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| − | ===7. Environmental Aspects of Grid Interconnection===
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| − | ==7.1. Introduction==
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| − | Construction and operation of transmission grid interconnections, and the power plants that feed them,
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| − | have impacts—both positive and negative—on the local, and sometimes regional and global environments.
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| − | In addition, transmission grid interconnections will affect the generation of electricity in the
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| − | receiving country, and also, possibly, the production and use of other fuels. Evaluating and accounting
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| − | the full-fuel-cycle environmental impacts of grid interconnections is an important element of the overall
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| − | process of evaluating grid interconnection opportunities. Impacts and benefits may occur at any or all
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| − | points in the fuel chain, from extraction of fuels for electricity generation, to construction and operation
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| − | of plants and construction and operation of transmission facilities. Environmental considerations have
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| − | sometimes received less emphasis in energy planning in general than technical, economic, and (often)
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| − | political issues. In the case of grid interconnections in developing regions, however, the early consideration
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| − | of environmental impacts in evaluating interconnection options will help to identify key potential
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| − | problems—including sensitive ecosystems to be traversed by the power lines—as well as potential opportunities
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| − | that could enhance the interconnection project—including credits for avoided air pollutant and
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| − | greenhouse gas emissions115.
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| − |
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| − | ==7.2. Overview of Potential Environmental Benefits and Costs of Grid Interconnections==
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| − | Most of the potential classes of environmental benefits of grid interconnections are treated in more detail
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| − | in later sections of this Chapter. A brief listing of these benefits and impacts is presented here by way of
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| − | an introduction to the variety of environmental issues that should be considered.
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| − | • Air pollutant emissions including local air pollutants, regional air pollutants (such as the precursors
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| − | of acid precipitation and some particulate emissions), and greenhouse gases. Modest quantities of
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| − | emissions may be produced during power line construction, but the main influence of grid interconnections
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| − | on air pollutant emissions will be through the impact of transmission interconnections
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| − | on which power plants are run where and when in the interconnected nations. Major air pollutant
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| − | emission benefits therefore accrue overall (counting all the countries in the interconnection project)
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| − | if the emissions from the generation that is used with the interconnection in place is less than the
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| − | emissions that would have been produced in the absence of the interconnection. Where hydroelectric
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| − | generation, for example, provides export power through an interconnection and displaces existing or planned fossil-fueled power plants in the importing country, net emissions benefits will occur
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| − | in most cases. The net air pollutant emissions benefits or costs for individual countries depend on
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| − | which power plants run more, or less, in the presence of the interconnection, and where those plants
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| − | are located.
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| − | • Water pollution impacts, including erosion and water pollutants produced as a result of power line
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| − | construction and operation, and incremental water pollution from power plant construction, power
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| − | generation, and fuel extraction/storage. As with air pollutant emissions, on a net basis, overall water
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| − | pollution impacts can show either a net cost or a net benefit for the interconnection project as a
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| − | whole, or for the different countries and localities involved, depending on the specifics of how the
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| − | project is configured, and what would energy facilities would have been built and operated had the
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| − | interconnection not been built.
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| − | • Solid waste impacts, mainly coal ash and high- and low-level nuclear wastes from electricity generation,
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| − | but also including wastes from fuel extraction and possibly from power line and/or power plant
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| − | construction. Net solid waste benefits accrue to the project mostly if coal-fired power is displaced
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| − | by hydro, renewable, or gas-fired power, which net solid waste costs will occur, overall, if coal-fired
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| − | plants are built to fuel the production of power exported over the interconnection.
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| − | • Land-use impacts, including costs such as the restriction of uses of land through which a power line
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| − | passes, and benefits such as potential avoided land-use impacts from electricity generation or fuel
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| − | extraction facilities avoided by the use of an interconnection.
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| − | • Wildlife/biodiversity impacts, including costs such as the potential impacts of power line construction
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| − | and operation on flora and fauna in the power line area, and benefits such as potential avoided
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| − | impacts due to avoided generation and fuel extraction.
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| − | • Human health impacts, including the impacts of electromagnetic fields (EMFs) from power lines
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| − | on humans living and working in the power line vicinity (net costs of the interconnection project),
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| − | and benefits through avoided human health impacts through avoided air and water pollution.
