SO2, NOx cuts needed to protect ecosystems, report says
Washington, 20 January (Argus) — Further emissions cuts from the utility sector are needed to allow for ecological recovery in acid-sensitive areas despite the success of the Clean Air Act Title IV SO2 trading program according to a government report recently submitted to Congress.
Power sector SO2 and NOx emissions must be reduced to below 1.1mn and 0.44mn short tons/yr, respectively, by 2020 to reduce the number of lakes with acute acid deposition issues, according to the 2011 National Acid Precipitation Assessment Program Report to Congress. To fully protect the lakes in the northeast, SO2 emissions would have to be 0.44mn st/yr or less. Ecological recovery in the southeast will take longer because the soil there retains sulfur. Even with the extreme emissions reductions, 13pc of streams in the southeast would have elevated sulfur concentrations in 2050.
Title IX of the Clean Air Act requires an assessment to be submitted to Congress every four years that details the costs, benefits and effects of the Title IV Acid Rain Program and further measures necessary to protect ecological health. It is conducted by a cooperative federal program that includes representatives from the Environmental Protection Agency, the Departments of Energy, Interior and Agriculture, the National Aeronautics and Space Administration and the National Atmospheric and Oceanic Administration.
Utilities covered by the Acid Rain Program have reached 100pc compliance with the SO2 caps since 2005 either through on-site reductions or by trading allowances. A bank of 15.3mn allowances that can be used for future compliance has grown as emissions fall further below the statutory limit. The bank is expected to grow further after 2011 compliance.
“The program has met its environmental goals” and “new and emerging programs will likely lower power sector SO2 and NOx emissions in the future,” the report said.
The program has had significant results. Between 1990 and 2009, 41 states and DC cut SO2 by a total of 10mn st while seven states — Idaho, Montana, Nebraska, North Dakota, Oregon, Rhode Island and Vermont — saw emissions increase by a combined 39,521st. NOx emissions from sources covered by the Acid Rain Program dropped by 4.1mn st, or 67pc, in the same timeframe.
The report also tracked decreased ambient SO2 concentration and sulfur deposition levels and found a principal reason for decreased sulfate deposition levels in the northeast is a reduction in the long-range transport of sulfate from emission sources located in the Ohio River valley. The Clean Air Interstate Rule (CAIR), which was adopted in 2005 and the Cross-State Air Pollution Rule finalized last year were intended to address the interstate transport of SO2, NOx and particulate matter.
The cross-state rule, which is on hold pending a court's decision on its legality, would cut SO2 emissions from 23 eastern states to 3.24mn st/yr in 2012, down only slightly from the 3.25mn st cap set by CAIR. NOx emissions would drop more significantly, with annual levels falling to 1.16mn st/yr under the cross-state rule, relative to 1.33mn st under CAIR and ozone NOx emissions dropping from 0.56mn to 0.49mn st.
Power sector SO2 emissions would have to be cut by an additional 90pc to reach 0.44mn st/yr, relative to the emissions levels expected to be achieved under CAIR and other existing air quality standards. To cut NOx emissions to 0.44mn st/yr power sector emissions would have to fall by about 80pc. Sources outside of the power sector such as industrial boilers would have to reduce emissions an additional 50pc, according to the report.
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