Clean Air Markets
CAIR Frequent Questions – Program Costs and Caps
Q: How does CAIR address growth of existing EGUs and new facilities that will start up in the future?
A: The IPM modeling used to project the emission reductions under CAIR accommodates future growth in demand. The results indicated that, even with the projected future growth, the power sector has highly cost-effective emission reductions. New units would be included under the CAIR emissions caps to ensure that emissions do not grow because of new sources and that all of the expected benefits of the rule are achieved.
Q: Will EPA make the TRUM model that it used to perform its marginal cost analyses available to the States and the public along with an explanation of the model ? (pg. 25204)?
A: The model is explained in the technical support document entitled: “Analysis of the Marginal Cost of SO2 and NOx reductions,” January 28, 2004. EPA is working to make the model available to States.
Q: Why did EPA model 2010 SO2 emissions at 5.3 million tons, Figure IV-3, TRUM Analysis, pg. 25213)? The 2010 CAIR SO2 cap is 3.6 million tons. Did EPA also model marginal costs with TRUM for 2010 with SO2 emissions at 3.6 million tons?
A: As explained in the technical support document entitled, “Analysis of the Marginal Cost of SO2 and NOx reductions, “January 28, 2004, SO2 control level can affect dispatch and fuel use, which can in turn affect marginal cost for control of NOx. We picked an SO2 level within the range of policy options being considered, to properly account for the impact it would have on dispatch and fuel use and therefore correctly project marginal cost.
Q: Why did EPA model 2015 SO2 emissions at 4.1 million tons, Figure IV-3, TRUM Analysis, (Fed. Reg. page 25213)? The 2010 CAIR SO2 cap is 2.5 million tons. Did EPA also model marginal costs with TRUM for 2010 with SO2 emissions at 2.5 million tons?
A: As explained in the technical support document entitled, “Analysis of the Marginal Cost of SO2 and NOx reductions,“ January 28, 2004, SO2 control level can affect dispatch and fuel use, which can in turn affect marginal cost for control of NOx. We picked an SO2 level within the range of policy options being considered, to properly account for the impact it would have on dispatch and fuel use and therefore correctly project marginal cost.
Q: EPA's analyses show, that with widespread use of SCR, U.S. coal-fired EGUs are achieving NOx emission rates of 0.06 lb/mmBtu and below, and that even lower average NOx emission rates are more highly cost-effective than rates considered in the past (based on analyzing EGUs), possibly on the order of 0.12 lb/mmBtu or less" (Fed. Reg. page 25205). With this is mind:
- Why isn't CAIR based on a NOx rate of 0.12 lb/mmBtu or less?
A: As explained on 70 FR 25206, the projected NOx emission rate under CAIR in 2015 is 0.11 lbs/mmbtu.
- Why is EPA still proposing a NOx rate of 0.20 lb/mmBtu for BART? (pg. 25209).
A: Since receiving this question, EPA has finalized the BART rule. The preamble for the final BART rule discusses presumptive BART NOx limits for EGUs and can be found at https://www.epa.gov/visibility/actions.html#bart1.
Q: Since marginal cost curves show that greater emission reductions can be achieved "cost effectively," why aren't the caps (or emission reduction targets) at these higher cost-effective levels?
A: As explained on 70 FR 25225, EPA used a number of factors in addition to the highly cost effective criteria in setting the emission reduction requirements.