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ENGR 202 > Electric Power Plants > Flashcards

Electric Power Plants Flashcards

1
Q

At what point of the energy cycle is electricity often pollution free and environmentally friendly?

A

Electricity use.

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2
Q

Overall power plant efficiency (nElec) is given by what ratio?

A

Useful electrical energy output / total energy input.

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3
Q

Electrical energy is commonly expressed in what units?

A

Kilowatt-hours (kW-hr)

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4
Q

Electrical power is commonly expressed in wattages of what (2) magnitudes?

A

Kilowatts (kW) or megawatts (MW)

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5
Q

How many kW are there in a single MW?

A

1000 kW = 1 MW

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6
Q

What term is used to refer to the energy per unit mass of fuel (kJ/kg)?

A

The heating value.

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7
Q

Energy comes mainly from what two elements in fossil fuels?

A

Carbon and hydrogen.

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8
Q

What about the chemical compositions of coal, oil, and natural gas explains their different heating values?

A

They differ in the proportions of hydrogen and carbon.

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9
Q

Which bonds are broken within fossil fuels, causing the release of chemical energy?

A

Atomic bonds between carbon and hydrogen atoms.

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10
Q

The amount of environmental contaminants that are released by a plant depends on what?

A

The quantity of fuel burned.

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11
Q

The environmental concerns about fossil fuel power plants center primarily around which 4 atmospheric emissions?

A

Carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides, and particulate matter (PM).

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12
Q

Which form of fossil fuel leads to highest level of sulfur impurities?

A

Coal - which undergoes little or no processing for sulfur removal.

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13
Q

Oil contains sulfur compounds when extracted from the ground.

A

True.

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14
Q

Natural gas contains sulfur compounds when extracted from the ground.

A

True.

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15
Q

Why doesn’t oil and natural gas emit much sulfur dioxide when burned?

A

These impurities are removed in oil refineries and by gas treatment, respectively.

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16
Q

When coal is burned, how much of the sulfur is retained in the solid ash particles?

A

2% - 5%

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17
Q

When coal is burned, how much of the sulfur is oxidized to gaseous SO2?

A

95%+

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18
Q

What percentage of the SO2 formed during combustion may be further oxidized to SO3?

A

Less than 1%.

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19
Q

Why is SO3 harmful?

A

SO3 reacts with water vapor in the combustion of gas to form gaseous sulfuric acid (H2SO4).

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20
Q

What 2 primary nitrogen oxides (NOx) form from fossil fuel combustion.

A

Nitric oxide (NO) and nitrogen dioxide (NO2).

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21
Q

How do nitrogen oxides form?

A

From high-temperature reactions between oxygen and nitrogen.

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22
Q

Nitrogen oxides’ environmental impacts are significant because they constitute a large fraction of total combustion products.

A

False - although they are significant, they constitute a small fraction of combustion products.

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23
Q

What solid waste arises from coal-burning plants?

A

Ash

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24
Q

What is the primary reason coal-burning plants generate water waste?

A

Water is often used to transport collected ash within the power plant.

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25
Q

What is the secondary reason coal-burning plants generate water waste?

A

Due to the discharge of waste heat to a body of water.

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26
Q

Which step in the fossil fuel life cycle remains a source of land use impacts and disturbances?

A

Resource extraction process (coal mining, drilling for oil and natural gas).

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27
Q

Name a land use disturbance associated with the transport of natural gas.

A

Leakage of gas from pipelines.

28
Q

Name a source of environmental impact associated with the transport of electricity.

A

Transmission and distribution lines that carry electricity from power plants to customers.

29
Q

Fission is a nuclear reaction that splits what?

A

The nucleus of an atom splits into two smaller nuclei - releasing a significant amount of energy in the process.

30
Q

How may a fission reaction be involved in a chain reaction?

A

The neutrons released during fission go on to initiate further fission reactions.

31
Q

What is the result of a nuclear power plant that fails to maintain a controlled chain reaction?

A

An uncontrolled release of energy results in a nuclear meltdown or explosion.

32
Q

What two types of radioactive waste are produced by nuclear power plants?

