1. Fossil Fuels

2. What is a Fossil Fuel?
Burn to change chemical structure and release energy
Coal
plants hardened by sand and mud (photosynthesis energy)
Must be dug up (expensive and difficult)
rate used greater than rate of production (non renewable)

3. What is a Fossil Fuel? Oil and Gas
microscopic organisms hardened over time
easier to extract (liquid form)
non renewable

4. Geography Easy to find (as of 4000 years ago)
Must use coal near source (hard to transport)
eg: trains must carry coal
OIl is easily pumped - can be transported (pipes)
Drill technology allows drilling across world

5. History Originally wood used - more suited to needs
Coal accessible 1769 (Industrial Revolution)
Coal has twice the energy density of wood
Crude oil refined to kerosine (1852)
oil has higher energy density than coal
As of years of coal left (1E15kg)
As of about 1E14 liters of crude oil left

6. Transportation and Storage
Coal
Required a lot of time and energy to transport
Combustion risks
More efficient to produce electricity
Oil and Natural Gas
Can be pumped through pipes
Transportation Environmental problems
Stored indefinitely

7. Energy Density
Energy Density( of Fuels) : The ratio of the energy released from the fuel to the mass of the fuel consumed
The amount of energy that can be extracted per kg of fuel.
Fuels with high energy density are easier to transport than those with lower densities.

8. Energy Density Chart

9. Power Stations
A Power Station: An industrial place for the generation of electric power.
Has a generator, a rotating machine that converts mechanical power into electrical power by creating relative motion between a magnetic field and a conductor.
The energy source harnessed to turn the generator varies widely.
It depends chiefly on which fuels are easily available, cheap enough and on the types of technology that the power company has access to.

10. Coal-fired Power Stations
Coal Steam
Steam Electricity
Steam Water

11. Coal-fired Power Stations
Sources of waste heat:
exhaust gas
turbine condensing
friction
40% Efficiency

12. Oil-fired Power Stations
Same set-up as Coal-fired Power Stations
Oil is burnt to produce energy needed to boil the water
Cleaner, easier to get out of the ground, and easier to transport than coal
Efficiency is about 59%

13. Gas-fired Power Station
More Efficient than coal
Two stages of energy use
Burning gas goes through a turbine => heat produced is used to boil water => steam powers a steam turbine

14. Gas-fired Power Stations
Up to 59% efficient
If wasted heat goes to homes => 80% efficient

15. Environmental Repercussions
Coal-fired and Gas-fired Power Stations= harmful pollution from exhaust
Oil refinement=efficiency… but also= oil spills
Serious consequences (i.e. BP Oil Spill)
Power Station developments focus on recovering exhaust (by different trapping techniques) back into the ground for reuse

16. Practice Problem #1
When a car is driving at 80 km/h it is doing work against air resistance at a rate of 40kW
a) How much work does the car do against air resistance in 1 hour?
40E3(J/s) * 60 * 60 = 1.44 E8 J
b) If the engine is 75% efficient, how much energy must the car get from fuel?

17. Problem 1 (cont)
1.44E8 J/.75 = 1.92E8 J
c) If the energy density of the fuel is MJ/kg, how many kg of diesel will the car use?
1.92E8 J/45.8E6 J/kg = 4.2kg

18. Practice Problem #2
A coal-fired power station gives out 1000 MW of power
a) How many joules will be produced in one day?
1000E6 J * 60 * 60 * 24 = 8.64E13
b) If the efficiency is 40%, how much energy goes in?

