Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Renewable energy > Final > Flashcards

Final Flashcards

1
Q

A cost-effective micro-CHP system should be:

A

run constantly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The efficiency of a large-scale fossil fuel burning power plant not utilizing CHP would likely be closest to:

A

40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The majority of the distributed generation units in the U.S. today are:

A

small fossil fuel generators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the primary purpose of the buffer tank in a micro-CHP system?

A

to temporarily store all of the thermal energy produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is usually the biggest problem to overcome in designing an economically viable micro-CHP system?

A

low heat demand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which of the following buildings would be the best candidate for micro-CHP?

A

dormitory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which of the following conditions are usually found where large-scale CHP exists?

A
  • colder climate
  • the need for electricity
  • higher building density
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which of the following is most accurate regarding PURPA?

A

PURPA forced the utilities to allow Independent Power Producers to connect to the grid.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which of the following would not be an economically viable use for the thermal energy produced by micro-CHP?

A

cooking stove

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why is CHP not utilized at most large-scale U.S. power plants?

A

The power plants are remotely located.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the abbreviation used to describe the simultaneous production of both electricity and heat from a single fuel source?

A

CHP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The primary advantage of a typical micro-CHP unit is that it does not use any fossil fuel.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A dam has a spillway to prevent what?

A

overtopping

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

A large hydro plant with an inconsistent water supply would likely have a:

A

low Capacity Factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Advanced Hydropower strives to achieve what at an existing dam site (choose all that apply)?

A

higher environmental performance and higher electrical output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Itiapu Dam (India) has a capacity of 14 GW. Approximately how many average sized coal power plants is that equivalent to?

A

20

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

The biggest obstacle to the dam removal movement is:

A

lack of money

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

The highest percentage of U.S. electricity that hydro achieved was approximately:

A

40%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

To get from the intake to the turbine water flows through the:

A

penstock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which of the following parts of a dam is not an electrical component?

A

turbine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which of the following statements is most true today?

A

Hydro produces 60% of U.S. renewable energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How much electricity per year, in TWh, will a 700 MW hydro plant produce if it operates with a capacity factor of 25%? Provide only the number.

A

1.533

(x TWh / (700 MW * 8760 hours) = x / 6,132,000 MWh = 0.25 or 25% capacity factor

x = 6,132,000 MWh * 0.25 capacity factor = 1,533,000 MWh = 1.533 TWh)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Most dams in the U.S. produce power.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

North Carolina is part of the Tennessee Valley Authority Coalition.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Pumped Storage Hydro creates more electricity than it uses to operate.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In order to produce electricity a micro-hydro site needs which two characteristics?

A

water flow and pressure head

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Which type of turbine must be used on a site with a head of less than 10 feet but with adequate flow?

A

Reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The maintenance on a micro-hydro system is most significantly related to:

A

the amount of water handled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

The most difficult part of a micro-hydro system installation with significant capacity will usually be the:

A

penstock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What function does a dump load perform in a micro-hydro system?

A

It diverts power to something else when there are no operating loads.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the static pressure of a penstock that has 175 feet of head?

A

76 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

When a full penstock begins to flow the pressure at the outlet of the pipe will:

A

fall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

When does the maximum flow rate in a penstock occur?

A

when net pressure is 2/3 static pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Where should a powerhouse be placed in a micro-hydro system?

A

as close to the water return as possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which of the following is required on both a DC and an AC off-grid micro-hydro system?

A

dump load

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Which of the following pipe materials would you likely use for the bottom portions of a penstock under very high pressure?

A

steel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Given a wind shear exponent of 0.14 and an average wind speed of 14mph at 35 feet, what will the approximate wind speed be at a turbine height of 60 feet?

A

15mph

((60/35)0.14 x 14 = 15.09mph)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

The causes of wind turbine noise include which of the following? Select all that apply.

A

mechanical operation and aerodynamics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The minimum size of a site for a small turbine should be:

A

1 acre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

The most important factor in power production by a wind turbine is:

A

wind speed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

The U.S. state with the highest wind energy capacity is:

A

Texas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Which of the following would likely be the best site to locate a wind turbine?

