Science 30 January 1999 Grade 12 Diploma Examination

Sample Answer – Long Answer 2The main methods of electrical energy production are coal-fired, nuclear, and hydrogenerating power stations. The main environmental problems associated with the use offossil fuels such as coal are global warming and acid deposition. The carbon dioxideproduced by combustion causes a greenhouse effect in the atmosphere. Some scientiststhink that this will lead to disastrous changes in global climate and may cause widespreaddeath to many species including humans. Acid deposition is caused when sulphur oxidesand nitrogen oxides react with moisture in the air. This is causing the destruction ofmany terrestrial and aquatic habitats around the world. Leaching of heavy metals intowater habitats and thermal pollution are also problems associated with fossil fuelpoweredstations.Nuclear power production produces long-lasting radioactive wastes. Safe disposal ofthese wastes over thousands of years is not possible presently. Background radiation maycontinue to rise to catastrophic levels if accidents at power plants occur or if radioactivewastes leak into the environment. Not only will the organisms on which we rely forsurvival be affected, but many human deaths due to cancer will occur.While hydro power produces few contaminants it produces significant environmentaleffects. Damming a river causes flooding of the upstream part of the river. This changesthe habitats and displaces many kinds of plants and animals. It may also cause moreheavy metals to leach into the water. Silting may cause changes in the drainage patternsthroughout the area around the dam.Alternate forms of electrical energy such as photovoltaic cells, wind generators, tidalpower, and geothermal power stations have fewer environmental effects. Thedisadvantages of these power sources is the cost of building and maintaining theequipment necessary to run them, and in some cases, they are available in a limitednumber of places.The main strategy for the immediate future should be to reduce the consumption ofenergy. This can be done by educating people about the effects of energy production onthe environment. It might be necessary to lower our expectations for some of the luxuriesthat we now enjoy. People should be taught methods of conserving energy. Increasingthe cost of using energy might also be implemented by taxing excessive energy use.Besides reducing energy use, it is also necessary to develop cleaner ways of producingenergy. Development of technologies such as solar energy, wind, tidal, and geothermalpower stations should have a high priority. Nuclear fission may also provide a relativelyclean form of energy in the future.