been completed and the Units have been returned to service and are providing generation service to IPL’s customers.
“Harding Street Station Unit 7 (‘HS-7’) has ceased using coal as a fuel and has been refueled to natural gas as approved in IURC Cause No. 44540. The new CCGT is expected to be in-service in April 2017. The existing diesel generator and coal-fired Units at Eagle Valley were retired in April 2016.
“Upon completion of the gas conversion of the Harding Street Units, IPL has total owned electric generating capacity of approximately 2,832 Net MWs (summer rating for planning purposes). Upon completion of the Eagle Valley CCGT, IPL will have a total owned electric generating capacity of approximately 3,503 Net MWs (summer rating for planning purposes). The generation capacity is located at four primary sites: Georgetown (Northwest Indianapolis), Harding Street Station (Southwest Indianapolis), Eagle Valley Station (Martinsville, IN) and Petersburg Station (Petersburg, IN).
“IPL secured energy purchases from approximately 300 MW of wind generation located in Indiana and Minnesota and approximately 95 MW of energy from solar facilities located throughout its service territory under long term Power Purchase Agreements (‘PPA’) approved by the Commission.”
IPL is an indirect subsidiary of AES Corp. (NYSE: AES).
Scott noted that even with the proposed control measures, the Petersburg coal units are expected to produce less electricity due to the more stringent NAAQS SO2 limits. The NAAQS Compliance Project, however, will allow the units to run at a higher availability than without the compliance measures. They would still be able to burn Illinois Basin coal, he said. That kind of coal is generally higher in sulfur than other coals.
He added about project timing: “The DBA System, which has the largest impact on the ability to consistently meet the new SO2 limits, is currently scheduled to be in service by January 1, 2017 which is when the new limits are in effect. The other equipment components are longer lead time items (switchgear/transformer and ball mill) or require a longer construction timeline (limestone conveyance and fire suppression) and are proposed to enhance the ongoing reliability of the FGDs. These reliability items are estimated to go into service throughout 2017 with all work completed by January 1, 2018.”