A

a site with constant high winds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What country is the leader in installed wind turbine capacity?

A

China

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

The capacity of a wind turbine indicates the amount of power produced whenever the wind blows.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

The U.S. has a higher wind capacity factor than solar PV.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Wind turbines cause more bird deaths than every year than pollution, buildings, and cats combined.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

A barrage tidal generation plant is closest in terms of technology to a:

A

hydroelectric dam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

All other things being equal, which of the following wind turbines will likely produce the largest annual energy output?

A

rated output of 1 kW at a rated wind speed of 20 MPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Based on wind speed, on a site of which Wind Power Class would be the best to build a wind turbine?

A

Class 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Currently, most distributed generation units in the U.S. are:

A

fossil fuel generators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

If the static pressure in a microhydro penstock is 100 psi, the optimum net pressure for maximum flow will be closest to:

A

70 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

In terms of wind power, the U.S. is the world leader in:

A

electricity produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

On which of the following sites could a vertical-axis wind turbine be considered over a horizontal-axis turbine?

A

on a tight urban lot with severe noise restrictions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

The largest hydro capacity in the U.S. is found in which region?

A

Pacific Northwest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

The largest source of renewable electricity in the world is:

A

hydroelectricity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

The maintenance on a micro-CHP unit is most similar to the maintenance on a:

A

car engine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is a primary advantage of an AC microhydro system over a DC system?

A

smaller wire sizes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What is the approximate swept area of a horizontal-axis turbine with a rotor diameter of 16 feet?

A

201

(swept area = πr2, so
3.14159 * (8)2 = 201.06)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What is the capacity factor of a hydroelectric dam with an installed capacity of 1,000 MW producing 180,000 MWh in a 30-day month?

A

25%

180,000 MWh / (30 days * 24h per day * 1,000 MW) = .25 or 25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What is the most common means of rotor control for small wind turbines?

A

horizontal furling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is the most effective way to stop a small wind turbine from spinning out of control?

A

During a break in the wind, apply dynamic braking.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the most important consideration when selecting a small wind turbine?

A

annual energy output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What is the purpose of a tail vane on a wind turbine?

A

to passively yaw the turbine into the wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the static pressure in a microhydro penstock with a head of 300 feet?

A

130 PSI

The static pressure is the highest pressure achieved at the bottom of the penstock when it is full of water and not moving. 2.31 vertical feet of head is equal to 1 PSI of pressure. Therefore:

300 / 2.31 = 130 PSI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

When designing a microhydro system, which of the following will likely result from an increase in the flow of intake water?

A

increased intake maintenance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

When does the dump load kick in on a stand-alone DC microhydro system?

A

whenever the battery bank is fully charged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Which is the largest hydroelectric dam in the world?

A

Three Gorges Dam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Which of the following are an advantage of hydroelectric dams over other forms of energy generation from renewable sources? Select all that apply.

A

Systems have an ability to provide both baseload power and peak power., Power production scales exponentially., Systems generate electricity using one of the most abundant chemicals on earth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Which of the following are an advantage of microhydro over other forms of energy generation from renewable sources? Select all that apply.

A

Power production scales exponentially., Systems generate electricity using one of the most abundant chemicals on earth., Systems can be configured and installed in a DIY fashion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Which of the following are an advantage of wind turbines over other forms of energy generation from renewable sources? Select all that apply.

A

Power production scales exponentially., Systems can be configured and installed in a DIY fashion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Which of the following are likely to be found on a large wind turbine but not on a small wind turbine? Select all that apply.

A

transmission, yaw motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Which of the following are the primary goals of Advanced Hydropower? Select all that apply.

A

increase power capacity, increase environmental performance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Which of the following buildings is the best candidate for a micro-CHP generator?

A

a hotel with a natural gas supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Which of the following countries is not among the world leaders in large wind turbine manufacturing?

A

the United Kingdom (UK)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Which of the following is an advantage of combined heat and power (CHP)?

A

Systems burns fossil fuels more efficiently.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Which of the following is an advantage of tidal generators over other forms of energy generation from renewable sources?

