Georgia Power able to bag some of its baghouse projects for coal plants

As it refined the technology and compliance options – and got a break from the U.S. Environmental Protection Agency – Georgia Power backed out some of the baghouse controls that it had previously planned to install on some of the coal-fired capacity it planned to extend the life of.

Georgia Power and Southern Co. Services officials prepared combined testimony outlining this evolution that was filed March 19 at the Georgia Public Service Commission in support of a 2013 integrated resource plan (IRP) that was filed in January at the Georgia Public Service Commission. The participating officials were: Kyle Leach, Director of Resource Policy and Planning for Georgia Power; Garey Rozier, Manager of Resource Planning for Southern Co. Services; and Larry Legg, Manager of Market Planning for Georgia Power.

They noted that the commission previously approved the company’s expenditures associated with the initiation of construction of baghouses for Plant Bowen Units 1–4, Plant Wansley Units 1-2, and Plant Hammond Units 1–4. The commission in that same decision also certified three power purchase agreements (PPAs), and decertified Plant Branch Units 1-2 and Plant Mitchell Unit 4C.

Since then, Georgia Power has continued to evaluate the requirements of the EPA’s final Mercury and Air Toxics Standards (MATS) rule and the overall compliance strategy on a unit-by-unit basis, relying on Georgia Power’s and parent Southern Co.’s (NYSE: SO) extensive research and development expertise. Now that the company has had the opportunity to further analyze and assess the impact of the final MATS rule, a significant portion of the uncertainty that framed the discussion in a 2011 IRP Update has been eliminated.

As a result of its analysis, Georgia Power determined, and has previously notified the commission, that only Plant Bowen Units 3 and 4 need baghouses at this time and that MATS compliance can be achieved at Plant Bowen Units 1-2, Plant Wansley Units 1-2 and Plant Hammond Units 1–4 by installing activated carbon and hydrated lime injection systems and performing precipitator work. Activated carbon and hydrated lime injection systems will also be added to Plant Bowen Units 3-4 for mercury control. All units at Bowen, Hammond and Wansley will install scrubber additive systems. For MATS compliance, every coal-fired power plant in the Georgia Power fleet will have a dedicated system added to control mercury emissions and to ensure MATS compliance.

“Capitalizing on differences between the proposed MATS rule and the final rule, the Company utilized its and Southern Company’s substantial R&D capabilities and technical expertise to develop a solution that resulted in the removal of five baghouses from its compliance strategy,” the officials said. “Chief among the differences in the rule was a change in the particulate matter standard between the proposed and final rules. In the proposed rule, the EPA would have imposed a very stringent and complicated limit on particulate emissions that ultimately would have resulted in a unit-specific limit on particulate matter emissions, thereby removing all compliance margin without accounting for natural variation in the operation of a generating unit. Therefore, the only compliance option under the proposed rule would have been installation of baghouses to attempt to comply under all operating conditions. In the final rule, however, the EPA altered the form of the particulate matter limit such that, while still very stringent, it is a standard limit that applies to all units rather than a unit-specific limit. The limit is also in a form that allows for additional compliance options to be considered and evaluated on a unit-specific basis….”

Other compliance strategies being brought into play

Aside from the coal-fired units for which the company seeks decertification and the environmental controls being added to Plant Bowen Units 1–4, Plant Wansley Units 1-2, and Plant Hammond Units 1–4, additional environmental controls and other changes will be required for some remaining coal-fired units to continue to operate on coal after the MATS compliance date of April 16, 2015.

Specifically:

  • Georgia Power plans to switch Plant McIntosh Unit 1 to operate on low-sulfur, lower-priced Powder River Basin (PRB) coal (pending a successful test burn and further study). If the test burn is deemed successful, Plant McIntosh will also add MATS controls, namely an activated carbon injection (ACI) system for mercury control and a dry sorbent injection (DSI) system to ensure compliance with the MATS acid gases limit.
  • Plant Scherer Units 1-3 will also be retrofitted with additional controls in order to ensure MATS compliance. Although these units will be well controlled due to installation of the required Georgia Multipollutant rule controls, a bromide injection system will be installed in order to most cost-effectively comply with the MATS requirements.

For the other remaining coal-fired units that will continue to operate, Georgia Power has concluded that it is not cost-effective to install the environmental controls necessary to enable these units to remain operational on coal. Instead, the company has found it to be most cost-effective for customers to switch the coal-fired Plant Yates Units 6-7 and Plant Gaston Units 1–4 to natural gas as the primary fuel.