19. Problem 2 (cont)
8.64E13 J/ .4 = 2.16E14 J
c) The energy density of coal is 32.5 MJ/kg. How many kg are used?
2.16E14 J/32.5E6 J/kg = 6.65E6kg
d) How many rail trucks containing 100 tons each are delivered per day?
1 ton = 1000 kg

20. Problem 2 (cont)
6.65E6/(1000*100) = 66.5
67 rail trucks

21. Austyn Howard Ciara Jasinski Dillon Labban Tyler Ritter
Nuclear Power
Austyn Howard
Ciara Jasinski
Dillon Labban
Tyler Ritter

22. The Fission Reaction Big nucleus splits into two smaller nuclei
Loss of mass and energy, E=mc2
i.e. 236U → 92Kr + 142Ba + 2n
Some neutrons are lost, so mass is lost
The total number of protons remains the same

23. The Chain Reaction Splitting a nucleus requires energy
Can be gained by adding a neutron
Adding a neutron increases the binding energy of the nucleus
Nucleus can’t get rid of this energy and splits in two
Results in too many neutrons, so some are released
Released neutrons are captured by other nuclei, resulting in more nuclei splitting and a chain reaction

24. Moderation of Neutrons
Chain reaction only occurs if neutrons are moving slowly
Otherwise they pass through the nucleus
KE should be about 1 eV
Neutrons must be slowed down
Moderator nuclei are placed between nuclei where fission must occur in order to slow them down

26. Critical Mass
Definition: the minimum mass required for a chain reaction
Size of the reacting element, i.e. uranium, matters
If it’s too small, the neutrons will pass the uranium before they slow down enough

27. Nuclear Fuel
Natural Uranium is mostly made up of 238-U (99.3%) and 235-U (0.7%). Before it can be used as nuclear fuel it needs to go through fuel enrichment.
in nuclear reactors the fuel is stored inside small cylinders that are stacked together to make rods
Depleted uranium is used to penetrate armored vehicles, is 40% less radioactive than typical uranium
When U-235 is used up it makes
Pu-239 that goes through fission
and can then be used for energy
production or bombs

28. Controlling the rate of reaction The loss of control: The atom bomb
If more than one neutron from each fission goes on to make another fission then the reaction will accelerate; if less than one then it will slow down
In order to keep the bomb from exploding before hitting the ground the uranium and moderator are kept separate from each other
Weapon grade amount of Uranium and isotope:
85% 235-U is considered ‘weapon grade’ (about the same amount as a soft drink can would work)
20% isotope is possible to make a bomb
The only way to slow down the reaction is to introduce neutron absorbing rods (such as Boron) in between the fuel rods

29. The Nuclear Power Station
nuclear reactor
It’s mechanism is similar to that of a furnace in a steam generator

30. The Nuclear Power Station
nuclear reactor:
an apparatus or structure in which fissile material can be made to undergo a controlled, self-sustaining nuclear reaction with the consequent release of energy (heat).
3 crucial components:
fuel elements
moderator
cooling rods

31. The Nuclear Power Station
fuel elements
heavy fissile elements
235U or 238U
when these fuels are struck by neutrons, they are in turn capable of emitting neutrons when they break apart.
chain reaction

32. The Nuclear Power Station
Moderator
slows down neutrons
heavy water (deuterium)

33. The Nuclear Power Station
control rods
control the rate of fission reactions
absorb neutrons
Boron or Cadmium

34. Problems with Nuclear Energy
getting the uranium
you can mine it, but…
open-cast mining hurts the environment
underground mining can hurt the workers
you can use “leaching,” but…
this can lead to contamination of groundwater

35. an open pit uranium mine in Namibia

36. Problems with Nuclear Energy
Steps to Achieve a Meltdown
1. do a bad job of controlling a nuclear reaction
2. allow fuel rods to melt
3. let the pressure vessel burst
4. release radioactive material into the atmosphere

37. Problems with Nuclear Energy
meltdowns can be caused by:
a malfunction in the cooling system
a leak in the pressure vessel
the reactor would be severely damaged, but external damage is limited by the containment building
protects the outside from dangerous material, protects the inside from missiles
Tyler

38. revisiting the diagram, but examining different components

39. Waste
low level waste
traces of radioactive material that need to be carefully disposed of
kept away from humans for years
old reactors
left alone for many years before demolition
encased in concrete

40. Waste high level waste (spent fuel rods)
plutonium isn’t safe for at least 240,000 years
suggestions:
send it to the Sun
put it at the bottom of the ocean
bury it in the icecaps
drop it into a very deep hole
current plan: store it underwater at the site of the reactor for several years, then seal in steel cylinders

