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). CO’s
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.
