1. Where does our electricity come from?
Electricity is made or generated in different ways.
Most of our electricity is made using fossil fuels.
coal
gas
oil

2. So What Exactly Is Electricity?
Electricity by definition is electric current that is used as a power source!
This electric current is generated in a power plant, and then sent out
over a power grid to your homes, and ultimately to your power outlets.

3. I guess the next question would be...
What is Electric Current?
The movement of charges such
as electrons is called current, and
this electrical current is what
powers household appliances.
Charge Passing
Through A Given Area
Time
Electric Current =

4. An easier way to think of electric current is to picture cars going
through a Turnpike or Parkway Toll.
The cars could represent
electrons or charge, and the
toll booth could represent the
cross sectional area of the
wire at a certain point.
If you counted the number of cars or electrons, that passed through
the toll booth or a certain cross sectional area of the wire, and divided
that number by the time it took for those cars or charges to pass,
you would get the current!

5. So How Is An Electric Current Generated?
Electric current generation - whether from fossil fuels, nuclear, renewable fuels, or other sources is usually
based on the:
Simple Equation
For
Electricity Generation

6. What does copper wire and magnets have to do with Electricity?
In September of 1831, Michael Faraday
made the discovery of Electromagnetic Induction.
Faraday attached two wires to a disc and
rotated the disc between the opposing
poles of a horseshoe magnet creating
an electric current.

7. Motion is Essential
If you place a magnet and a conductor (copper wire), in a room together
there will be no electric current generated.
This is because motion, from our equation for electricity, is missing!
An electric current is not generated unless the magnetic field is moving
relative to the copper wire, or the copper wire is moving relative to the
magnetic field.

8. Simple Electric Generator
So simple electric generators found in power plants contain, magnets
and copper wire that when put into motion relative to one another
create the electric current that is sent out to homes.
The major problem in
electricity generation
Is where does the
Motion come from
that keeps the
copper wire and
magnets moving
relative to one
another.
In this case, wind power applies a force to the blades that turns them.
The spinning blades, spin an armature that turns the copper wire
relative to the magnetic field. As long as the blades spin, electricity
will be generated!

9. Electricity Transmission
- Alternating Current of 60 Hz produced by generator
Resistance losses are smallest at high voltages and low currents

10. What Happens At Home? At home, electric current that was generated by
generators in the power
plant is used to power
electric appliances.
The electric current,
running through the
copper wire causes
the armature to spin
which is how most
motors generate
motion.

11. Why do you think these are called fossil fuels?
Millions of years ago, before the dinosaurs roamed the earth, lots of plants grew strong from the energy of the sun. Then they died and became buried in thick layers beneath lots of mud and soil. The remains of animals became buried as well. Over the millions of years, the mud and soil changed to rock and the layers above the rotting plants and animal remains grew heavier and heavier and thicker and thicker.
All these organic remains (dead plants and animals) got squashed and a mixture of pressure and heat turned some organic material into coal, some into oil and some into natural gas. People found out that if they dug down deep enough and got these fossil fuels out, they could burn them to get energy.

12. So how do we get electricity from fossil fuels?
Most electricity is produced by burning fossil fuels in power stations.
Coal, oil and natural gas are burned in furnaces to heat up water. The boiling water makes steam which pushes the gigantic blades of a turbine to produce electricity.
Power stations give off lots of steam which you can see.
Power stations give off pollution, which you can’t see.
When we burn fossil fuels we put lots of carbon dioxide into the air. This is a cause of Global Warming.

13. 2. Burn biomass, fossil fuels, or natural gas to release the stored chemical energy is used to heat water to produce steam and transform it into heat. The steam is used to turn a turbine that is connected to an electrical generator.

14. 3. Burn natural gas and use the hot gases that are released to turn a turbine that is connected to an electrical generator.

15. It takes millions of years to make fossil fuels
What will happen when they run out?
Because fossil fuels won’t last for ever we call them non – renewable. This means they can’t be renewed.
Look at a piece of coal – think how long it took it to be formed. What is it like?

16. Fossil Fuels – Oil Refinery Pasadena - Texas
Standard Large Power Plants Provide 1 Giga-watt of electric power
and releases 2 Giga-watts of thermal power as waste heat. An
efficiency averaging around 30%.
9000 tons of coal a day
40,000 barrels a day or one tanker a week of oil
-generates about 5.3 x 10^9 kwh/year
-powers a city of a million people

17. total world production in 2009 of
petroleum is 84,000,000 barrels / day
an average well in the US produces
only 11 barrels / day
In Saudi Arabia an average well
produces 9600 barrels /day
Oil Drilling Platform
Cook Inlet, Alaska

18. How do fossil fuels create motion?

19. Hydroelectric Power Conversion from potential energy of
water to electric energy is at 80 – 90%
efficiency
-Hydroelectric projects in the United
States have rated capacities from
950 – 6480 MW
The use of Water Power is much
greater in some other countries.
Norway obtains 99% of its electricity
from water power. Nepal, Brazil, and
New Zealand are close seconds.
Water generated - Hydroelectric
Shasta Dam In California

20. - Hydroelectricity has dropped from producing 30 % to 10% of US electricity
- Large fluctuations in output are mainly due to variable rainfall totals

21. Problems With Hydroelectric Power
About 50% of the United States potential for hydroelectric energy has been
tapped. However, further advances are unlikely.
The Wild and Scenic River Act and the Endangered Species Act have
inhibited development of some sites
Silt collection in hydroelectric Dam storage volumes over time causes
maintenance issues, as well as environmental concerns
The loss of free flowing streams and land due to flooding behind the dam
disturbs the life of species: eg – Salmon
- Possibility of dam failure

22. Some countries use nuclear power
Nuclear power plants use a material called uranium to produce electricity.
Nuclear power plants make electricity by splitting tiny atoms of the uranium to release energy.
Nuclear plants also have waste materials that are very dangerous and have to be looked after safely for thousands of years.
Nuclear power plant

23. 4. Split uranium atoms to release nuclear energy that is used to heat water to produce steam to turn a turbine that is connected to an electrical generator.