41. Waste weaponizing fuel not enough 235U to be used
process that enriches uranium into fuel, could be used to make it weapons grade
plutonium is most commonly used, can get it by reprocessing spent fuel rods

42. Benefits of Fission Doesn’t produce CO2 or other greenhouse gases
Fission results in increased sustainability
Plutonium can be created through the fission process, resulting in 2000 years of fuel
Naturally found uranium is estimated to only last 100 years

43. Fusion was thought of as the answer to energy problems in the 1950s
the total mass of the larger nuclei is less than that of the smaller two combined, the extra mass is turned into energy
fusion reactors have come close to creating more energy than what was put in but is still not enough to commercially produce energy
Plasma (a gas in which nuclei and electrons are separate) is used to create energy in the system
magnetic fields are used to move the
particles through the system

44. Burning Plasma and Fusion Bombs
the problem with creating fusion through energy is that every time more plasma is added the temperature has to be significantly increased in order for the nuclei to fuse
the fusion bomb (hydrogen bomb) gives out a huge amount of energy but is not controllable

45. The Sun
gravity pulls all of the mass inward → creates super duper high pressure (100,000,000,000 atm)
hydrogen atoms fuse together → nuclear fusion
15 million degrees Fahrenheit at the core

46. The Sun

47. Catrina Letterman Joseph Leung Cyam Cajegas
Wave Power
Catrina Letterman
Joseph Leung
Cyam Cajegas

48. Origin of waves The movement of air disturbs the water, causing waves
As waves spread out, they spread their energy, which can be used to turn turbines

49. Oscillating Water Column (OWC) Ocean-Wave Energy Converter
Device built on land that uses the kinetic energy of waves to force [compress] air in and out of a turbine which generates electrical energy

51. Generating Electricity from Waves

53. Advantages/Disadvantages
No Greenhouse Gas Emissions
Renewable Form of Energy
Enormous Energy Potential (30 to 100 kW per meter)
Reliable (Most in the winter season)
Area Efficient (half square mile -> 30MW)
Offshore Wave Power D
1. Environmental Effects (sea life and tourism)
2. Expensive
3. Regular Maintenance
4. Still Developing

54. Calculating Energy in a wave

55. Calculating Power in a wave

56. Practice Problems
Waves of amplitude of 1 metre roll onto a beach at a rate of one every 12 seconds. If the wavelength of the waves is 120 metres, calculate:
a. the velocity of the waves
b. how much power there is per metre along the shore
c. the power along a 2km length of beach

57. a. v = m/s
120 meters/12 seconds = 10 m/s
b. Given that power = pvgA^2/2,
(1kg/m^3 * 10 m/s * 9.8 m/s^2 * 1^2 m^2) 2
= 49 kW
c. 49 kW * 2000 m = 98 MW

58. Tidal Power

59. Origin of tides Tides due to gravitational change of moon
Movement of tides can be used to drive turbines

61. Turbines are turned as tide comes in and goes out

62. Advantages/Disadvantages
No Greenhouse Gas Emissions
Renewable Form of Energy
Predict Tides
Maintenance Cheap
Long Lifespan
High Energy Density D
1. Environmental Effects (sea life and tourism)
2. Expensive
3. Few Viable Locations
4. Still Developing
5. Unpredictable Tidal Energy
6. Short Duration of Power Generation
7. Energy Transmission expensive and difficult

63. TEST TEST TEST TEST TEST TEST

64. 1. From what energy source are waves directly derived from? a. The Sun
b. Wind
c. Geothermal
d.The Moon

65. 2. What is NOT required to determine the power of a wave? a. Density
b. Wavelength
c. Amplitude
d. Temperature of water

66. 3. The tides are mainly caused by… a. The Sun b. The earth’s rotation
c. The Moon
d. The wind

67. 4. How much power (approximately) can a pelamis generate
a. 150 horsepower
b. 150 kJ/s
c. 750 kW
d. 750 kJ

68. 5. An oscillating water column generates power by… a. Air compression
b. Tidal Change
c. Wave’s Momentum
d. Magnetic A/C Generator Buoy

69. Free Response Question
Waves off the 1.5km Leung Coast are used to generate power. A wave is modeled below

71. Free Response Question
a. Determine the wave velocity.
b. Determine the mass of 1 wave approaching the coastline. The Density of Seawater is 1027 kg/m^3
c. Calculate the potential energy of one wave.
d. Calculate the power of one wave.