A

Systems harness natural cycles that occur twice per day.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Which of the following is not a characteristic of a self-supporting wind turbine tower?

A

It is less expensive than a guyed tower.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Which of the following is not an advantage of offshore wind?

A

proven reliability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Which of the following power plant types is always built as a baseload plant?

A

nuclear plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Which of the following renewable technologies is a viable large-scale alternative to hydroelectric power?

A

wind turbines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Which of the following sites would be the best candidate for significant power production using microhydro?

A

Head: 180 feet, Flow: 60 GPM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Which of the following technologies will likely have the highest capacity factor?

A

hydroelectric dam

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Which of the following would need to be increased in order to create the most significant increase in the power of a wind turbine? Select all that apply.

A

wind speed, rotor area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Which renewable energy source creates the most electricity in the United States?

A

hydroelectricity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

You want to install a Southwest Windpower Air X turbine on your 1-acre lot. Your house is 30 feet tall and there are no trees on the lot. You want to order the shortest tower that will still get your turbine into the unobstructed winds. Which of the following towers should you order?

A

75 feet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

A hydroelectric dam can be easily turned off and on quickly to provide spot electricity.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

A microhydro site with high head would most likely use an impulse turbine.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

A pumped hydro storage plant pumps uphill when grid demand is high and produces power when grid demand is low.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

All areas off the coast of North Carolina are available for offshore wind turbine development.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

An effective wind turbine uses more lift than drag to turn its rotor.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

CHP is not utilized at most large-scale U.S. power plants because the power plants are remotely located.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Most dams are built to create electricity.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

Most large utility-scale wind turbines have a tail vane.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Most large-scale U.S. power plants utilize CHP.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

A machine that extracts heat from ground water and transfers it to domestic hot water is called a:

A

water-to-water heat pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

How many coaxial coil heat exchangers are located in a water-to-air ground source heat pump equipped with a desuperheater?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

In a geothermal heat pump the coaxial coil heat exchanger replaces what?

A

the outdoor coil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

In North Carolina, if the outdoor air temperature in summer is 85 degrees the ground temperature 6 feet below the surface will be:

A

cooler

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What is the primary advantage of an open loop over a closed loop in a geoexchange system?

A

more efficient heat exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

What is the primary reason why polyethylene pipe is used in a ground source closed loop?

A

The joints between the pipes are strong.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

What primarily determines the capacity of a horizontal ground loop (select all that apply)?

A

soil type, the length of the pipe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

What two qualities define an effective refrigerant (select all that apply)?

A

At low pressure it boils at a very low temperature., At high pressure it condenses at a very high temperature.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

Which of the following closed loop systems would be most appropriate for a condo in downtown Raleigh with a small accessible courtyard?

A

vertical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

Which of the following criteria define the best location for a ground source heat pump (select all that apply)?

A

moderate ground temperature, mixed climate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

Which of the following increases your HVAC load in the summer but not in the winter (select all that apply)?

A

lighting, humidity, solar gain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

A warm spring could be effectively be used to generate what?

A

district heat

106
Q

The Geysers uses treated wastewater to:

A

replenish the aquifer

107
Q

What will occur if the source aquifer of a geothermal energy plant is depleted?

A

The capacity of the plant will be reduced.

108
Q

Which of the following can be found in heated groundwater used for geothermal energy?

A

methane, dissolved metals, hydrogen sulfide, ammonia

109
Q

Which of the following is the least complicated type of geothermal energy plant?

A

dry steam

110
Q

Which of the following natural phenomena is not a visible source of geothermal energy?

A

aquifer

111
Q

Which of the following U.S. states has the largest geothermal energy potential?

A

Nevada

112
Q

Geothermal energy is a pollution free source of electricity.

A

False

113
Q

Compared to a gasoline-powered vehicle, a fuel cell vehicle using hydrogen from natural gas reforming is:

A

quieter, NOT carbon neutral, and costs more

114
Q

Hydrogen kept at -163ºF would be in the state of a:

A

gas

115
Q

Which of the following describes a possible relationship between a wind turbine and a fuel cell?

A

Excess electricity from the wind turbine can be used to create hydrogen to be used later by the fuel cell.

