Katharina Richert Carl Stevenson History Coal used since bronze age (2000 BC) Wood more convenient...
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Transcript of Katharina Richert Carl Stevenson History Coal used since bronze age (2000 BC) Wood more convenient...
Katharina Richert
Carl Stevenson
History
Coal used since bronze age (2000 BC) Wood more convenient until the
Industrial Revolution 1769: James Watt invents steam engine
Wood was possible, but coal became more convenient and easier to transport
Practice Problem #1
A steam engine with a power of 6000 hp is travelling for 5 hours at full speed. How much more coal than wood is needed.Energy density of wood: 17 MJ kg-1
Energy density of coal: 34 MJ kg-1
1 hp = 0.75 kW
Therefore, the power of the engine is 4500kW (0.75 x 6000)
The engine will use 4500 kJ Energy used in 5 hours = 5 x 60 x 60 x
4500 x 1000 = 81 x 109J 81 x 109/ 17 x 106 = 4765 kg of wood About half the mass of coal is needed
Oil (Petroleum) Thick, sticky substance More difficult to utilize than coal for a long
time 1852: Ignacy Lukasiewicz invented a
method of refining crude oil to kerosene It has a higher energy density than coal
and is easier to transport Liquid nature has led to many
environmental disasters Energy density of kerosene: 43.1 MJ kg-1
Generation of Electricity Before use of electricity, coal was used for
heat and kerosene was used for lightingTransport was very costly
1831: Michael Faraday’s discovery electromagnetic effects
1866: Werner Siemens: invented the dynamo (converts mechanical energy to electrical energy on a big scale)
1884: Sir Charles Pearson: invented the steam turbine
Picture of a typical coal-fired power plant
The heat from the furnace boils water in the boiler that turns into steam and powers the turbine, which turns the generator and produces electricity. When the steam comes out of the turbine it is cooled, condenses and this water is returned to the boiler
Sankey Diagram of Coal Plant
ChemicalEnergy
Hot Steam
MotionElectricity
Friction
Waste HeatExhaust
Gas
Gas-Fired Power Station More efficient than
coal because there can be two stages of energies
Burning gases blasted through a turbine
Heat produced can be used to boil water; same as coal-fired power station
Sankey Diagram of Gas-Fired Power Station
The wasted heat can also be used to heat houses. This improves the efficiency to 55%
Practice Problem #2
A steam engine with a power of 8000 hp is travelling for 3 hours at full speed. How much more coal than wood is needed?
Energy, Power, and Energy, Power, and Climate Change: Nuclear Climate Change: Nuclear PowerPower
By:By:Richard FrischeRichard Frische
Ana RodelasAna RodelasLonnie EarlsLonnie Earls
Creating Nuclear FuelCreating Nuclear Fuel
Chain reactionChain reaction
• Binding energy of 235U will increase, but it can’t hold this energy so it releases it
• Uranium must also be a certain mass
This energy is used to generate electricity
Neutrons must be going a certain speed to maintain the chain reaction (controlled by moderators)
Nuclear FusionNuclear Fusion
- the difference in mass is converted to energy
Fussion: Nuclear Fussion: Nuclear ReactorsReactors
more energy going out than in
plasma as fuel
Fuses together nucleii at temperature of 100 million K
Fusion: Magnetic Fusion: Magnetic ConfinementConfinement
Plasma is made to travel inside the donut shaped ring-Tokomak
particles are given energy so they move faster and faster
Energy to heat up the plasma comes in burst-huge energy supply needed to fuse
Fusion: Hydrogen BombFusion: Hydrogen Bomb
Gives heat and compresses nucleiiGives heat and compresses nucleii Lots of energy but uncontrollable Lots of energy but uncontrollable
AdvantagesAdvantages
AdvantagesAdvantages
-Extremely high energy density-Extremely high energy density
-Large reserves of uranium-Large reserves of uranium
DisadvantagesDisadvantages
DisadvantagesDisadvantages
-Nuclear Waste-Nuclear Waste
-Meltdown-Meltdown
-Nonrenewable-Nonrenewable
Japanese Power Plant after 2010
Three Mile Island before Nuclear Meltdown
Problem 1Problem 1
Number 5 on the end of topic 8Number 5 on the end of topic 8
Problem 2Problem 2 A sample of radioactive material contains the A sample of radioactive material contains the
element Ra 226. The half-life of Ra 226 can be element Ra 226. The half-life of Ra 226 can be defined as the time it takes fordefined as the time it takes forAA the mass of the sample to fall to ½ its the mass of the sample to fall to ½ its
original valueoriginal valueBB ½ the # of atoms of Ra 226 in the ½ the # of atoms of Ra 226 in the sample to sample to decaydecayCC ½ the # of atoms in the sample to ½ the # of atoms in the sample to decay decay DD the volume of the sample to fall to ½ its the volume of the sample to fall to ½ its
original valueoriginal value
Problem 2Problem 2 A sample of radioactive material contains the A sample of radioactive material contains the
