Clean Air Act - Inhibits Acid Rain

The original Clean Air Act was established by the Environmental Protection Agency (EPA) in the 1970s. At the time, there were few, if any, provisions made for the reduction od acid rain causing gases. Basically, the Clean AIr act  was the first major legislation aimed at cleaning up our air. Later, there were amendments made to the act. It is in these amendments that we obtained regulations for the production of both SO2 and NOx.

EPA released amendments to the Clean Air Act. In these amendments, EPA made provisions for acid rain, commonly known as Titile IV. Although the provisions affect only a small amount of the sources of acid rain gases, the improvements caused are expected to be significant. With the creation of Title IV, EPA implemented two new concepts. These concepts are:

1. Emissions Trading

2. National Emissions Cap

In order to accomplish its goals, Title IV established a nationwide system of SO2 emission allowances. These allowances are expressed in terms of tons of SO2 emitted per year, and the basic allowance is emission of 1 ton per year of SO2. It is important to note that no source affected by Title IV can emit SO2 without holding an allowance for the emission. If a source does this, it may have to face judicial action. Also, if a source want to increase production and therefore increase emissions, it must obtain an emission allowance from another source that has reduced emissions. This is known as emissions trading.

In addition to the SO2 reduction, Title IV calls for a 2 million ton reduction in NOx. This reduction will be accomplished through burner modifications and will be measured from the amount of NOx that would have been emitted, if no modifications had been made. In terms of NOx emissions, Title IV does not require that industries install post combustion controls for monitoring. Also, unlike the SO2 emission reduction program, there is no NOx emission allowance system or emission cap for NOx.

Current Initiatives On Prevention Of Acid Rain

The major player with respect to acid rain prevention, not surprisingly, is the federal government. Because fossil fuel combustion is the aggravating circumstance in nearly all acid rain, efforts to reduce smokestack and tailpipe emissions on a national basis have been and remain a high priority for the Environmental Protection Agency. EPA’s most visible current goal is passage of so-called “clear skies” legislation, designed to produce a substantial reduction in sulfur dioxide and nitrous oxides. EPA submitted a set of proposals to the U. S. Congress , and re-introduced similar measures in February of this year, with final action still pending. EPA says its proposals would cut power plant emissions of SO2 and NOx by 70 percent by the year 2020, eliminating 35 million more  tons of these pollutants than the current Clean Air Act would allow during the same time frame.

Organizations are leading preservation efforts:
One of the leading players in materials preservation is the National Park Service, which supports the National Center for Preservation Technology and Training (NCPTT) in Natchitoches LA. The National Trust for Historic Preservation in Washington DC is a private organization which also devotes considerable resources to preservation research. NCPTT, created by an act of Congress, is an interdisciplinary program whose stated mission is “to advance the art, craft and science of historic preservation in the fields of archeology, historic architecture, historic landscapes, objects and materials conservation, and interpretation.” Because such a large number of culturally significant sites are privately held, NCPTT actively shares its research, education and information management resources with private practitioners. Having started up operations less than a decade ago , the Center provides evidence of the government’s growing concern about the long-term effects of acid rain and other pollutants on vulnerable structures.

Monitoring Of Acid Rain

Continuous emissions monitors (CEMs) tell us how much of a pollutant a power plant (or other affected facility) emits. Under the Acid Rain Program, each affected unit must monitor emissions of sulfur dioxide and nitrogen oxides. Most also measure carbon dioxide. CEMs are the most common way to monitor emissions, but in some cases, Utilities may use an approved alternate method. For example, if a unit burns oil and they know the sulphur content of the oil and the amount they used, they can compute the amount of sulphurdioxide they will emit.

Each plant in the acid rain program must submit a monitoring plan to EPA and revise it as their monitoring system changes. This document tells which monitors will be used, where they will be located, and how the data will be gathered and sent to EPA. If a plant’s monitoring system changes, they must revise their monitoring plan.

There are several ways to monitor emissions from a plant. We measure nitrogen oxides by taking a sample of the gas emitted thought the plant’s smokestack and analyzing it. In some cases sulphurdioxide is measured this way, but we can also compute sulphur emissions from the fuel’s sulphur content, as noted above. When plants use natural gas, which contains only traces of sulfur, we may estimate the plant’s emissions by assuming the gas contains a certain low amount of sulfur. Sulfur emissions from such plants are so low that an actual measurement of sulfur dioxide is impractical.

Power plants must submit data whenever they are operating. If their monitor is not operating, they must report a "default" value, which is generally the maximum amount of the pollutant they can emit. EPA gathers the data, and tabulates the emissions form each plant.