116
Q

Why is hydrogen liquefied?

A

to minimize its volume

117
Q

Hydrogen gas has a very high energy density.

A

False

118
Q

A 40-pound bag of wood pellets has a heat content of approximately:

A

340,000 BTU

119
Q

A face cord of wood is:

A

43 cubic feet

120
Q

A primary advantage of wood pellets over bulk dry wood for heating is:

A

consistency

121
Q

A site with severe groundwater quality issues should use which of the following types of geothermal loops?

A

vertical closed loop

122
Q

Advantages of fuel cells include which of the following? Select all that apply.

A

high reliability due to no moving parts, scalable, pollution-free

123
Q

Binary cycle geothermal energy plants can be considered:

A

less polluting than steam-based plants

124
Q

Biomass as a fuel source can be considered to be carbon neutral under which of the following conditions?

A

new planting replaces the harvested material

125
Q

Compared to oil and natural gas, uncompressed hydrogen has an energy density that is:

A

lower

126
Q

Four fuel cells stacked together would produce a voltage closest to:

A

3 volts

127
Q

Fuel cells can utilize which of the following inputs? Select all that apply.

A

biogas, propane, natural gas, hydrogen gas

128
Q

Heat always moves from:

A

hot to cold

129
Q

In terms of conversion to ethanol, select the answer that is in order from easiest to hardest to convert.

A

sugarcane, grains, cellulosic material

130
Q

In terms of energy content, lignin is most similar to:

A

coal

131
Q

In the evaporator of a heat pump the refrigerant is transformed into:

A

all gas

132
Q

North Carolina currently has the resources to easily meet which percentage of its energy needs with biomass?

A

10%

133
Q

Of the following, the primary problem preventing the widespread use of residential fuel cell units is:

A

cost

134
Q

Substituting 10% of gasoline with ethanol (making E10) will result in:

A

up to 20% worse fuel economy

135
Q

The component of a heat pump where heat is released to the ambient environment is called the:

A

condenser

136
Q

The United States produces more ethanol annually than:

A

Canada, China, India

137
Q

What component keeps the refrigerant moving in a heat pump?

A

compressor

138
Q

What is the most important reason why a geothermal ground loop needs to be sized correctly?

A

Because a geothermal loop cannot be easily changed

139
Q

What is the primary purpose of a desuperheater?

A

to provide hot water

140
Q

When do the electric heat strips on a heat pump turn on?

A

Whenever the heat pump cannot extract enough heat from the ambient environment to meet the heating load

141
Q

Which country in the world has the most installed geothermal energy electricity capacity?

A

United States

142
Q

Which country in the world produces the most electricity from geothermal energy?

A

United States

Slide 22 of the “Geothermal Energy” lecture notes that the US has the highest installed capacity in the world. I realize a lot of students chose Iceland; that was not included with the purpose of tricking you, but to help you understand the difference in scale.

143
Q

Which of the following are an advantage of biodiesel? Select all that apply.

A

can be made at home, availability of source material, biodegradable

144
Q

Which of the following are an advantage of fuel cells over other forms of renewable energy generation? Select all that apply.

A

Systems have an ability to provide both baseload power and peak power., Systems generate electricity using one of the most abundant chemicals on earth.

145
Q

Which of the following could be considered an energy crop?

A

trees

146
Q

Which of the following geoexchange systems is considered an open loop?

A

standing column well

147
Q

Which of the following heat pump systems would likely give the best performance at the lowest operating cost?

A

system sized for 100% of the heating load and 125% of the cooling load

148
Q

Which of the following is a byproduct of biodiesel?

A

glycerol

149
Q

Which of the following is a form of heat loss in a building?

A

conduction

150
Q

Which of the following is an advantage of geothermal heat pumps over other forms of energy generation from renewable sources?

A

Systems might be cost-effective on almost every home in the United States.

Remember that the temperature of the ground at the depth where a GHP would be used is relatively constant and as such, GHPs are not limited to areas where conventional geothermal energy generation would be used. This means that unlike solar, wind, and hydro - the suitability of which changes by location - GHPs might be used everywhere with similar cost and efficiency.

