Lecture 2 Energy Generation PDF

Lecture 2 GENERATION Prepared by: ENGR. LARA ANDREA D. VILLASANTA, REE, RME 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 ultima...

Lecture 2 GENERATION Prepared by: ENGR. LARA ANDREA D. VILLASANTA, REE, RME 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. OBJECTIVES After studying this unit, you should be able to: Understand the concept of power plant Understand the types of power plants, Know the types of fuels, and Describes the main components of power plants 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 ------------------------------- Electric Current = 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. 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. Generator A generator converts mechanical energy into electrical energy 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. A Question Of Balance  Pros & Cons COAL cheap and abundant but source of greenhouse gases clean HYDRO but seasonal and no new sources cleaner than coal but limited supply NATURAL GAS renewable but expensive, low energy density, SOLAR & WIND and intermittent  Pros & Cons high energy density NUCLEAR no air pollution reliable fuel supply but what about safety, security, and waste?  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 Wind generated in the world. Kilronan Wind Farm In Ireland -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 -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 - 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 -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 Oil Drilling Platform produces 9600 barrels /day Cook Inlet, Alaska -There are 109 power reactors in the United States -Produce 22% of nation’s electricity - In France 79% of electricity comes from nuclear reactors -Plant electrical output 1220 MW Nuclear Power -Plant efficiency 34% Diablo Canyon - California -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  What is Natural Gas? Natural gas is a flammable gas occurring naturally underground, and is often used as a fuel source. It can be used as a source for electricity, however it is largely used in its gaseous form to heat homes. Copyright, legal, version number? 35 How do we Extract and Use Natural Gas? Copyright, legal, version number? 36  Natural Gas Extraction Issues Natural gas extraction has several associated issues. What are some possible environmental consequences from the issues mentioned in the picture? Natural gas extraction can result in dangerous hazards such as explosions and fires. Copyright, legal, version number? 37 END OF DISCUSSION