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| − | As is clear from even these brief discussions of classes of impacts, international electricity grid interconnections
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| − | offer the potential for impacts at each different part of the fuel cycle. The full range of fuel
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| − | cycle steps at which environmental benefits and costs of an interconnection project can occur—through
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| − | impacts caused by the interconnection net of impacts avoided by the project relative to other means of
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| − | providing the same energy services as the interconnection—include construction of the power line and
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| − | related infrastructure, operation of the power line, construction and operation for the power plants feeding
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| − | the grid interconnection (or plants that are avoided by the use of the line), impacts related to fuel
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| − | supplies for power plants, and impacts related to power plant wastes.
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| − |
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| − | ==7.3. Potential Air Pollution Impacts of Grid Interconnections==
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| − | Grid interconnections may, depending on how they are configured, create or avoid (or both) air pollution
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| − | impacts as a result of their operation. The following subsections provide a review of the potential local,
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| − | regional, and global air pollution impacts and benefits from grid interconnections, summarize how the net
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| − | air pollutant emissions or emissions savings (and their impacts) of an interconnection might be assessed,
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| − | and briefly presents potential strategies for maximizing air pollution benefits of a grid interconnection.
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| − | Detailed evaluation of air pollution impacts at each of these scales can be extremely complex, and
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| − | many reports and, indeed, entire volumes, projects, and analytical tools have been dedicated to the evaluation
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| − | of air pollutant emissions and impacts116. The brief treatment below is therefore intended only as an
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| − | overview, to be considered as a generic structure underpinned by much more detailed work in the field
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| − | by a number of authors117.
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| − | Consideration of the net impacts of grid interconnections on air pollution involves consideration
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| − | of net emissions of in several pollutant classes and over the range of emissions sources that comprise the
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| − | full electricity generation/transmission/distribution fuel cycle. The type, timing, and location of pollutant
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| − | emissions need to be considered, as all of these elements play a role in determining the impacts of
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| − | emissions. Even a transmission interconnection that yields the same emissions, relative to a no-interconnection
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| − | alternative, can offer significant benefits if the power plants that run more to feed power to the
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| − | interconnection are far from population centers and/or sensitive environmental areas, and the power
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| − | plants that are operated less because the interconnection is used are located near population centers.
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| − | For analytical purposes, one way to divide the different types of air pollutant emissions is by the scale
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| − | of their impacts. A typical division of air pollutants by their scale of impacts is as follows:
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| − | • Local air pollutants, which typically largely affect the area in or near which they are emitted. Local
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| − | air pollutants can have impacts on human, animal, and plant health, as well as on visibility, and can
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| − | also have impacts.
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| − | • Regional air pollutants, including those pollutants that are play a role in acid precipitation, can
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| − | have a variety of impacts on health, ecosystems, and structures.
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| − | • Global air pollutants, particularly greenhouse gases, can affect global climate.
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| − | Individual air pollutant species may have impacts and one or more of these scales. The subsections
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| − | below provide brief discussions of air pollutants related to grid interconnections and their impacts at each
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| − | of these scales.
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| − | In general, this section attempts to include discussions of the air pollution impacts of all of the parts
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| − | of the full electric fuel cycle that might occur in any (or all) of the interconnected countries. In practice,
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| − | however, the major air pollutant emissions changes due to the installation of grid interconnections are likely
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| − | to be from power generation. Emissions from other parts of the fuel cycle, including air pollutant impacts
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| − | of line construction (including diesel exhaust and fugitive dust), are therefore mentioned, but not treated in
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| − | any detail, as these impacts are relatively transient and of short duration. The focus below is therefore on air
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| − | pollutant impacts of power system operation with and without a grid interconnection between nations.
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| − | ==7.3.1. Local air pollutant impacts==
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| − | The local air pollution impacts of power plants run to provide electricity for a line, and the local air pollution
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| − | benefits of not operating certain power plants due to the availability of electricity from a grid interconnection,
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| − | will be a function of the type of power plant used or avoided, its proximity to populations or
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| − | ecosystems that might be affected, the types of control equipment used on the plant, and the species of
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| − | pollutant emitted. Another key variable is atmospheric conditions, including the presence of other pollutants.
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| − | Many species of air pollutants react with each other and with other molecules in the atmosphere to
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| − | form compounds of greater concern. Photochemical smog is an example of a pollution problem caused by
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| − | the presence of several different pollutant species. The summaries that follow provide very brief reviews of
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| − | some of the key human health impacts of each pollutant species11 8.
