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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.

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Presentation on theme: "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."— Presentation transcript:


2 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 The movement of charges such as electrons is called current, and this electrical current is what powers household appliances. Electric Current = Charge Passing Through A Given Area ------------------------------- Time

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

6 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 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!

8 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 - AC of 60 Hz produced by generator - Resistance losses are smallest at high voltages and low currents

10 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 Where does the motion needed to keep the copper wire moving relative to the magnetic field come from? Wind generated Kilronan Wind Farm In Ireland -attains between 50 – 70% efficiency - one windmills 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

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

13 -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

14 Water generated - Hydroelectric Shasta 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.


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

17 -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

18 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


20 Oil Drilling Platform Cook 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



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


25 -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.

26 -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

27 Proportion of Worlds energy consumption - 1997 Proportion of the worlds Electricity generation - 1997



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