Planeamiento estratégico de reposicionamiento de la marca

The vast majority of the environmental and health effects of electricity are from the generation side, particularly when firing low-quality coal. Hydro-electric and natural- gas fired facilities have lower environmental impacts. Applying adequate safeguards have rendered nuclear power stations safe. Sections 8.5.1 and 8.5.2 briefly detail the health and environmental impacts of electricity generation facilities.

8.5.1

Direct health effects

In the case of oil- and coal-fired plants, a significant public health risk results from exposure to the large amounts of gaseous and solid wastes discharged in the combus- tion process. These emissions include SO2, CO, NOx, hydrocarbons, and polycyclic organic matter. Coal-fired stations also discharge fly ash, trace metals, and radionu- clides. The presence of these pollutants leads to increased incidence of respiratory disease, toxicity and cancer. Disposal of the resulting solid waste leads to health risks

associated with leachate and groundwater contamination. Natural gas-fired plants pose a public health risk of NOxand particulate emissions, but are significantly less hazardous to health than oil- or coal-fired plants.

Renewable

Large-scale hydro-electric plants pose relatively few health risks compared with fossil-fired plants. However, still water reservoirs create ecological environments favourable to the spreading of parasitic and waterborne disease. Relatively low pub- lic risks exist from the low probability of dam failures. Biomass plants emit lower levels of SO2 compared with oil- or coal-fired plants, but have higher emissions of potentially carcinogenic particulates and hydrocarbons. Other renewables such as solar photovoltaic and thermal, geothermal, tidal, and wind power, pose no significant occupational or health risks at the generation stage.

Transmission and distribution

The health impacts of transmission and distribution, particularly ultra high voltage alternating current (UHVAC) and high voltage direct current (HVDC), are well docu- mented [11]. It has been verified that human sensitivity to short-term exposure to a strong electrostatic field could be significant. Studies to measure the biological effects of electric fields and of chronic exposure to electric fields on people, animals and plants have been carried out. Since 1981 dozens of studies examined the incidence of cancer among workers exposed to electric and magnetic fields (EMF). Results were inconsistent. While some studies showed a slight rise in mortality of leukaemia or brain cancer among electrical workers others showed no such tendency. Recent more extensive and detailed studies and research were also inconclusive. Any negative health effects of transmission and distribution may be relatively minor compared to the health effects of the alternative option: siting power generation facilities closer to population centres [12].

8.5.2

Environmental impact

As mentioned earlier, pollution resulting from electricity generation can be broadly categorised as having local, regional, and global environmental consequences. Regional and global impacts are caused primarily by the emission of atmospheric pollutants that have longer residence times, causing dispersal over larger areas. Most important among these gases are SO2, which causes acid deposition or ‘acid rain’, and CO2, which is a ‘greenhouse gas’ and can contribute to global warming. Local impacts

Purely local impacts include those caused by fossil-fired power plant emissions to the atmosphere (particulates, leaded compounds, volatile organic compounds, dust) that result in air quality degradation causing damage to crops, structures, local ecosystems and posing a health hazard. This is also the case with emissions from waste-to-energy plants. Effluent disposal from fossil-fired and nuclear plants can

lead to groundwater contamination with long-term irreversible pollution implications. The existence of potential carcinogens and mutagens in the waste can have negative impacts on health and agricultural productivity. Improper disposal of radioactive waste from nuclear plants (e.g. discharge of liquid waste into the sea) can cause destruction of fisheries and other health hazards through contamination of the water supply.

Hydro-electric power generation is perhaps the one electricity generation system that has only local, but occasionally major, environmental consequences. These con- sist of the damage caused by dam construction: destruction of habitats and loss of local/national biodiversity, the inundation of productive land and forests, and possi- bly the loss of cultural sites and mineral resources. Watershed disturbance sometimes leads to increased flooding and low flow in the dry season. On major river systems, this can have inter-regional and/or transitional consequences causing significant polit- ical and social unrest over water rights. The existence of still water contributes to the spread of waterborne and parasitic disease. The massive displacement of people that is often required represents a significant social cost and can lead to increased use of marginal lands.

Environmental impacts from other renewables are related primarily to the loss of land use represented by the high space intensity of solar energy, and the noise caused by wind-powered generation.

Regional impacts

Coal- and oil-fired power stations emit significant amounts of sulphur dioxide and nitrogen oxides to the atmosphere. The transport of sulphur dioxide occurs over long distances (greater than 1000 km), causing the deposition of emission products over national boundaries. This may result in ecologically sensitive ecosystems receiving depositions of sulphur well above carrying capacity.

Acid deposition caused by sulphur and nitrogen oxides results in damage to trees and crops, and sometimes extends to acidification of streams and lakes, resulting in destruction of aquatic ecosystems. It also leads to the corrosion, erosion, and discolouration of buildings, monuments and bridges. Indirect health effects are caused by the mobilisation of heavy metals in acidified water and soil.

While electricity generation accounts for less than half of the total anthropogenic nitrogen oxide emissions (the majority of the remainder is caused by motor vehicle exhausts), the portion of SO2emitted by electricity generation is substantial. For example, Europe (including Eastern Europe) emitted close to a third of the worldwide anthropogenic sulphur emissions in the early 1980s. It is estimated that in 1985, 60 per cent of European SO2emissions were the result of electricity production.

Other regional environmental impacts are caused by radiation effects on health, and land/water contamination caused by severe nuclear accidents. As mentioned before, changes in hydrological flow and water conditions caused by dams can also have regional consequences. Thermal-power plants could also have a negative effect on aquatic organisms, fisheries, etc., owing to the water temperature increase that could be caused by diffused thermal effluent.

The relative contribution of electricity generation to the prospects of overall global warming (mainly in the form of CO2emissions) has been estimated at about 20 per cent till now, but rapidly increasing, compared with about 7–8 per cent caused by deforestation. Of the contribution of fossil fuels, coal and oil each contribute about 40 per cent of anthropogenic CO2emissions, and gas contributes about 15 per cent. OECD and other European countries account for about 70 per cent of global fossil fuel CO2emissions at present. However, energy consumption as a whole is the single largest contributor to greenhouse gas emissions in developing countries. Both India and China will be forced to increase coal-fired generation to meet the growing energy needs of their citizens for electricity through utilising domestic energy sources; some of this coal is low quality with enormous local, regional and, maybe, global impacts.

8.6

Investment costs in reducing dangers