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| − | • Carbon monoxide, or CO, which results from incomplete combustion of carbon-based fuels. Carbon
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| − | monoxide is typically a relatively minor component of emissions from electricity generation facilities
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| − | that are properly operated, as most electricity generation facilities burn fuels under conditions of excess
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| − | oxygen. Vehicle exhaust, on the other hand, including exhaust of transportation and heavy construction
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| − | equipment involved in power line construction, is often relatively rich in CO. Carbon Monoxide
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| − | is a local air pollutant with respiratory impacts, and contributes both directly (as it oxidizes to CO2)
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| − | and indirectly to the increase in greenhouse gas concentrations in the atmosphere (see below). CO’s
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| − | respiratory impacts on human and animal health stem primarily from the ability of the CO molecule
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| − | to bind to hemoglobin, the oxygen-carrying molecule in blood, and thereby reduce the supply
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| − | of oxygen to the brain in human and other tissues. Even relatively low concentrations of CO in
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| − | the air can lead to carbon monoxide poisoning, which is characterized by headaches, dizziness, and
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| − | nausea in mild cases, and loss of consciousness and death in acute cases.
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| − | • Sulfur oxides, of which sulfur dioxide (SO2), which is typically the major species in the broader class
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| − | of sulfur oxides (SOx, in general), are formed when the sulfur in fuel is oxidized during the combustion
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| − | process. As a consequence, SOx emissions, if not controlled, may be substantial for power plants
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| − | fired with relatively sulfur-rich fuels such as coal and heavy fuel oil. Some grades of diesel fuel also
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| − | include significant concentrations of sulfur compounds, and as a consequence the emissions from
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| − | trucks and other heavy equipment can be a source of SOx. SOx can react with water and oxygen in
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| − | the atmosphere to yield sulfuric acid, one of the major components of acid rain (see below). SO2
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| − | itself can damage plants, with acute exposure to the gas causing death of part or all of a plant, and
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| − | chronic exposure, though the threshold at which plants are affected varies widely among different
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| − | plant species. In humans, exposure to SO2 at high levels (above about 5 parts per million, or ppm;
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| − | the average concentration in urban air in the U.S. is about 0.2 ppm) causes respiratory problems,
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| − | though exposure to significantly lower doses can sometimes exacerbate existing respiratory problems
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| − | in sensitive individuals. In developing countries and other areas where coal is used as a home heating
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| − | and/or cooking fuel, SOx can be an important health hazard as an indoor air pollutant.
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| − | • Nitrogen oxides (NOx), principally NO and NO2, are formed both by oxidation of nitrogen compounds
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| − | present in fuel and by high-temperature oxidation of the molecular nitrogen that is the
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| − | main constituent of air. As a consequence, combustion of all fuels, even fuels with no nitrogen
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| − | component, can yield NOx. Nitrogen oxides can contribute to environmental problem in several
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| − | ways. Short-term exposure to elevated NO2 concentrations (0.2 to 0.5 ppm) can cause respiratory
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| − | symptoms among asthmatics. Indoor fuel combustion, particularly from gas stoves or traditional
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| − | fuel use, can lead to elevated indoor levels which have been associated with increased respiratory
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| − | illness and reduced disease resistance among children. Nitrogen oxides contribute to the formation
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| − | of tropospheric ozone and nitrate aerosols (fine particulates), which are major air pollutants in themselves.
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| − | Atmospheric emissions of NOx also contribute to the formation of the photochemical smog
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| − | prevalent in many urban areas, and thus have a general detrimental effect on the respiratory health
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| − | of humans and other animals, as well as on visibility. In high concentrations, NOx can injure plants,
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| − | though the required concentrations usually only exist near a large (and uncontrolled) point source of
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| − | the pollutant. The major hazard to plants from nitrogen oxide emissions may be through the effect
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| − | of NOx on ozone formation. Atmospheric nitrogen oxides in high concentrations cause respiratory
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| − | system damage in animals and humans, and even in relatively low concentrations they can cause
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| − | breathing difficulties and increase the likelihood of respiratory infections, especially in asthmatics
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| − | and other individuals with pre-existing respiratory problems.