151
Q

Which of the following is not a potential source of biogas?

A

used motor oil

152
Q

Which of the following is the best location for a ground source heat pump?

A

a site with equal heating and cooling needs

153
Q

Which of the following is the most common sources of hydrogen for use in fuel cells?

A

natural gas

154
Q

Which of the following types of geothermal energy plant has the least issues with air emissions?

A

binary cycle

155
Q

Which of the following would be considered an advantage of geothermal energy? Select all that apply.

A

low cost of fuel

156
Q

Which of the following would be the approximate length of a horizontal closed loop for a 4-ton geothermal heat pump?

A

2,000 feet

157
Q

Which one of the following is not found in a geothermal heat pump system?

A

outdoor unit

158
Q

What is the COP of a heat pump with a 34,000 BTU/hour capacity and 2kW input power? Round your answer to the nearest whole number.

A

5

Coefficiency Of Performance (COP) = hh / hw
where hh = heat produced (BTU/hour)
where hw = equivalent electric energy input (BTU/hour) = 3413 * Pw
where Pw = electrical input energy in kW
COP = 34,000 / (3413 * 2) = 4.98

159
Q

From what source is the majority of the United States’ ethanol made?

A

corn

160
Q

Name one of the two main types of biofuel.

A

ethanol

161
Q

Biomass is the largest renewable energy source in the United States.

A

True

162
Q

Compared with Iowa, North Carolina has a more varied mix of biomass resources.

A

True

163
Q

Fuel cells are one of the most scalable renewable energy technologies.

A

True

164
Q

Hydrogen has no smell, but odorants are added to help detect leaks.

A

False

No odorant is light enough to travel with hydrogen.

165
Q

Hydrogen is the most powerful power source on Earth.

A

False

166
Q

In general, the temperature of rocks within the earth increases with depth.

A

True

167
Q

More than half of the United States’ corn crop is used to make ethanol.

A

False

168
Q

Most small fuel cell units utilize hydrogen storage technology.

A

False

169
Q

Refined biogas and natural gas can be used interchangably.

A

True

170
Q

The EROI of cellulosic ethanol is higher than corn ethanol.

A

True

171
Q

A clear solar window means that an array remains unshaded between which hours?

A

9:00 AM through 3:00 PM

172
Q

A PV module that is 10% shaded will most likely see what drop in performance?

A

90%

173
Q

A PV mounting system that adjusts every day for altitude but not azimuth is called a:

A

single-axis tracker

174
Q

In the northern hemisphere the days are longer in the summer and shorter in the winter primarily because of:

A

the tilt of the Earth

175
Q

Perpendicular to the sun is called:

A

normal

176
Q

The most important factor governing how much insolation falls in a particular location is:

A

latitude

177
Q

The sun will always be highest in the sky at:

A

solar noon

178
Q

To maximize the amount of insolation on a surface the angle of incidence between the surface and the sun should be:

A

90º

179
Q

Which of the following are the primary problems with tracking systems? Select all that apply.

A

cost, maintenance

180
Q

Which of the following factors will likely be your lowest concern in the installation of a residential rooftop PV array?

A

vandalism

181
Q

Which of the following statements is most accurate regarding world manufacturing of PV panels?

A

China’s share of PV manufacturing has gone from almost none to almost the majority.

182
Q

Which of the following will not be able to be determined using Google Earth when performing a preliminary solar assessment?

A

whether the site has a clear solar window

183
Q

Using the information below, determine how much insolation, in kWh/m2/day, this array would receive in March at a fixed latitude tilt? Provide only the number and round to one decimal place..

A

5.2

97% x 5.4 = 5.238 kWh/m2/day

The correct answer is: 5.238

184
Q

It is necessary to determine the electrical load and design month for a grid-tied PV system.

A

False

185
Q

The Solar Pathfinder only shows the obstructions that occur during the solar window.

A

False

186
Q

After 20 years the efficiency of a PV module drops off due primarily to:

A

weathering

187
Q

Before it can induce the photovoltaic effect, pure silicon must be:

A

doped with impurities

188
Q

What is the power output at VOC?

