Energy generation What does copper wire and magnets have to do with 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 u

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.

The movement of charges such

as electrons is called current, and

this electrical current is what

powers household appliances

Electric Current =

Charge PassingThrough A Given Area

Time

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!

Electric current generation - whether from fossil fuels, nuclear, renewable fuels, or other sources is usually

based on the:

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

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

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!

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!

- AC of 60 Hz produced by generator

- Resistance losses are smallest at high voltages and low currents

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

Where does the motion needed to keep the copper wire moving relative

to the magnetic field come from?

Wind generatedKilronan Wind Farm In Ireland

-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

-North Dakota with 20 times the wind potential of California has not

erected a single wind turbine

Wind power classes 3 (300-400 W/m2) to 7 (800-2000 W/m2) are suitable

for wind power development

-Wind variability must be overcome by system design

- Basic energy Storage

- 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

Water generated - HydroelectricShasta Dam In California

-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

- Hydroelectricity has dropped from producing 30 % to 10% of US electricity

- Large fluctuations in output are mainly due to variable rainfall totals

-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

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

Oil Drilling PlatformCook Inlet, Alaska

-total world production in 1996 of

petroleum is 62,239e3 barrels / day

-an average well in the US produces

only 11 barrels / day

-In Saudi Arabia an average well

produces 9600 barrels /day

Nuclear PowerDiablo Canyon - California

-Plant electrical output 1220 MW

-Plant efficiency 34%

-There are 109 power reactors in the United States

-Produce 22% of nation’s electricity

- In France 79% of electricity comes from nuclear reactors

-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 are 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

-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

Proportion of World’s energy

consumption - 1997

Proportion of the world’s

Electricity generation - 1997