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12003 FEE > Power Systems > Flashcards

Power Systems Flashcards

1
Q

What is solar power?

A

Energy from the thermo-nuclear reactions of the sun.

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2
Q

What is photovoltaics?

A

The generation of voltage/ current when a photovoltaic cell is exposed to light

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3
Q

How are solar modules composed?

A

LOOK AT THE DIAGRAM IN NOTES

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4
Q

What is open circuit voltage used for?

A

Voc is used to measure the voltage output of a solar module

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5
Q

What is short circuit current used for?

A

Measures the maximum current that flows out of a solar module

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6
Q

What is the max power point?

A

Pmax = Imax x Vmax

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7
Q

What effect does sun irradiance have on panel current and voltage?

A

No (minimal) effect on voltage
as irradiance decreases current decreases

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8
Q

What effect does temperature have on the efficiency of a solar panel?

A

As the temperature increases, the efficiency decreases

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9
Q

What happens I and V of solar panels in series?

A

Add the V and I remain constant

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10
Q

What happens to the I and V for solar panels in parallel?

A

V remains constant and add the Is

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11
Q

What happens to parallel panels with different voltages?

A

total V would be the same as the lowest
sum the currents

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12
Q

What is a stand-alone system?

A

A system that operates independently from the grid (see diagram)

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13
Q

What is a hybrid system?>

A

That uses personal solar panels and the grid for energy supply

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14
Q

What is a grid system?

A

Use of large solar panel farms for energy supply

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15
Q

What are the steps for system creation?

A

( Just look in the notes this isn’t flash card possible)

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16
Q

What is wind power?

A

The conversion of kinetic energy from the wind into electrical work

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17
Q

What is a HAWT?

A

Horizontal axis wind turbine where the rotating axis is parallel to wind stream

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18
Q

+ves of HAWT?

A

High aerodynamic efficiency
More power produced per unit
Low cost per unit of output

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19
Q

What does the pitch system do?

A

Makes sure the pitch (angle of the blade) is optimal for efficient energy transfer

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20
Q

What does the yaw do?

A

Turns the turbine towards the wind

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21
Q

What is an upwind HAWT?

A

The wind hits the blades first
(diagram may help)

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22
Q

What are the -ves of an upwind HAWT?

A

higher bending loads
higher rotor mass
more blade damage
requires a yaw

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23
Q

What is a downwind HAWT?

A

Wind doesn’t hit the blades first.

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24
Q

What are the benefits of a downwind HAWT?

A

It doesn’t need a yaw.

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25
Q

What is stalling?

A

Changing the angle of the blades to limit the output

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26
Q

What is furling?

A

The blades are completely turning out of the wind to stop them

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27
Q

What is the purpose of both furling and stalling?

A

Used @ high wind speeds to stop damage to a turbine (probs safety too)

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28
Q

What is a VAWT? (see diagram)

A

Vertical Axis Wind Turbine, where the rotating axis is perpendicular to the group

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29
Q

What are the benefits of the VAWT?

A

It accepts all wind directions
It doesn’t need a yaw
Simpler
Cheaper per individual unit

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30
Q

What is the Bertz Limit?

A

The maximum efficiency of a turbine @59.3%

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31
Q

What does windpower depend on?

A

Area
Air density
Wind speeds
Pitch angle (control factor 1)
Tip speed (control factor 2)

32
Q

How does height affect wind turbine output?

A

As you get higher the wind speed increases which would increase power output
however
As you get higher the air density decreases exponentially, which reduces power output

33
Q

What makes finding a tip speed ratio difficult?

A

It must be varied to maximise efficiency as only 1 ratio is most efficient for 1 wind speed

34
Q

What is capacity factor?

A

CF = (energy generated in a year) / (max possible energy generated)

35
Q

What is a good approximation of the capacity factor?

A

0.0087 * v (avg) - Power rating / (diamter)^2

36
Q

How much energy is in 1 ton of oil ( 1 toe)

A

42GjJ

37
Q

What are the thermodynamic laws?

A

Conservation of energy

Entropy of interacting systems never reach 0 (whatever this means)

38
Q

How does a conventional thermal station work?

A

Use of fossil fuels to evapourate water in order to turn a turbine

39
Q

How does a nuclear power station work?

A

Use of a nuclear fission to evapourate a water to turn a turbine

40
Q

What are the 3 types of nuclear power plants? (their names describe what they do)

A

Pressurised water reactor
Pressurised heavy water reactors
Boiling water reactors

41
Q

What is a combined cycle gas turbine?

A

A facility that generates electricity by using both a gas turbine and a steam turbine to make the most of the heat produced during the process.

42
Q

How does a combined cycle gas turbine work?

A

It uses the wasted heat to boil more water which is then passed through a turbine

43
Q

What is HEP?

A

The use of water in a dam to turn a turbine

44
Q

What are the +ves of HEP?

A

It is renewable
It has a predictable output
It lasts long without needing replacement

45
Q

What are the -ves of HEP?

A

Geography (needs a dam and needs to be transported)
Causes river damage

46
Q

What is pumped storage HEP?

A

Pumping water into a higher place (so it has potential energy) and releasing it to turn a turbine when energy demands require it

47
Q

What are the -ves of pumper storage HEP?

A

It causes a net energy loss

48
Q

What is carbon capture and storage?

A

Capturing carbon dioxide and storing it in geological formations

49
Q

What is the -ve of Carbon capture and storage?

A

It reduces green house gasses emitted into the atmosphere

50
Q

What is the -ve of Carbon capture and storage?

A

Depends of geography
Requires more fuel

51
Q

What is combined heat and power?

A

A conventional thermal station that recycles waste steam for it to be used for heating. (combines thermal energy for heating and electrical energy)

52
Q

What is wave power?

A

The use of waves to turn a turbine

53
Q

+ves of wave power?

A

Low environmental impact

54
Q

-ves of wave power?

A

hard to reach 50hz requirements
breaks in storms

55
Q

What is tidal energy?

A

The use of gpe from the moon to move tides through a generator

56
Q

What is the load factor?

A

The actual amount of energy (KWh) delivered by a system in a period of time.

57
Q

What is domestic load?

A

Energy consumed by households

58
Q

How do domestic loads vary?

A

Less than commercial and more than industrial @ 30 - 60% usage

59
Q

What is commercial load?

A

The energy consumed by commercial businesses for things like lighting and heating.

60
Q

How does commercial load vary?

A

The most out of the 3. 20-80%

61
Q

What is industrial load?

A

Energy consumed by small, medium and large called industries?

62
Q

How does industrial load vary?

A

90%+ all the time

63
Q

What are some examples of resistive loads?

A

Lights, heaters, toasters

64
Q

Examples of inductive loads?

A

Washing machines
Fridges
Air con

65
Q

Look at load duration curves

A

YESS SIRR

66
Q

What are tariffs?

A

The rate at which energy is supplied to consumers

67
Q

What is the role of tariffs?

A

Return on investment for suppliers
Fair to consumers
Simple

68
Q

What are the 4 types of tariffs we need to know?

A

Simple, flat rate, two-part and three-part.

69
Q

What is the Price elasticity of demand?

A

%Δdemand/ %Δprice

70
Q

What is perfect elasticity?

A

Infinite change in demand at any given price

71
Q

What is elastic demand?

A

When a %change in price leads to a greater %change in demand

72
Q

What is unitary demand?

A

When the %change in price and %demand are the same

73
Q

What is inelastic demand?

A

When a %change in price leads to a smaller %change in demand

74
Q

What is perfect inelastic demand?

A

When a change in price has no effect on demand

75
Q
A

12003 FEE (4 decks)

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