A

zero

189
Q

What is the efficiency of a PV module that produces 200W and is 1m x 1.5m in size? Provide only the number and round to two decimal places if necessary.

A

13.33

1.5 square meters x 1000 W/m2 = 1500W max irradiance
200 ÷ 1500 = 13.3%

190
Q

What is the rated power output (in watts) of a module with VMP of 17.1V and IMP of 2.5A? Provide only the number!

A

42.75

191
Q

What should the actual tilt be, in degrees, for a stand-alone PV array located in Nome, Alaska where the critical loads are in the winter? Provide only the number and round to one decimal place.

A

79.5

The coordinates for Nome, Alaska are 64.5039°N, 165.3994°W (this is easy to find, Google will tell you this). Therefore:

64.5° latitude + 15° tilt (critical loads are in the winter!) = 79.5° actual tilt

192
Q

This is a Sharp PV module rated at 240W. Approximately how much annual energy, in kWh, would a grid-tied fixed array containing 8 of these modules produce in area with an insolation value of 5.2? Provide only the number and round to the nearest whole number.

A

2733

240W panel rating (STC) x .75 de-rating factor = 180W AC
8 modules x 180W = 1,440W for the array
1,440W x 5.2 insolation = 7,488 Wh/day
7,488Wh/day x 365 days per year = 2,733,120 Wh/year
2,733,120 Wh = 2,733 kWh/year

193
Q

Assuming an average of 2W, what is the approximate wattage of this PV module? Provide only the number. (32 cells)

A

32

Since wattage ranges from 1-3 per module, accepted answers include:
1 x 32 = 32
2 x 32 = 64
3 x 32 = 96

194
Q

ISC is always higher than IMP.

A

True

195
Q

A 100 AH battery provides:

A

2A for 50 hours

196
Q

Advantages of microinverters include which of the following? Select all that apply.

A

smaller wiring, higher efficiency, allows for individual module tracking

197
Q

DC to AC efficiency is typically around:

A

90%

198
Q

How many AH per day is required in a 1200Ah battery bank for a DOD of 50%?

A

2,400

1200Ah per day / 0.5 = 2400Ah per day

199
Q

How many AH would a 400Ah battery bank need for 5 days of autonomy?

A

2,000

400 Ah/day * 5 days = 2,000Ah

200
Q

How many days of autonomy should be allocated for non-essential uses or for systems with a backup generator?

A

2-3

201
Q

Which of the following are characteristics of a battery? Select all that apply.

A

direct current, contain both an anode and a cathode, maintain a voltage, even when “dead”

202
Q

Which of the following functions do PV system batteries provide? Select all that apply.

A

stores excess electricity produced, provides electricity at night, establishes a consistent voltage across the system, powers larger loads than the PV array by itself

203
Q

How many amp-hours (Ah) per day is needed in a battery bank to meet the needs of a system requiring 7,092 Wh/day at 18V? Please provide only the number.

A

394

Watts = Amps x Volts
Amp-hours (Ah) x Voltage = Watt-hours (Wh)
Ah/day = (Wh per day / system voltage)
7092Wh per day / 18 volts = 394Ah

204
Q

What is the total energy load, in kWh, for the following? Please provide only the number.

120W of lighting for 8 hours per day
2000W stove for 30 minutes per day
200W TV for 4 hours per day
70W laptop for 2 hours per day

A

2.9

960 + 1000 + 800 + 140 = 2900 watt-hour/day = 2.9 kWh

205
Q

A battery that is frequently and quickly discharged will have less capacity.

A

True

206
Q

It is good practice to oversize a PV battery bank relative to the array.

A

False

An oversized battery bank will remain in a state of partial charge and will not be fully recharged, especially during cloudy weather. This will shorten life and capacity. An undersized bank will be charged up too fast, shortening battery life.

207
Q

Regardless of type and rating, new batteries should never be added to an existing battery bank.

A

True

New batteries must be added in parallel to maintain system voltage. Excessive “paralleling” increases the chance of failure from a bad cell. Even though the rating might be the same, the new batteries will have a different capacity than the old, requiring different charge rates. The internal cell resistances will be different.