Southern’s R&D work helped define compliance options

The R&D conducted by Georgia Power and Southern Co. concerning emissions control has been directly applicable to the specific technology decisions at Georgia Power plants presented in the 2013 IRP, the officials noted. For example, the research conducted by Southern on mercury and particulate control beginning in the 1990s led to innovations in baghouse design. The knowledge gained from this research led to the development of the Compact Hybrid Particulate Collector (COHPAC) baghouse design that is used at Plant Scherer and will be used at Plant Bowen Units 3 and 4 to achieve MATS compliance. The COHPAC baghouse is now established in the industry as an effective means of improving both particulate control and mercury control and is less costly than traditional baghouses.

Southern R&D activities were also instrumental in helping Georgia Power identify mercury control technologies (a primary component of MATS compliance) that were significantly less costly than baghouse installations. This process began in the early 2000s, when Southern conducted several activated carbon injection studies and discovered that sulfur oxides present in flue gas can interfere with mercury capture by activated carbon. This sulfur chemistry interference is the reason that the use of activated carbon for the control of mercury without a baghouse was widely considered to be infeasible while burning higher sulfur coals.

However, building on Southern’s discovery in the early 2000s, testing at Plants Bowen, Hammond, and Wansley in 2012 led by Southern researchers showed that the careful use of hydrated lime greatly reduced the interference, and that the injection of both activated carbon and hydrated lime into an ESP was a viable option for certain units and less costly than a baghouse. This testing was conducted as part of the initial baghouse work approved by the Georgia commission in the 2011 IRP Update, they added.

Southern has also conducted various investigations of chemical additives to flue gas scrubbers to help retain captured mercury in the scrubber and has studied the use of calcium bromide as a coal additive for increasing mercury capture by scrubbers on low chlorine coals, such as the PRB coal used at Plant Scherer. These additives are incorporated into the company’s compliance strategy for the plants to achieve mercury MATS compliance at the least cost.

Based on the resources assumed in this 2013 IRP, Georgia Power has projected that under a low gas price scenario in 2020, the company could generate up to 50% of its electricity from its natural gas resources (while reducing its coal generation to just 18%). On the other hand, in a high gas price scenario, the company would be able to shift and generate up to 40% of its electricity from coal resources (while reducing natural gas-fired generation to just 28%), Leach wrote.

“Flexibility is critical in light of the various risk factors that could result in higher than forecast natural gas prices, whether over the short- or long-term,” the officials added. “For instance, a temporary but significant interruption in natural gas production could lead to a spike in natural gas prices over the short-term or new regulation of hydraulic fracturing drilling (‘fracking’) could lead to a longer-term increase in natural gas prices. In either case, the Company’s diverse fleet will allow it to shift generation in order to benefit from the lowest cost fuel option. Together, the Company’s nuclear and renewable generating resources account for approximately 30% of the Company’s electricity production.”

Georgia Power to shut down various units, including several coal facilities

The company is requesting decertification of Plant Branch Units 3-4, Plant McManus Units 1-2, Plant Kraft Units 1-4, Plant Yates Units 1-5, Plant Boulevard Units 2-3 and Plant Bowen Unit 6, for a total of 2,093 MW of generating capacity.

Here is an outline of some of the targeted units:

  • Branch Units 3-4 are fired with coal, have a total capacity of 509 MW and 507 MW, respectively, and were placed in service in 1968 and 1969, respectively.
  • Kraft Units 1-4 are coal-fired units that were placed in service at various times between 1958 and 1971 and have a total capacity of 316 MW.
  • McManus Units 1-2 are oil-fired steam facilities that went into service in 1952 and 1959, respectively, and have 43 MW and 79 MW of capacity, respectively.
  • Yates Units 1–5 are coal-fired units that were placed into service at various times between 1950 and 1958 and have 579 MW of total capacity.
  • Boulevard Units 2-3 are oil-fired combustion turbines (CT) rated at a capacity of 14 MW each, and were installed in 1970 along with Unit 1. Both units recently experienced a significant equipment failure and the company’s economic analysis demonstrates that the repairs are not in customers’ best interest. Boulevard Unit 1 is not damaged, remains cost-effective, and is recommended for continued operation.
  • Bowen Unit 6 is a 32-MW oil-fired CT that is only permitted to operate during non-summer months due to ozone nonattainment requirements in the area.
About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.