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| − | • Volatile organic compounds, or VOCs, are sometimes referred to as “Hydrocarbons” or “Non-
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| − | Methane VOCs”. The many different species in this class of compounds results from incomplete
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| − | combustion of organic materials in carbon-based fuels, but combustion conditions play a critical
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| − | role in determining both the types and amount of VOCs emitted from a given device. Again, typically,
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| − | power plants that are well-run and in good condition will emit relatively low concentrations
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| − | of VOCs, as most VOCs in combustion gases will be fully oxidized to CO2, but poor or poorly
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| − | controlled power plant boilers, and many vehicle engines, can emit substantial concentrations of
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| − | VOCs. In addition to VOC emissions as products of incomplete combustion of carbon-based fuels,
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| − | VOCs are also emitted from evaporation or leakage of fuels and lubricants from fuel production,
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| − | transport, and storage facilities (for example, oil wells, tanker ships and trucks, and petroleum refineries)
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| − | or from fuel-using devices (such as automobile gas tanks and engine crankcases). Sub-classes of VOCs
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| − | that are often of particular include PAH (polycyclic aromatic hydrocarbons), POM (Polycyclic Organic
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| − | Molecules) and other VOC species whose molecular structure gives them biological activity of particular
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| − | importance. These and other individual VOC species exhibit various degrees of toxicity in different animal
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| − | species. Many hydrocarbons are also carcinogenic (promote the growth of cancers) and/or promote
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| − | genetic mutations that can lead to birth defects. As a class, hydrocarbons contribute to the production
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| − | of photochemical smog and of ground level ozone, which are dangerous to human health due to their
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| − | effects on the respiratory system. High ozone levels also damage crops, forests, and wildlife.
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| − | • Particulate matter, also referred to as “particulates”, “dust”, or “smoke”, and sometimes abbreviated
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| − | TSP for Total Suspended Particulates, includes a variety of different compounds—including inert
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| − | materials such as ash, organic molecules, unburned fuel, and particles of sulfate—that form microscopic
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| − | and larger particles. Particulate emissions are emitted by power plants (particularly those
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| − | burning coal and heavier oil fuels), and by heavy equipment using diesel fuel. Fugitive emissions of
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| − | particulate matter (such as wind-blown dust) related to energy facilities can come from coal storage
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| − | piles, coal mining operations, or ash storage of disposal sites. Particulate matter (PM) is often divided
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| − | into categories based on the average size of the particles. “PM10”, denoting the fraction of particulate
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| − | matter with particle diameter of 10 microns (10 x 10-6 meters) or less, and “PM2.5”, denoting the
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| − | fraction of particulate matter with particle diameter of 2.5 microns or less. The PM10 and PM2.5
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| − | fractions are important because they penetrate further into the respiratory system than larger PM
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| − | particles, where they can aggravate existing respiratory problems and increase the susceptibility to
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| − | colds and other diseases. Particulates can also serve as carriers for other substances, including carcinogens
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| − | and toxic metals, and in so doing can increase the length of time these substances remain in
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| − | the body. Particulate matter in the air impairs visibility and views, and particulate matter settling on
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| − | buildings, clothes, and other humans may increase cleaning costs or damage materials. Particulate
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| − | matter is an important indoor air pollutant in areas where open or poorly-vented household cooking
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| − | and heating equipment is used, particularly with “smoky” fuels such as wet biomass, crop and animal
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| − | residues, and low-grade coals. A subset of particulate emissions that has been a topic of considerable
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| − | research in recent years is “black carbon”, which, in addition to its local health and other impacts,
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| − | appears to have implications for regional climate, as described in section 2.3.3 below.
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| − | • Heavy metals are often associated with the combustion of coal and some heavy oils, and are often
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| − | emitted in association with particulate matter. Heavy metals of concern for emissions from energy
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| − | facilities include lead, arsenic, boron, cadmium, chromium, mercury, nickel, and zinc. The impacts
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| − | of metals on the environment and on human health vary with the metal element (and sometimes
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| − | compound) emitted, and how they are emitted—for example, as a part of particulate matter. Some
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| − | metals are plant nutrients in low concentrations, but toxic in higher concentrations. Metals of concern
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| − | in the environment include Lead, Arsenic, Boron, Cadmium, and Mercury, with human health
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| − | impacts ranging from central and peripheral nervous system effects to blood problems, carcinogenicity,
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| − | and birth defects. Heavy metals are often retained in the bodies of animals, and “bioconcentrated”
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| − | in the food chain, leading to high concentrations of heavy metals in animal species that are
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| − | “top predators” (such as large carnivorous birds, fish, and mammals).
