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Air Quality

Clean Air Interstate Rule (CAIR) - Allocations

CAIR is in effect while EPA develops a replacement rule to respond to the U.S. Court of Appeals, D.C. Circuit, remand on December 23, 2008.

Compliance Supplement Pool (CSP)

Please use the links below for more information on the Compliance Supplement Pool of the CAIR program.


DHEC, in cooperation with the Clean Air Markets Division of the EPA, administers the CAIR NOX Trading Program. DHEC determines the Compliance Supplement Pool allocations, also known as allowances or NOX credits, for each facility subject to CAIR in South Carolina.

DHEC will distribute Compliance Supplement Pool allocations in the 2009 control period only, and will be vintage year 2009. DHEC submitted the following Compliance Supplement Pool allocations to EPA on November 17, 2009: SC CSP Allocations 2009 (xls)

Compliance Supplement Pool allocations are for NOX Annual Sources only, not NOX Ozone Season Sources.

EPA will retire unused CSP allowances.

South Carolina's Compliance Supplement Pool is 2,600 tons of CAIR NOX allowances.

Timing Requirements for the Compliance Supplement Pool

By May 1, 2009, allowance request submittals are due to DHEC.

By November 30, 2009, DHEC will determine Compliance Supplement Pool allowances awarded to each unit and submit them to EPA.

By January 1, 2010, the EPA will record the CSP allocations.


1. Any South Carolina facility that is subject to the CAIR NOX trading program that achieves NOX emission reductions in 2007 and 2008 not necessary to comply with any applicable State or Federal emissions limitation.

2. Any South Carolina facility that is subject to the CAIR NOX trading program whose compliance with the CAIR NOX emissions limitation for the control period of 2009 would create an undue risk in the reliability of electricity supply during such period. The CAIR designated representative shall submit to DHEC a request for allocation of NOX allowances from the CSP, not exceeding the minimum amount of CAIR NOX allowances needed to remove such undue risk to reliability of electricity supply. Submittal must include a demonstration that shows it would not be feasible for the owners and operators of the unit to:

  • Obtain a sufficient amount of electricity from other electricity generation facilities, during the installation of control technology at the unit for compliance with the CAIR NOX emissions limitation, to prevent such undue risk; or
  • Obtain CSP allowances, or otherwise obtain, a sufficient amount of CAIR NOX allowances to prevent such undue risk.

Compliance Supplement Pool Process

DHEC will review each request. If the total amount of valid requests is less than the CSP, then each unit will be rewarded the total amount of valid allowances requested.

If the total amount of requests is greater than the CSP, then each unit will be rewarded allowances pro rata.

  • See South Carolina Air Pollution Control Regulation 61-62.96.143(d)(3)
  • Units Allocation = Unit's Adjusted Allocation * (State CSP / Total Adjusted Allocation for all units)
  • e.g. 100 tons * (2600 / 4,000) = 65 tons

To determine valid allowance requests, DHEC used the following formula:

CSP Tons per month
[ 0.25(lb/mmBtu)-Actual Rate(lb/mmBtu) ] * Heat Input
2,000 lb/ton

The applicable ceiling, or the amount from which the actual NOX emissions rate is subtracted, may not be set equal to the NOX SIP Call ceiling, 0.25(lb/mmBtu) if facility is subject to a more stringent federal or state limit, such as a Permit limit.

The facility must voluntarily elect to implement NOX control measures in the 7 months outside the Ozone Season.

For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.