The Florida Department of Environmental Protection went out for comment on March 12 on a tentative approval of a one-year extension of the April 16 deadline for compliance under the federal Mercury and Air Toxics Standards (MATS) for Duke Energy Florida‘s coal-fired Crystal River Units 4 and 5.
Duke Energy Florida applied on Jan. 13 at the DEP for this extension to April 2016. The Crystal River facility consists of the South Plant, which includes two coal-fired facilities (Units 1 and 2) that began operation in the 1960s, and the North Plant, which includes two coal-fired generators (Units 4 and 5) that began operation in the 1980s. All four units are subject to EPA’s MATS rule. Units 1 and 2, which the utility plans to retire by 2018, are not involved with this extension. Unit 3 is a retired nuclear facility.
“Based on recent monitoring and testing as described previously in a letter to DEP and summarized in this report, DEF is submitting a Title V air operation permit revision application to install and operate additional mercury emission control systems for Units 4 and 5,” said the Jan. 13 application. “Due to the lead time needed for the design, installation and operational tuning, DEF is requesting a one year extension of the MATS compliance requirements for Units 4 and 5.”
The application added: “Despite several years of monitoring for confirmation of existing controls, a change in mercury emissions was only recently observed, and was beyond reasonable control. DEF first learned of an individual occurrence of a spike in mercury emissions from Unit 5 in July 2014. The mercury emissions returned to within the normal range of the previous two years, but September resulted in a second peak. DEF commissioned a study to identify the cause and options for control. As described further in subsequent sections, an extension of the MATS compliance date for Units 4 and 5 is necessary to provide sufficient time to fully implement controls to mitigate re-emission of mercury.”
The utility wrote: “To further investigate and mitigate mercury re-emissions, DEF is expediting the installation of a re-emissions chemical additive system. This system in being used successfully on several other units within the Duke Energy fleet. Operating conditions and FGD chemistry vary from unit to unit; therefore, testing on Units 4 and 5 is necessary to determine whether this chemical will be effective. Initially, DEF will install a temporary system to conduct this testing and investigate appropriate chemical injection rates. DEF expects to install the system in the February/March 2015 timeframe. In parallel, DEF must design and install a permanent system, followed by testing and tuning of control logic. The permanent system must utilize a mercury [continuous emissions monitor] as an input to the control logic. The signal from this CEM will be used for determining the chemical injection rates. By contrast, the temporary system will rely on feedback from the existing sorbent traps, which provide mercury emissions results with a 10-14 day lag time. The mercury CEM and its associated equipment have the longest lead times for implementation.”
The DEP said in a March 12 notice that the U.S. Environmental Protection Agency has agreed to perform its 45-day review provided by the law and regulations concurrently with the state’s 30-day public comment period, provided that the applicant also transmits an electronic copy of the required proof of publication directly to EPA. The final Title V air operation permit will be issued after the conclusion of the 45-day EPA review period so long as no adverse comments are received that result in a different decision or significant change of terms or conditions.
Units 4 and 5 each consist of a pulverized coal, dry bottom, wall-fired boiler rated at 760 MW. They share a common 550 foot tall chimney with separate internal stack liners with continuous emissions monitoring systems on each stack liner. Air pollution control equipment on Units 4 and 5 includes: low-NOX burners; selective catalytic reduction systems; AMM systems; an electrostatic precipitator; and relatively new flue gas desulfurization systems.