Clean Air Act Nitrogen Oxides (NOx) Scenario Descriptions

Background:

These scenarios have been run by Robin Dennis in the year 2001 using the extended version of the
Regional Acid Deposition Model (Extended-RADM) located at Research Triangle Park, NC. RADM
has ended and a new model (CMAQ/Models-3) will be available for use in 2003. All scenarios
described are for changes in nitrate-nitrogen deposition only. At this time, there are no regulated
emissions controls for ammonia.

Scenario 1 "2007/2010 Base with NOx SIP"

This model run is the Basic 1990 Clean Air Act projected for the year 2010. This scenario includes
regulations that have passed.

2007 non-utility and area source emissions.

2007 mobile source with Tier II tail-pipe standards on light duty vehicles.

2010 utility emissions: Title IV (Acid Rain Program) fully implemented; the 20-state NOx SIP call
reductions @ 0.15#/MMbtu. This would be during the ozone season only (May to
September).

Scenario 2 "2020 CAA: With Tier II & Heavy Duty Diesel Regulations"

This model run includes Scenario 1, PLUS new heavy duty diesel regulations.

2020 non-utility and area source emissions (no additional controls).

2020 mobile source with Tier II tail pipe standards on light duty vehicles (which are now more
effective), and heavy duty diesel standards to further reduce NOx emissions.

2020 utility emissions described in Scenario 1.

Scenario 3 "2020 CAA with Aggressive Utility Controls"

This model run includes Scenario 2, PLUS stringent new utility reductions in S02 and NOx.
2020 non-utility and area source emissions. (Same as Scenario 2)

2020 mobile source with Tier II tail pipe standards on light duty vehicles (now more effective), and

heavy duty diesel standards to further reduce NOx. (Same as Scenario 2).

2020 utility emissions with major reductions in S02 (90% reduction) and further NOx reductions

through 2 paths: utilities go to 0.10#/MMbtu for the entire year. No longer just seasonal

reductions.

Scenario 4 "2020 CAA with Aggressive Utility Controls and Industry-Point and Mobile Controls"

This would be Chesapeake Bay's "Limit of Technology" Scenario.

This model run includes Scenario 3, PLUS reductions in non-utility source emissions and mobile source
emissions.

2020 non-utility (industrial) point emissions cut almost in half for both S02 and NOx.

2020 area source emissions (same as in Scenarios 2 &3).

2020 mobile source: heavy duty diesel standards to further reduce NOx, PLUS super ultra-low

emission vehicle assumed for light duty vehicles.

2020 utility emissions with annual reductions as described in Scenario 3.

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