This set of Energy Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Environmental Aspects of Power Generation”.
1. Power generation facilities have been affected by the concern for the _______
b) Availability of resources
c) Soaring costs
Explanation: The design, location, construction and operation of electrical power generation facilities have been affected by the concern for the environment. Hence power engineer must have concern for the environment while producing enough power to meet public demand at low cost. Government has passed environmental legislation that limits amount of pollutants that can be discharged to the environment.
2. How many forms of sulfur exist in the atmosphere?
Explanation: Sulfur in the atmosphere exists in three (3) forms:
i. Sulfur dioxide, SO2 which comes from artificial causes.
ii. Hydrogen sulfide, H2S which comes from natural causes.
iii. Various sulfates, coming from sea spray and oxidation of SO2.
3. How much amount of sulfur dioxide is caused in the atmosphere?
b) 50% <SO2>50%
Explanation: Although sulfur dioxide is caused by artificial causes, it is primary concern since it contributes <25% of all sulfur in the atmosphere. It is estimated that more than 90 million tons of sulfur dioxide are discharged into the atmosphere every year.
4. Acid rain is caused mainly by ___________
a) methane gas
b) sulphuric acid
c) sulfur dioxide
d) carbon dioxide
Explanation: Acid rain and acid snow are caused by mainly by sulfur dioxide and also oxides of nitrogen and other sulfur oxides contribute fewer amounts to it. These gasses carried along wind currents combine with water molecules in the water vapor of the atmosphere, forming tiny drops. These drops when encountered by snow or rain producing clouds, results in acid rain.
5. Acid rain affects tree and plants.
Explanation: Acid rain does affect trees and plants. It results in leaching of essential plants nutrients from the soil and reduces nitrogen fixation by microorganism. This makes soil less fertile. Also dissolve aluminum and cadmium out of soil minerals, allowing them to enter roots and kill trees.
6. By what type of reaction are Nitrogen oxides caused?
a) Endothermic reaction
b) Combustion reaction
c) Exothermic reaction
d) Synthesis reaction
Explanation: Production of nitrogen oxides is an endothermic reaction and its concentration is temperature dependent. NOx emissions can be reduced by lowering the combustion temperature and by eliminating hotspots in the furnace.
7. Which among the following oxides are major contaminants in the atmosphere?
a) Nitrogen oxides
b) Oxides of carbon
c) Sulfur oxides
d) Particulate matter
Explanation: Oxides of carbon such as CO, CH4 and CO2 are major contaminants in the atmosphere. Carbon monoxide is caused by natural causes partially, such as marsh gas, coal, vegetation and forest fires. This contribution is small compared to human generated causes. 90% of CO is produced by motor vehicles, where as power plants contribute less than 1%. The total amount of CO produced per year is 230 million tones.
8. Carbon dioxide (CO2) is largely contributed by __________
b) power plants
Explanation: Carbon dioxide is largely contributed by power plants. CO2 added to nature by natural causes viz., decay of organic matter contributes more than that by artificial causes. Also CO2 contaminants in atmosphere are not considered as pollutants as it is essential for plants.
9. By which process can CO2 be removed from the atmosphere?
Explanation: Carbon dioxide (CO2) can be removed by the process of photosynthesis. This process concerts back CO2 into oxygen and organic compounds in the presence of sunlight and water. However, more concentration of CO2 results in green house effects.
10. What causes green house effect?
a) Carbon dioxide
b) Carbon tetra oxide
Explanation: CO2 causes green house effect. The concentration of CO2 has increased to a level beyond the capacity of plant life and the oceans to completely remove it. 50% of CO2 added is retained in the atmosphere. And this retained CO2 causes green house effect.
11. In what form are the radiations coming from sun?
a) Long waves
b) Short waves
c) Transient waves
d) Longitudinal waves
Explanation: The atmosphere, analogous to the glass panes of green house, transmits the radiation from the sun. The surface of sun is about 6000k and most of the radiation is in the form of short waves and visible portions of the spectrum, and only a portion of the radiation is absorbed or scattered back to the space by atmosphere.
12. What causes absorption of infrared radiations?
a) Large contents of CO2 and H2O
b) Sulfur oxides
d) Earth gravity
Explanation: The presence of CO2 and H2O in the atmosphere results in the absorption of large portions of infrared radiations from the surface and partial of those radiations back to earth. Thus atmosphere us not transparent completely to the reradiated energy and traps much of the energy from the sun.
13. What is the reason for melting of polar caps?
a) Increasing levels of sulfur
b) Depletion of ozone
c) Increasing levels of CO2
d) Longitudinal radiation
Explanation: The growing levels of concentration of CO2 increase the surface temperature of earth. This may result in climatic changes with disastrous consequences, such as melting of polar ice caps and rising of sea levels.
14. What are the constituents of particulate matter?
a) Fluid gases
b) Smoke and dust
c) Flue gas
d) Poisonous gases
Explanation: Particulate matter is composed of smoke, and other solids of variety of organic and materials. Both natural and human activities are responsible for the particulate matter in the atmosphere. These are the basic causes for the formation of smog and fog.
15. What is TDI stands for in the Thermal pollution field?
a) Turbocharger direct injection
b) Toluene Diisocyanate
c) Thermal energy discharge integration
d) Thermal discharge index
Explanation: To compare power generating systems with respect to the amount of thermal energy discharged to the environment a term is introduced, known as thermal discharge index (TDI). The thermal discharge index of any power system is the number of thermal energy units discharged to the environment of each unit of electrical energy produced by plant.
Sanfoundry Global Education & Learning Series – Energy Engineering.
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