Republican senators James Inhofe and George Voinovich have reintroduced the Clear Skies Act of 2005, the latest version of President Bush’s Clear Skies proposal which would see power plant emissions in SOx, NOx and mercury cut by 70% by 2018.

Inhofe, chairman of the Committee on Environment and Public Works, and Voinovich, chairman of the subcommittee on Clean Air, Climate Change, and Nuclear Safety, unveiled the bill that centres on expanding the existing cap-and-trade Acid Rain Trading Program and by creating a new programme for mercury emissions.

The bill expands the Acid Rain Program to nationally reduce power plant emissions of sulphur by establishing new caps and allocation procedures starting in 2010. These include a Phase 1 cap for 2010 – 2018 of 4.5 million tonnes annually and a Phase 2 cap after 2018 of 3.0 million tonnes annually.

The bill retains the requirements of the existing Acid Rain Program for nitrogen oxides and the requirements of the State Implementation Plan through to 2007, but also establishes new caps and allocation procedures starting in 2008 with separate cap-and-trade systems for Zone 1 – covering eastern and central US – and Zone 2 for the western US and territories. Under the terms of the bill, the Zone 1 cap for phase 1 of 2008 – 2017 is set at 1.562 million tonnes annually, while the Zone 1 cap for phase 2 after 2018 is 1.162 million tonnes annually. The Zone 2 cap after 2008 is 0.538 million tonnes annually.

The bill also establishes the first ever caps and allocation procedures for mercury emissions, starting in 2010. Under Phase 1 from 2010 to 2017 the cap is set at 34 tonnes annually. After 2018 the Phase 2 cap is set at 15 tonnes annually.

In addition, the New Source Review (NSR) legislation is to be reformed to exempt affected units from the major source reconstruction review requirements of NSR and for 20 years the requirement to install Best Available Retrofit Technology, since emissions are capped at stringent levels. Similarly, the bill precludes affected generators from regulation of mercury using maximum available control technology standards, since mercury emissions are also being capped, but preserves the EPA’s authority to regulate hazardous air pollutants. Those plants located within 50 km of a national park also remain subject to specific Clean Air Act requirements.

According to the senators, Clear Skies, along with new diesel regulations already finalised by the EPA, will allow the country to attain National Ambient Air Quality Standards (NAAQS) by placing most of the burden on the generation sector. However, in contrast to other proposals, Clear Skies will not dramatically reduce coal-based generation or force an over-reliance on natural gas.