72. Free Response Question
e. BONUS: What should the wave velocity be in order to power the 30000kW mega-awesome laserlight show in Joseph’s Coastal Mansion?

73. Ray Win KC Sumner Seanna Morin Jakob Hernandez
Wind Energy
Ray Win
KC Sumner
Seanna Morin
Jakob Hernandez

74. Kinetic Energy of Turbine
Wind
Solar energy
Sun heats earth, creates wind
Solar Energy
Kinetic Energy of Turbine
Kinetic Energy of Wind
Electrical Energy

75. Coastal Winds Due to different rates of heating of the land and sea
Sea has a larger specific heat capacity than the land
Example: Wind at beaches

76. Katabatic Winds
Formed when high air pressure is caused by dense cold air pressing down at the top of a mountain
Air flows downhill
Examples:
When cold air from Alps and Massif flow down towards Mediterranean coast

78. The Wind Turbine Similar to a fan or a propeller on an airplane
Air pushes the fan blades causing a generator to turn, creating electrical energy
Usually turbines grouped together in “wind farms”

79. The Wind Turbine Energy Calculations
Mass of column of air passing trubine in one second =𝜌𝑣𝜋 𝑟 2
𝐾 𝐸 = 1 2 𝑚 𝑣 2 = 1 2 𝜌𝑣𝜋 𝑟 2 𝑣 2 = 1 2 𝜌𝜋 𝑟 2 𝑣 3

80. The Wind Turbine
Formula assumes wind stops moving after it passes turbine
All kinetic energy is not transferred to the turbine
Theoretically, maximum percentage of wind’s energy that can be extracted using a turbine is 59%
Also finds power due to the calculation using mass of air that passes through in one second

81. Places for Wind Turbines
A windy place
Regular wind
Turbine doesn’t have to change orientation
Easy to lay power lines
Easy to build

82. Advantages Clean production Renewable energy source Free energy source
No harmful chemicals
Renewable energy source
Free energy source
After initial cost

83. Disadvantages Wind is unreliable Low energy density
Large area required for significant energy
Ruins country landscape
Can be noisy
Best places often far from population centers

84. Sample Problems
A community wants to build a wind farm to fit its needs.
Total required annual energy output: 100 TJ
Space for 20 wind turbines
Average annual wind speed: 9 ms-2
Deduce the average power output required for one turbine
Estimate the blade radius that will give a power output found in part a (Density of Air = 1.2kgm-3)

85. Sample Problem
Deduce the average power output required for one turbine
𝑇𝑜𝑡𝑎𝑙 𝑃𝑜𝑤𝑒𝑟 𝑖𝑛 𝑂𝑛𝑒 𝑌𝑒𝑎𝑟= 100 × ×60×24×365
There are 20 turbines
3.1× =1.6× 𝑊

86. Sample Problem
Estimate the blade radius that will give a power output found in part a (Density of Air = 1.2kgm-3)
𝑃𝑜𝑤𝑒𝑟 𝑂𝑢𝑡𝑝𝑢𝑡= 1 2 𝜌𝜋 𝑟 2 𝑣 3
1.6 × 10 5 = 1 2 (1.2)𝜋 𝑟 2 (9) 3
𝑟≈10.8 𝑚

87. By Ceres, Jace, Michael, and Terry
Solar Power
By Ceres, Jace, Michael, and Terry

88. Energy from the Sun
The sun emits 3.9E26 J per second of electromagnetic radiation
This energy spreads out by the inverse square law since the energy is distributed in a sphere

