GEOL 108Lg 1st Edition Lecture 22Outline of Last Lecture-Energy and Economy-Fossil FuelsOutline of Current Lecture- Renewable and Alternative EnergyCurrent LectureRenewable energy is energy that comes from natural resources such as sunlight, wind, rain, tides,waves and geothermal heat. Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.Prior to the development of coal in the mid-19th century, all energy used was renewable, with the primary sources being human labor, animal power in the form of oxen, mules, and horses, water power for mill power, wind for grinding grain, and firewood. A graph of energy use in the United States up until 1900 shows oil and natural gas with about the same importance in 1900 as wind and solar played in 2010.Wind Energy - A Little History-People first built windmills to grind their grain. - The earliest known windmills were in Persia (Iran).WindWind power is currently the number one alternative energy source. Large mega-watt wind turbines are currently being constructed off the coasts of northern Europe to supply countries like Germany and Denmark with enough electrical energy to supply nearly 20% of their current needs. Wind is also completely renewable as long as there is wind.Wind Energy5-Fastest growing energy segment in the world and has been so for 25 years.5-Cost of wind power has dropped by 90%.5-In the next 20 years, wind energy will be a top competitor for energy provision.5-BUT: need different kind of power grid, kills birds, aesthetically displeasing A wind turbine is a device that converts kinetic energy from the wind, also called wind energy, into mechanical energy; a process known as wind power. If the mechanical energy is used to produce electricity, the device may be called wind turbine or wind power plant. If the mechanicalenergy is used to drive machinery, such as for grinding grain or pumping water, the device is called a windmill or wind pump. Similarly, it may be called wind charger when it is used to chargebatteries.The result of over a millennium of windmill development and modern engineering, today's wind turbines are manufactured in a wide range of vertical and horizontal axis types. The smallest turbines are used for applications such as battery charging or auxiliary power on boats; while large grid-connected arrays of turbines are becoming an increasingly important source of wind power-produced commercial electricity.Hydroelectric Energy (Aka Hydroelectricity)●Falling water, our largest renewable resource next to wood, has been used as an energy source for thousands of years.●First used in early 1900’s, today it provides a fourth of the world’s electricity.●Very inexpensive. Cheapest source of alternative power.●Currently at maximum, with downstream consequences.Most hydroelectric power comes from dammed water (dams). The power extracted from the water depends on the volume and on the difference in height between the source and the water's outflow. This height difference is called the head. The amount of potential energy in water is proportional to the head. A large pipe (the "penstock") delivers water to the turbine.Other categories:Pumped-storageThis method produces electricity to supply high peak demands by moving water between reservoirs at different elevations. At times of low electrical demand, excess generation capacity isused to pump water into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently provide the most commercially important means of large-scale grid energy storage and improve the daily capacity factor of the generation system.Run-of-the-river hydroelectricity Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that the water coming from upstream must be used for generation at that moment, or must be allowed to bypass the dam.Tide PowerA tidal power plant makes use of the daily rise and fall of ocean water due to tides; such sources are highly predictable, and if conditions permit construction of reservoirs, can also be dispatchable to generate power during high demand periods. Less common types of hydro schemes use water's kinetic energy or undammed sources such as undershot waterwheels.Underground power stationsAn underground power station makes use of a large natural height difference between two waterways, such as a waterfall or mountain lake. An underground tunnel is constructed to take waterfrom the high reservoir to the generating hall built in an underground cavern near the lowest point of the water tunnel and a horizontal tailrace taking water away to the lower outlet waterway.Solar Energy5Solar=Direct Energy Effective warming for household use5Current technology becoming less expensiveIncludes:1) low energy (heated water panels)2) high (photovoltaic cells)3) extreme (concentrated sun light)Solar energy is the cleanest and most abundant renewable energy source available, and the U.S. has some of the richest solar resources in the world. Modern technology can harness this energy for a variety of uses, including generating electricity, providing light or a comfortable interior environment, and heating water for domestic, commercial, or industrial use.Diagram of how it works: Concentrated Solar Energy (Barstow, CA)Converting water to steam and powering a marine base.PhotovoltaicsConventional solar modules turn sunlight into electricity using a semiconductor known as polycrystalline silicon. That's the same material used in computer chips. Until recently, it had been pricey and in short supply.Companies like First Solar use a lower-cost semiconductor known as cadmium telluride, which it fashions into so-called thin-film cells that are cheaper to manufacture than their silicon-based counterparts.Yes, cadmium is toxic!Geothermal Energy Diagram: How Energy is Generated and UsedTIDAL POWER•A dam or barrage is built across an estuary or bay that experiences a significant tidal range (more than 5 meters). The purpose of this dam or barrage is to let water flow through it into the basin as the tide comes in. The barrage has gates in it