208
Q

When designing a system utilizing batteries, a DOD of 50% is typically used.

A

True

209
Q

A DC-to-AC de-rating factor of which percentage is commonly used?

A

75%

210
Q

A solar thermal storage tank must be sized to meet what?

A

summer output of collector

When sizing a solar thermal system, you need start by choosing tanks that can handle what the collectors are actually producing. See slide 20 of the Site Assessment Solar Thermal PP.

210
Q

A solar thermal system designed to provide space heating should use which type of collector?

A

evacuated tube

210
Q

About how much more output will a single-axis tracker give a PV system over a fixed tilt?

A

20%

211
Q

All of the following are viable methods of dumping heat in a glycol system except:

A

draining the glycol back to a tank

During the lecture, it was noted that water is almost always used as the heat transfer fluid in drainback systems; especially when using glycol, evacuated tubes are almost always used. See slide 14 of the Components and Operation Solar Thermal PP.

212
Q

An expansion tank is found only on which type of solar thermal system?

A

glycol

213
Q

An inverter is always required on which of the following PV systems?

A

grid-tied

214
Q

Direction conversion of photons to electricity is known as:

A

photovoltaic effect

215
Q

Fixed-tilt PV systems that are grid-tied or designed for year-round loads should have a tilt equal to:

A

latitude

216
Q

How does the heat transfer fluid flow through an evacuated tube collector?

A

It flows across the top header of the collector., It does not flow to the collector at all.

217
Q

How many 24V/200Ah batteries will be required for a 24V system with 3240 Wh/day loads and 2 days of autonomy?

A

3

3240 Wh per day / 0.9 efficiency from DC to AC = 3600 Wh actually needed
3600 Wh / 24 volts = 150 Ah per day needed
150 Ah per day * 2 days of autonomy = 300 Ah per day
300 Ah per day / 0.5 DOD limit = 600 Ah per day total needed
24 volt system / 24 volts per battery = 1 battery in series
600 Ah per day needed / 200 Ah per battery = 3 battery in parallel
1 battery in series * 3 batteries in parallel = 3 batteries total

218
Q

How many days of autonomy should be allocated for critical loads or no backup?

A

5-7

219
Q

How many of the batteries in the image below will be needed in a bank designed for 1200Ah per day at 24V?

A

To get the number of batteries required in the series: 24 volts required / 12 volts per battery = 2 batteries per series
To get the number of batteries required in parallel: 1200 Ah per day / 50 AH = 24 batteries
2 batteries in series * 24 batteries in parallel = 48 batteries total

220
Q

How many volts does the average PV cell produce?

A

0.5 volts

221
Q

How much irradiance would a PV module with 25% efficiency capture?

A

250 W/m2

222
Q

If a flat plate collector is sloped to one side, what type of system is it?

A

drainback

223
Q

Relative to due south, what is the loss of performance, in percent, of a solar thermal hot water system that faces southeast?

A

3%

Relative to due south, southeast or southwest orientation will only reduce the energy produced by 3%. SE is preferred to SW because it is sunnier. See slide 14 of the Solar Thermal 2 PP.

224
Q

The controller constantly manages what?

A

the temperature of the water in the tank relative to the temperature of the collector

225
Q

What are the primary advantages of a net metered PV system? Select all that are correct.

A

PV power is credited at the retail rate., Backup power is provided during nights and inclement weather.

226
Q

What are the primary advantages of a variable speed pump over a constant speed pump? Select all that apply.

A

It does not short cycle., It is more efficient.

227
Q

What does a parabolic dish receiver have that a parabolic trough system does not?

A

external heat engine

228
Q

What is the cost of power produced, in dollars per watt, of a panel with a peak DC wattage of 400W that cost $2,400?

A

$6 per watt, $8 per watt

400W (STC) * 0.75 de-rating factor = 300W AC
$2400 / 300W = $8 per watt

229
Q

What is the maximum theoretical capacity factor of a concentrating solar power system without storage?

A

50%

230
Q

What is the primary advantage of a thermosyphon system over a batch system?

A

insulation is added to the tank

231
Q

What working fluid is most commonly used in a drainback solar thermal system?