89. Inverse Square Law Intensity can be found by the formula I=P/(4πr2)
I=Intensity (power per unit area)
P= total power of point source
r= distance away from the point source

90. Solar Power intensity on earth
Power per meter squared of solar energy above the Earth’s atmosphere: (solar constant)
Earth’s orbital radius: 1.5E11 m
Intensity = 3.90E26 / (4π X 1.5E11)2= W·m-2

91. Solar Power on Earth’s Surface
Amount of solar radiation that reaches the Earth surface depends on how much atmosphere the light has to get through
Different latitudes on the Earth’s surface will receive different amounts of radiation
Will also vary with the seasons

92. Atmosphere Travel Distance
More
North
Less

93. Solar Heating Panel
Panel uses heat from sun to heat water for household use.
Sunlight goes through glass panel and is absorbed by black metal plate.
Hot metal plate then heats water for use.

94. Solar Heating Panel

95. Solar Example
A 5 m2 solar heating panel is in a place where the sun’s intensity is 800 Wm-2.
What is the power incident on the panel?
800 Wm-2 * 5 m2 = 4000 W

96. Solar Example
If it is 40% efficient, how much energy is absorbed per second?
4000 W * .4 = 1600 W
If 1 kg of water flows through the system in 1 minute, how much will its temperature increase?

97. Solar Example
If 1 kg of water flows through the system in 1 minute, how much will its temperature increase? (Specific heat capacity of water Jkg-1K-1)
q = mcT T = q/(mc)
1600 W*(60 s/1 min)/(1 kg*4200 Jkg-1C-1) = K

98. Photovoltaic Cell Converts solar radiation into electrical energy
Semiconductors release electrons when photons of lights are absorbed
Different types of semiconductors create an electric field

99. Photovoltaic Cell Only produce a small amount of p.d. and current
Using in series will get higher voltages
Using in parallel can provide higher current

100. Photovoltaic Cell

101. Photovoltaic Example
A photovoltaic cell of 1 cm2 is placed in a position where the intensity of the sun is Wm-2.
If it is 15% efficient, what is the power absorbed?
1 cm2 = .0001m2
1000 Wm-2 * m2 = .1W

102. Photovoltaic Example .1 W * .15 = .015 W
If the potential difference across the cell is 0.5 V, how much current is produced?
P = IV I = P/V
0.015 W/0.5 V = .03 A

103. Advantages vs. Disadvantages
No harmful chemical by-products
Renewable
Free energy source
Disadvantages
Only utilized during the day
Unreliable (cloudy days)
Large area needed for significant amount of energy

104. Energy, Power, and Climate Change: Hydropower
Michele Wang
Tori Barr
Diego Martinez
Jacobo Grimaldo

105. What is hydroelectric power?
The production of electricity through the conversion of gravitational potential energy from falling or flowing water.

106. Origin Originally from the sun:
Heat from the sun turns the water into vapor, which turns into clouds, which go over the land and rain over the land.
Rain water on high ground has PE, and can be converted into electricity through rivers and lakes.

107. Water Cycle

108. Gravitational PE PE=mgh
h is the difference between the outlet from the lake and the turbine.
Average height is used where the height is uneven.

109. Pumped Storage Schemes
Turn off hydroelectric power at night.
Excess power from coal-fired power stations can be used to pump water into a reservoir. (costly to turn off and back on)
Water from reservoir can drive turbines during night.
Reduces amount of fossil fuel used.

110. Pumped Storage Schemes Cont.

111. Run-of-the-river power stations
Use water diverted from a fast-flowing river without damming the river.
For areas where there would be need to dam river valley to create a difference in height for the turbines.

112. Issues Supplying electricity can be done through wires.
Result in energy loss since wires get hot.
Factories dependent on this energy are located closer to the power stations.
Some build small-scale power stations near where people live.

113. Pros: Renewable Emission-free Dams can provide a storm surge barrier
Local environmental impact, in contrast to global
Regulate water flow

114. Cons: Construction costs Requires specific locations
Harm habitats along rivers
Non-continuous