24. -There are 109 power reactors in the United States
-Produce 22% of nation’s electricity
- In France 79% of electricity comes from nuclear reactors
Nuclear Power
Plant electrical output 1220 MW
-Plant efficiency 34%
Diablo Canyon - California

25. The Reactor Big Picture

26. Nuclear Energy Problems and Concerns
In normal operations a nuclear reactor produces some environmental
emissions. E.g.: escape of radioactive fission products through cracks and
diffusion, radioactive H3 in small amounts in discharged water
Core meltdown is possible, but unlikely due to negative feedback and
shutdown systems
Even after shutdown there is 7% of normal power generation still in the
reactor fuel rods. This may be sufficient enough to melt core and destroy
the reactor, if cooling water is not supplied
A study entitled “Severe Accident Risks: An Assessment for Five US
Nuclear Power Plants” conducted by NRC in 1990, shows that for all the
109 reactors now operating in the United States over a 30 year lifetime
there is about a 1% chance of a large release due to internal events.

27. How else can we produce electricity?
Photo
Voltaic
panels
Wind turbines
Water wheels
These are some of the ways we can get ‘renewable’ energy. This means that the source of the energy will not run out.
How is the electricity being generated?

28. 5. Use a photovoltaic cell to convert the suns energy into electricity. 

29. 1. Use Mechanical energy, wind, or moving water to turn a turbine that is connected to an electrical generator.

30. Where does the motion needed to keep the copper wire moving relative
to the magnetic field come from?
attains between 50 – 70% efficiency
- one windmill’s average energy
output ranges from 11.4 W/m^2 –
57 W/m^2 depending on how windy
wind farms tend to generate between
50 and 600 Kw
- California currently produces ¾
of all the wind generated electricity
in the world.
Wind generated
Kilronan Wind Farm In Ireland
-North Dakota with 20 times the wind potential of California has not
erected a single wind turbine

31. Problems With Wind Power
Wind variability must be overcome by system design
- Basic energy Storage
Enviornmental Concerns
- Differences in pressure gradients around wind turbines affect birds
Noise from the turbines affects people and animals
Eyesore, the appearance of mile after mile of wind machines with
transmission lines is of concern to the public

32. Other Energy Considerations
Solar Power – uses the sun energy to either boil water or directly converts
solar energy to electrical energy
Ocean Thermal Energy Conversion – uses temperature differences
between different depths of ocean water to drive a heat engine. Working
fluid is ammonia which is gas at room temperature.
-Biomass Energy: Municipal Solid Waste – burning wastes to drive heat
engines
Geothermal Energy – based on naturally occurring heat in the Earth in the
Earth due to radioactive decay
Tidal Energy – uses the gravitational pull of the moon on our oceans to
drive turbines

33. Proportion of World’s energy consumption - 1997
Proportion of the world’s
Electricity generation

34. Renewables
Non-renewables

35. Electricity?
Electricity is all about electrons, which are the fundamental cause of electricity
Static Electricity - involves electrons that are moved from one place to another, usually by rubbing or brushing
Current Electricity - involves the flow of electrons in a conductor

36. On the Move
Electrons in the outer rings or shells of atoms are bound more loosely to the nucleus
Such electrons tend to break free from the nucleus and wander around amongst other nearby atoms
Such electrons are called free electrons

37. Current = Conduction
Such movement of these free electrons creates an electric current
Materials with large numbers of free electrons are called electrical conductors. They conduct electrical current.
Movement of the electrons physically from one place to another is slow. Transfer of the energy from one electron to another happens fast.

38. Conductors and Insulators
In conductors, electric charges are free to move through the material. In insulators, they are not.
In conductors:
The charge carriers are called free electrons
Only negative charges are free to move
When isolated atoms are combined to form a metal, outer electrons of the atoms do not remain attached to individual atoms but become free to move throughout the volume of the material

39. Other Types of Conductors
Electrolytes
Both negative and positive charges can move
Semiconductors
In-between conductors and insulators in their ability to conduct electricity
Conductivity can be greatly enhanced by adding small amounts of other elements
Requires quantum physics to truly understand how they work

40. Simple Circuits Don’t let the name fool you
Bottom line: For electric current to flow, there has to be a complete pathway for it…a complete circuit.

41. Closed and Open Circuits
Closed Circuit - an unbroken path of conductors through which electric current flows
Open Circuit - a circuit with a break in the conductive path, so no current flows

42. Series Circuits
An electrical circuit with only one path for the electrical current to follow

43. Parallel Circuits
An electrical circuit that provides more than one path for the electrical current to follow.

44. Static Electricity
Who hasn’t rubbed a balloon on their hair and stuck it to the wall?
Buildup of charge (static, not moving)
in one place.
Charge can be either positive or negative