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