As U.S. policymakers consider how to tackle the challenge of greenhouse-gas constraints, the U.K.’s approach to the problem offers instructive examples.
A Multi-Pollutant Strategy
An integrated approach could prove more effective for controlling emissions.
February 2002. Several other members of Congress proposed competing legislation with a few fundamental differences, but also a good deal of common ground, including reliance on emission caps and trading. The impetus was provided by now-familiar facts, with a growing sense of urgency. Forty percent of the U.S. population was living in counties with air quality concentrations above the NAAQS, and the power sector was contributing a significant amount to the problem. There were many possible ways to implement the Clean Air Act and the power industry already was dealing with restructuring challenges.
The president’s Clear Skies proposal used cap-and-trade programs to phase in mandatory reductions of SO 2, NOx, and mercury. At full implementation, these caps would achieve a 73 percent reduction of SO 2 from 2000 levels (equivalent to a 68 percent reduction from Title IV levels), 67 percent reduction of NOx from 2000 levels, and a 69 percent reduction of mercury from 1999 levels. (The administration also proposed a separate, voluntary program to improve the carbon efficiency of the economy.) EPA projected Clear Skies would deliver $138 billion in annual health and environmental benefits by 2020 at a cost of $8 billion. 10
Clear Skies was billed as a simpler and more certain path allowing for strategic planning and co-benefits from control technologies ( i.e., mercury removal). But even with increasing, broad-based support for an integrated strategy, the legislation failed. It did generate a great deal of debate, but its progress was hindered primarily by disagreements over the failure to include CO 2 (as several competing bills did), the timing and level of the mercury cap, as well as reliance on mercury trading, and provisions that streamlined the existing Clean Air Act.
In October 2005, EPA released its analysis of the costs and benefits of Clear Skies and alternative approaches, including EPA’s CAIR/CAMR/CAVR, Senator Carper’s (D-Del.) Clean Air Planning Act (CAPA), and Senator Jeffords’ (I-Vt.) Clean Power Act (CPA). It demonstrates how the SO 2 reductions from these (and previous) approaches stack up relative to each other and to 2007 emissions (see Figure 2) . The differences are not as significant as one would expect. Comparing reductions for NOx is less straightforward given seasonal and geographic variations, but the overall relative picture is similar to SO 2. The differences are more apparent in the case of mercury (particularly the extent of trading) and CO 2 (whether or not it is regulated).
Senator Carper’s CAPA of 2003 would have set a nationwide, three-stage, declining cap for SO 2 emissions, with caps implemented in 2009, 2013, and 2016, resulting in a 76 percent decrease in SO 2 emissions from Title IV levels at full implementation. Additionally, CAPA would have reduced NOx and Hg emissions by implementing nationwide caps in 2009 and 2013. The NOx caps ultimately would achieve the same emission reductions as the Clear Skies NOx program, but in a shorter timeframe, while the final mercury cap would reduce mercury emissions 33 percent beyond Clear Skies (the mercury caps were supplemented with unit-specific limits). CAPA also would