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| − | • Radioactive emissions to the atmosphere stem primarily from the operation, maintenance, and
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| − | decommissioning of nuclear power plants and the production, refining, storage, and disposal of the
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| − | materials that fuel them, but can also be released in very small quantities during activities such as
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| − | coal mining and combustion. Routine emissions from nuclear reactor and nuclear fuel chain operations
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| − | are typically relatively minor. Accidents at nuclear facilities, however, can release radioactive
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| − | materials to the atmosphere ranging in amount from modest to highly significant. The effects of
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| − | radioactive emissions on human health have been documented119. These health effects include acute
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| − | effects such as radiation sickness (characterized by nausea, damage to bone marrow, and other symptoms),
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| − | and chronic effects such as increases in cancer rates, genetic effects, prenatal problems, effects on
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| − | fertility, shortening of life, and cataracts of the eye. It should be noted that the amount of radioactivity
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| − | to which the public is exposed during routine operation of nuclear plants is generally not thought to be
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| − | sufficient to contribute to these problems.
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| − | As possible configurations of grid interconnections often include trade-offs of fossil-fueled generation
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| − | in different locations, the net local air pollution benefits (or impacts) of a grid interconnection will in those
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| − | cases depend upon where the power plants run more and those that run less are located, as well as upon the
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| − | types of power plants (and their air pollution control equipment) in each case. For example, in Northeast
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| − | Asia, an interconnection that results in the extended use of coal-fired power plants in remote areas of the
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| − | Russian Far East but avoids coal-fired generation in more heavily populated China, the ROK (Republic
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| − | of Korea), or the DPRK (Democratic Peoples’ Republic of Korea) may result in a net positive impact on
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| − | human health, although such factors as topography, local weather conditions (and other local pollutant
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| − | emissions), and impacts on plants, (non-human) animals, and ecosystems must also be taken into account.
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| − | As noted by Dr. David Streets, the displacement of power generation from typically urban power plants in
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| − | China, Mongolia, and the DPRK, to remote areas of the RFE may result in considerably reduced human
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| − | exposure to air pollution hazards120.
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| − | Grid interconnections that result in improved availability of electricity in specific areas, particularly in
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| − | developing regions, may have significant impacts on local and indoor air pollution. To the extent that, for
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| − | example, electricity from a grid interconnection can offset the use of relatively poor quality or polluting
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| − | fuels, such as the use of low-quality coals or biomass for cooking and heating, the grid interconnection may
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| − | provide significant local health benefits.
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| − |
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| − | ==7.3.2. Potential regional air pollutant impacts==
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| − | Although some photochemical smog and other air pollution impacts can, at times, be sufficiently widespread
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| − | as to be nearly regional in nature, arguably the major regional air pollution impact is acid precipitation,
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| − | sometimes called “acid rain”, which is a significant environmental issue in North America,
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| − | Northern Europe, and Northeast Asia, though not yet a serious issue in other regions. Depending on
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| − | the way that a grid interconnection is operated, net regional emissions of acid gases could be reduced or
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| − | displaced. Brief descriptions of some of the issues associated with the emissions of air pollutant precursors
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| − | to acid precipitation are provided below122.
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| − | Acid deposition results when nitrogen and sulfur oxides (“NOx” and “SOx”) react in the atmosphere
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| − | with oxygen and water droplets to form nitric and sulfuric acids (HNO3 and H2SO4). As the water droplets
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| − | condense, they fall as rain, snow, or fog, hence the common name “Acid Rain”. While acid rain is the most
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| − | frequently discussed pathway for these compounds to return to earth, nitrates and sulfate ions123 (NO3
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| − | -and SO4 2-) also can combine with positive ions or adhere to the surface of particles in the atmosphere,
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| − | sometimes falling to earth in a dry form (“dry deposition”). SOx and NOx can also directly adhere to soil or
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| − | plant surfaces, eventually reacting with water and oxygen to form acids. As a consequence, the terms “Acid
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| − | Rain” and “Acid Precipitation” are somewhat incomplete—though more common—terms for the broader
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| − | phenomenon of acid deposition.
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| − | The effects of acid rain vary considerably with the vegetation, soil types, and weather conditions in a
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| − | given area. Under some conditions, the addition of sulfate and nitrate to the soil helps replace lost nutrients,
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| − | and aids plant growth. In other instances, however, acid deposition can cause lakes and streams to become
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| − | acid, damage trees and other plants, damage man-made structures, and help to mobilize toxic compounds
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| − | naturally present in soil and rocks. The countries of Northeast Asia have already begun to experience some
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| − | important impacts of acid rain. Forest health in some areas of the Koreas, China, and Japan has already
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| − | revealed evidence of degradation that points to acid rain124. Man-made materials such as zinc-plated steel
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| − | have drastically shorter-than-normal lifetimes in south China, and irreplaceable cultural landmarks made
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| − | of limestone and other substances are being degraded at an accelerating rate.
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