ENVIRONMENTAL REGULATIONS AND PERMITTING
Air pollution emissions from a fossil fueled
Air Quality Regulations.
steam power plant are regulated by the Federal Government under the Clean Air Act (42
USC & 7401 et seq.). Each of the states also regulates air pollution emissions. All
facilities must comply with both Federal regulations and state (and local) regulations.
The facility will have to be designed to meet the most stringent requirements.
Stack emissions are limited by direct emission limits. This is the
pollutant concentration in the flue gas emissions measured in the stack. Stack
emissions may also be limited by ambient air quality limitations. These are standards
based on measured or calculated pollutant concentrations at ground level off the site
of the pollutant source.
The stack emissions of major concern in a fossil fueled steam power plant
are sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter. Of lesser
concern are carbon monoxide (CO) and various trace elements such as mercury and
beryllium. The formation of the major pollutants and their control is discussed in
Section 17 of this handbook.
National Ambient Air Quality Standards. The National Ambient Air Quality
The entire United States. is supposed to have air quality at least as good as the NAAQS.
Any place where the air quality is worse than the NAAQS is said to be a "nonattainment"
area. An area can be a nonattainment area for one pollutant and an attainment area for
another. Each pollutant is characterized separately. The NAAQS is important to stack
emissions because a new facility will not be permitted if calculations (modeling) show
that the NAAQS would be exceeded at any point off the facility site. To find out if the
NAAQS would be exceeded, the existing pollution level (background) must be known. The
modeled impacts of the proposed facility are added to the background. It may be
necessary to limit the emissions from a new source so that the NAAQS are protected.
The NAAQS values for all six "criteria" pollutants are given in Table 30.
These six pollutants include the three major pollutants discussed above; SO2, NOx, and
particulate matter. The primary standard is established at the level requisite to
protect the public health and allowing an adequate margin of safety. The secondary
standard is established at the level requisite to protect the public welfare (such as
vegetation) from any known or anticipated adverse effects associated with the presence
of such pollutants in the ambient air.