A

Low-level waste & high-level waste.

33
Q

Until when is LLW stored at nuclear power plants?

A

Until it is no longer radioactive, or there is enough to send to a LLW disposal site.

34
Q

Where is HLW stored?

A

High-level waste must be stored in specially designed storage containers and facilities.

35
Q

HLW from nuclear plants consists primarily of what?

A

Highly radioactive spent (used) nuclear fuel assemblies.

36
Q

Name 6 sources of renewable energy.

A

Hydroelectric, wind, biomass, waste, geothermal, and solar energy.

37
Q

List 3 basic approaches to reduce the environmental impacts of power plants.

A

End of pipe treatment, green design, and selecting cleaner energy sources & alternative technologies.

38
Q

Describe the end of pipe treatment.

A

Technological measures to control or remove a pollutant before it is released to the environment.

39
Q

The end of pipe treatment is more desirable than pollution prevention appraoches.

A

False.

40
Q

When is the application of green design principles most fruitful?

A

When designing new facilities.

41
Q

Green design also includes pollution prevention approaches, such as?

A

Innovations that produce useful by products rather than solid wastes.

42
Q

Ash is the solid residue that results from burning what?

A

Solid fuels such as coal, biomass, and municipal solid waste.

43
Q

Define bottom ash.

A

The largest particles that collect at the bottom of the combustion chamber of power plant boilers.

44
Q

Define fly ash.

A

Smaller and lighter particulates that collect in air emission control devices.

45
Q

Define ash sludge.

A

Ash mixed with water.

46
Q

What type of fossil fuel plants store ash sludge?

A

Coal-fired power plants.

47
Q

Where do coal-fired power plants store ash sludge?

A

Retention ponds.

48
Q

Retention ponds pose risks to surface water.

A

False - ground water.

49
Q

When do retention ponds cause extensive damage and pollution downstream?

A

When they burst.

50
Q

Besides retention ponds, what two things do coal-fired power plants do with ash?

A

Send to landfills or sell for use in making concrete blocks or asphalt.

51
Q

Which is the oldest and most noticeable form of air pollution from coal combustion?

A

The emission of fly-ash or soot particles.

52
Q

How does an electrostatic precipitator (ESP) remove particles from a gas stream?

A

By using electrical energy to charge particles either positively or negatively, which are then attracted to collector plates carrying the opposite charge.

53
Q

Which is the major water pollutant associated with steam electric power plants?

A

Thermal pollution.

54
Q

Waste heat from which part of the power plant is typically transferred to cooling water drawn from a nearby stream, or river?

A

The power plant condenser.

55
Q

Due to regulations prohibiting dumping of waste heat to bodies of water, how is waste heat disposed of by steam electric power plants?

A

Waste heat is transferred to the atmosphere using a cooling tower.

56
Q

What categories of water pollutants originate mainly from the ash collected at coal-burning plants?

A

Suspended solids, acidity, and heavy metals.

57
Q

How is ash transported to a disposal site in most plants?

A

Ash is continuously collected and mixed with water.

58
Q

How does ash lead to trace metal contamination of ground water?

A

The leaching of metals from the bottom of an ash pond.

59
Q

Ash ponds are constructed with what 3 impermeable layer of natural or synthetic materials to prevent the infiltration of contaminants into the ground?

A

As clay, compacted soil, or rubber linings.

60
Q

List 3 techniques to improve power plant energy efficiency.

A

Increased operating temperatures, cogeneration, advanced cycles.

61
Q

Why do power plants operate below the theoretical maximum efficiencies?

A

The maximum temperature of the power generation cycle is limited by material available for boilers and turbine blades.

62
Q

What is cogeneration?

A

The practice of recovering condenser heat for some useful purpose.

63
Q

Cogeneration systems typically increase the efficiency of fuel utilization by what percentage?

A

70% - 80%

64
Q

When are cogeneration systems effective?

A

When there are simultaneous demands for both heat and power in the proportions delivered by the system.

65
Q

Name 2 types of advanced cycles.

A

Integrated Gasification Combined Cycle, Integrated Gas Turbine Fuel Cell.

ENGR 202 (8 decks)

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