South Carolina Electric & Gas (SCE&G) has retrofitted some coal capacity to meet new air regulations while it also has smaller and older coal units that are in the process of being retired.
The utility described its latest plans in that regard in an annual Integrated Resource Plan (IRP) filed on Feb. 28 at the South Carolina Public Service Commission. The IRP covers the next fifteen years, 2014 through 2028.
In order to reduce NOX emissions and to meet compliance requirements, SCE&G installed Selective Catalytic Reduction (SCR) equipment at its 415-MW Cope Station in the fall of 2008. It is capable of reducing NOX emissions at Cope Station by about 90%. SCE&G is also utilizing the existing SCRs at Williams (605 MW) and Wateree (684 MW) stations along with previously installed low NOX burners at the other coal-fired units to meet the Clean Air Interstate Rule (CAIR) requirements for NOX which are in effect while the Cross State Air Pollution Rule is under a court-ordered stay.
SCE&G has installed flue gas desulfurization (FGD) equipment, commonly known as wet scrubbers, at the Williams and Wateree stations to reduce SO2 emissions. The in-service dates for Williams and Wateree were February 2010 and October 2010, respectively. Scrubber performance tests at both stations met the SO2 designed removal rate of 98%. Mercury emission control has also been realized via the operation of FGD equipment. Consequently, the continued operation of the FGD equipment will contribute to SCE&G’s strategy for meeting the impending requirements of the U.S. Environmental Protection Agency’s Mercury and Air Toxics Standards (MATS) that will become effective on April 16, 2015.
The Chem-Mod fuel additive being used on the coal at McMeekin, Cope and Williams will similarly contribute to SCE&G’s efforts in stack emission control for mercury, as well as for NOX and SO2.
In response to MATS, the last coal-fired boiler at Urquhart Station, Unit 3, was converted to natural gas. Decommissioning of the plant’s former coal handling facilities is in progress. Also in response to MATS, Canadys Station ceased operations on Nov. 6, 2013, and decommissioning efforts are in progress.
Utiility got MATS extensions for two plants, but will only need one of them
The MATS rule takes initial effect in April 2015, but states can grant one-year extensions. A one-year extension may be granted by the state permitting authorities if additional time is needed for units that are required to run for reliability purposes which would otherwise be deactivated, or which, due to factors beyond the control of the owner/operator, have a delay in installation of controls or need to operate because another unit has had such a delay. A second year of extension may also be possible for reliability critical units that qualify for an Administrative Order at the end of the one-year extension.
SCE&G applied for and received a one-year extension from South Carolina regulators for both McMeekin and Canadys. With the retirement of Canadys in the fourth quarter of 2013, only McMeekin has a waiver that will allow the continued use of coal until April 2016.
When the EPA promulgated MATS in 2011, SCE&G had six small coal-fired units in its fleet totaling 730 MW ranging in age from 45 to 57 years that could not meet the emission standards without further modifications to the units. Those six units are:
- Canadys 1, 90 MW, commercial in 1962;
- Canadys 2, 115 MW, 1964;
- Canadys 3, 180 MW, 1967;
- Urquhart 3, 95 MW, 1955;
- McMeekin 1, 125 MW, 1958; and
- McMeekin 2, 125 MW, 1958.
After a thorough retirement analysis, the company decided that these six units would be retired when the addition of new nuclear capacity was available as a replacement. As part of this retirement plan, SCE&G has retired Canadys Units 1, 2 and 3 and has converted Urquhart 3 to be fired with natural gas while dismantling the coal handling facilities at this unit. The capacity (250 MW) of the remaining two coal-fired units, McMeekin 1 and 2, is required to maintain system reliability until the new nuclear capacity is available. The company is currently looking at ways to bridge, with dispatchable resources, the gap between the extended MATS compliance date of April 2016 and the availability of the new nuclear capacity.
SCE&G owns and operates six coal-fired fossil fuel units, one gas-fired steam unit, eight combined cycle gas turbine/steam generator units (gas/oil fired), sixteen peaking turbine units, fourhydroelectric generating plants, and one Pumped Storage Facility. In addition, SCE&G receives the output of 85 MW from a cogeneration facility. The total net non-nuclear summer generating capability rating of these facilities is 4,590 MW in summer and 4,764 MW in winter. When SCE&G‟s nuclear capacity (647 MW in summer and 661 MW in winter), a long term capacity purchase (25 MW) and additional capacity (20 MW) provided through a contract with the Southeastern Power Administration are added, SCE&G’s total supply capacity is 5,282 MW in summer and 5,470 MW in winter.