element Ra 226. The half-life of Ra 226 can be element Ra 226. The half-life of Ra 226 can be defined as the time it takes fordefined as the time it takes forAA the mass of the sample to fall to ½ its the mass of the sample to fall to ½ its
original valueoriginal valueBB ½ the # of atoms of Ra 226 in the ½ the # of atoms of Ra 226 in the sample to sample to decaydecayCC ½ the # of atoms in the sample to ½ the # of atoms in the sample to decay decay DD the volume of the sample to fall to ½ its the volume of the sample to fall to ½ its
original valueoriginal value
Problem 3Problem 3
A piece of radioactive material now has about A piece of radioactive material now has about 1/16 of its previous activity. If the half-life is 4 1/16 of its previous activity. If the half-life is 4 hours the difference in time between hours the difference in time between measurements is approximatelymeasurements is approximately
AA 8 hours8 hours
BB 16 hours16 hours
C C 32 hours32 hours
DD 60 hours60 hours
Problem 3Problem 3
A piece of radioactive material now has about A piece of radioactive material now has about 1/16 of its previous activity. If the half-life is 4 1/16 of its previous activity. If the half-life is 4 hours the difference in time between hours the difference in time between measurements is approximatelymeasurements is approximately
AA 8 hours8 hours
BB 16 hours16 hours
C C 32 hours32 hours
DD 60 hours60 hours
Solar Power
By:
Carlos Duarte &
Chris Ludlow
Energy from the Sun Electromagnetic
radiation from the sun3.90 x 1026 J
Earth’s orbital radius1.5 x 1011
Solar Constant
2211
26
1380)105.1(4
1090.3
m
W
Energy from the Sun Cont’d Different parts of the Earth’s surface receive
different amounts of solar radiation. The amount recieved will also vary based on the
seasons
The Solar Heating Panel Designed to capture
as much thermal energy as possible.
Hot water used domestically, saves electricity
Photovoltaic Cell (Solar Cell) Photons from sun are
absorbed by semiconductor which emits electrons.
Electric field due to semiconductors causes electrons to flow in an external circuit
Voltage in single cell = small so they use many cells.
Advantages “Free” Renewable Clean
Disadvantages Only works during the day Affected by cloudy weather Low power output Requires large areas High initial costs
m
v
f v
PE mgh
PE mgh
PE mgA
h A
m v (AL2
)
PE (AL)gA
2
A2Lg2
Power PE
T
A2Lg2
v
f v
A2Lgv
2
1
2A2gv(L)
PE A2Lg
2
power per unit lenght = 1
2A2gv
A - amplitude (m)
- density (kg m-3)
g - gravity (Nkg-1)
v - velocity (ms-2)
•Renewable
•Independent
•Low safety risk
•“Clean”
•Experimental
•Coastline in high demand
•Inconsistent
•Low power output
16. Waves of amplitude 1m roll onto a beach at a rate of one every 12s. If the wavelength of the waves is 120 m, calculate:
a) the velocity of the wavesb) how much power there is per metre along the shorec) the power along a 2km length of beach
16. A tsunami wave of amplitude of 20 m slams into the Japanese coast of Omoe peninsula with a velocity of 23 ms-1. Calculate:
a)how much power there is per metre along the shoreb)the power along a 1km length of beach
Wind Power
By: Madeleine & Kyle
Energy Transformations
Solar energy KE of wind
KE of turbineElectric energy
heatingEarth
Mathematics
Area ‘swept out’ by blades = A = πr2
Volume of air passing through turbine in one second = v A Mass of air passing through turbine in one second = v A ρ Kinetic energy m available per second
Density of air ρ
Wind speed v
r
Not 100% efficient
Advantages
Very ‘clean’ production Renewable source of
energy Source of energy is free
Disadvantages
Source of energy unreliable Low energy density Some consider large wind
generators to ‘spoil’ countryside Can be noisy Best positions for wind
generation are far from centers of population
Example problem
A turbine with a turbine blade length of 54 m is operated in a wind speed of 10 m s-1
. The density of air is 1.2 kg m-3
.(a) How much power is in the wind passing
through the turbine?(b) How much electrical power can be generated
if the turbine is 20% efficient?(c) If the wind speed increased to 15 m s-1 , how
much power would be produced?
Example problem #2 It is required to design wind turbines for a wind
farm for which the following information is available.Total required annual electrical energy output: 120
TJMaximum number of turbines: 20Average annual wind speed at site: 9.0 m s-1
Deduce the average power output required from one turbine is .19 MW.
Estimate the blade radius of the wind turbine that will give a power output of .19MW
(Density of air = 1.2 kg m-3 )
Geothermal Energy
Ryan Avelar&
Mykella Jones
How it works Hot water near volcano, geyser or
thermal source Hot water piped to the surface by
drilling to extract steam and produce electricity.
Old Faithful Energy??
Advantages
Affordable and sustainable solution to fossil fuels (saves 80% of costs)
Decrease emissions Direct Use Philippines, Iceland, and El Salvador
- produce 25+% of electricity
Disadvantages
Not Widespread Source of Energy High Installation Costs (investment) Can Run Out Of Steam May Release Harmful Gases