A

water

Glycol CAN be used, but it was made very clear at ~14:35 of the second Solar Thermal lecture (slide 22 of the PP), that water is by far the most common.

232
Q

When does glycol turn acidic and corrosive in a solar thermal system?

A

when it overheats

233
Q

When does the control open the diverting valve in a solar pool heater?

A

when the collector is sufficiently warmer than the pool

234
Q

Which day of the year should be used to determine the worst-case scenario for a shading analysis?

A

December 21

235
Q

Which of the following components would not normally be purchased in the installation of a solar pool heater?

A

new pump

236
Q

Which of the following contributes to increased voltage drop? Select all that apply.

A

longer wires, smaller wires, higher ambient temperature

237
Q

Which of the following houses is likely the best candidate for solar thermal hot water in terms of economics?

A

6-person family home with an aging electric water heater

238
Q

Which of the following is an advantage of a stand-alone AC system over a stand-alone DC system?

A

Standard household loads and appliances can be accommodated.

239
Q

Which of the following is an advantage of flooded lead acid batteries (wet cells)?

A

can supply high surge current

240
Q

Which of the following is true regarding how quickly a PV panel will “use up” its stored electrons?

A

PV panels do not store any electrons.

PV panels are a perpetual converter, rather than a battery, so they do not have any electrons to “use up”.

241
Q

Which of the following would be a load powered by a Day Use PV System?

A

DC pump

242
Q

Which of the following would be considered a hybrid system?

A

PV + wind turbine

243
Q

Why are open loop solar thermal systems discouraged in most cases? Select all that apply.

A

possibility of corrosion and scale, possibility of water contamination, inadequate freeze protection

244
Q

Why can’t a solar thermal passive batch system be used in North Carolina?

A

it contains no freeze protection

245
Q

Why do solar pool heaters use unglazed plastic collectors?

A

because only low heat is needed

246
Q

How many Ah per day is needed in a battery bank to meet the needs of a system requiring 9,576 Wh/day at 12V? Do not factor in DOD or Days of Autonomy. Provide only the number and round to the nearest whole number if necessary.

A

887

Watts = Amps x Volts
Amp-hours (Ah) x Voltage = Watt-hours (Wh)
Ah/day = (Wh per day / system voltage)
9576Wh per day / 0.9 efficiency from DC to AC = 10,640Wh actually needed
10640Wh per day / 12 volts = 886.67Ah

247
Q

How many AH per day is required in a 400Ah battery bank for a DOD of 50%? Please provide only the number.

A

800

400Ah per day / 0.5 = 800Ah per day

248
Q

How many AH would a 300Ah battery bank need for 3 days of autonomy? Please provide only the number.

A

900

300 Ah/day * 3 days = 900Ah

249
Q

Use the information below to determine how much energy, in kWh/m2, a fixed latitude-tilt PV system can capture in July in Wilmington, NC. Provide only the number.

A

5.5

Under the “Fixed array” category, go to the “Latitude” line and find the “Jul” column.

250
Q

Using the module in the image below, what is the maximum amount of power (as a whole number) the module can produce? Provide only the number.

A

185

Pmp = Vmp * Imp
37.5V * 4.95A = 185W

251
Q

A parabolic trough system operates as a closed loop.

A

True

252
Q

A solar pool heater can be used to cool a pool as well as heat it.

A

True

253
Q

An AC pump can be run directly from a PV panel.

A

False

254
Q

As heat builds up due to temperature increase, the voltage in a PV module decreases.

A

True

255
Q

Concentrating solar thermal is economically viable throughout the majority of the U.S.

A

False

256
Q

Current increases at lower temperatures, but battery life decreases.

A

False

257
Q

Frequently shallow-cycling a battery will result in a longer life and higher reserve capacity.

A

True

See slide 26 of the Batteries PP.

258
Q

Overcharging shortens the life of the battery while overdischarging causes a potentially unsafe loss of electrolyte.

A

False

259
Q

Polycrystalline cells handle higher temperatures better than monocrystalline cells.

A

True

260
Q

PV panels do not usually work on cloudy days.

A

False

261
Q
A

Renewable energy (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions