Although the industries are diverse, their emission processes are often similar. For example, many industries use common unit operations, such as industrial furnaces to generate steam for process use, whereas others use combustion sources, such as tunnel or rotary kilns.
There is substantial variation among states regarding the implementation status of the NSR revisions and the existence of a minor-construction permitting program that might cover modifications that are not covered under NSR. There is limited experience with NSR revisions where the programs have been implemented. Furthermore, there appears to be reluctance by some states and firms to conduct permitting, given the current uncertainty about litigation over the revisions.
There is a lack of systematic and consistent reporting of NSR permits by states. However, some states appear to be adopting a common framework for electronic management of permits.
A review of common repair and replacement practices for selected types of process facilities showed that such activities can vary considerably in frequency and cost.7 Likewise, for a given emission source, such as a boiler at an electricity-generating plant, the wide array of pollution-prevention and -control options can vary in effectiveness and cost.
Emission sources, pollution-prevention techniques, and pollution-control technology are expected to change, and regulations like those considered here can be part of the motivating factors for such change. However, the effects of regulations can vary greatly, depending on the specifics of programs.