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