The Indiana Department of Environmental Management (IDEM) is taking public comment until May 3 on a draft air permit covering activated carbon injection installations on the coal-fired units of the Petersburg power plant.
Indianapolis Power & Light is pursuing a significant modification of its Part 70 Operating Permit issued in October 2006. Under this permitting, the following emission units would be approved for construction:
- One activated carbon injection silo, serving unit 1, identified as ACI-1, planned to be constructed in 2013, with a maximum storage capacity of 160 tons, and a maximum throughput of 650 lbs/hr, controlled by a bin vent filter.
- One activated carbon injection silo, serving unit 2, identified as ACI-2, planned to be constructed in 2014, with a maximum storage capacity of 230 tons, and a maximum throughput of 1,225 lbs/hr, controlled by a bin vent filter.
- One activated carbon injection silo, serving unit 3, identified as ACI-3, planned to be constructed in 2014, with a maximum storage capacity of 275 tons, and a maximum throughput of 1,637 lbs/hr, controlled by a bin vent filter.
- One activated carbon injection silo, serving unit 4, identified as ACI-4, planned to be constructed in 2014, with a maximum storage capacity of 275 tons, and a maximum throughput of 1,640 lbs/hr, controlled by a bin vent filter.
The Petersburg plant’s coal units are:
- One coal/No. 2 fuel oil fired boiler, identified as Unit 1, constructed prior to 1967, with a design capacity of 2200 MMBtu per hour. Unit 1 uses an electrostatic precipitator and FGD scrubber (installed in 1996), and low NOX burners (installed in 1995) for NOX reduction.
- One coal/No. 2 fuel oil fired boiler, identified as Unit 2, constructed prior to 1969, with a design capacity of 4144 MMBtu per hour. Unit 2 uses an electrostatic precipitator, FGD scrubber (installed in 1996), selective catalytic reduction (installed in 2004) and low NOX burners.
- One coal/No. 2 fuel oil fired boiler, identified as Unit 3, constructed prior to 1977, with a design capacity of 5540 MMBtu per hour. Unit 3 uses an electrostatic precipitator, selective catalytic reduction (installed in 2004) and an FGD scrubber.
- One coal/No. 2 fuel oil fired boiler, identified as Unit 4, which began operation in 1986, with a design capacity of 5550 MMBtu per hour. Unit 4 uses an electrostatic precipitator, FGD scrubber and low NOX burners (installed in 2001).
These are among several air projects planned for IPL coal units
IPL, a unit of AES Corp. (NYSE: AES), filed detailed testimony on these and other planned air projects in September 2012 at the Indiana Utility Regulatory Commission. IPL has settled issues in that case with parties but the docket was still open as of April 9.
The summer-rated capacity of the Petersburg units is 1,752 MW and it is 427 MW for Harding Street Unit 7. IPL said these new emissions controls are needed to comply with various environmental regulations, including the Mercury and Air Toxics Standards (MATS). IPL wants to:
- install and operate a Pulse Air Fabric Filter System (baghouse) on Units 2 and 3 at Petersburg;
- upgrade the electrostatic precipitators on Unit 7 at Harding Street and Petersburg Units 1, 3 and 4; and
- install other environmental controls and monitoring equipment including activated carbon injection (ACI), sorbent injection (SI), flue gas desulfurization (FGD) system upgrades and continuous emission monitoring (CEMS) equipment.
James Ayers, IPL’s Director of Corporate Planning and Analysis, said in opening testimony that IPL has four generating stations, three of which encompass eleven coal-fired units that fall under the Mercury and Air Toxcs Standards (MATS). This includes five larger scrubbed units (the Big Five) – Petersburg Units 1-4 and Harding Street Unit 7 (HS Unit 7). There are also six smaller unscrubbed units (the “Small Six”) – two at Harding Street and four at Eagle Valley. All of IPL’s coal-fired units must comply with the MATS rule, be converted to natural gas, or retired.
The Small Six are the oldest, smallest, least efficient, and highest cost units in IPL’s fleet. The Big Five on the other hand are IPL’s largest, youngest, and most efficient units. Together, they comprise 2,179 MW of baseload generation. They have all been fully scrubbed for SO2, three have selective catalytic reduction (SCR) technology to control NOx and have been identified as the long term baseload core of IPL’s generating fleet. In addition, these controls also assist in the removal of MATS-regulated emissions – including acid gases (HCl), mercury (Hg) and particular matter (PM).
The four Petersburg units and Harding Street Unit 7 all average well over 70% capacity factors and are expected to remain high utilization generating assets. Recently, with natural gas prices forecast to remain low relative to historic levels and other forms of fossil generation, comparisons to efficient gas-fired generation (combined-cycle gas turbine or CCGT) can also make sense, Ayers wrote.
The dispatch costs of the Big Five units will increase due to these new controls. “However, with the identified MATS control plan, the Big Five Units will continue to burn lower cost high sulfur (and unconstrained Hg) coal in close proximity to the plant keeping dispatch costs lower,” Ayers added. “Thus dispatch costs will not be increased for any coal sourcing restrictions.”