alternative energy sources <ul><li>Interruption </li></ul><ul><li>I was interesting of this topic because in our modern industrial society we consume vast amounts of energy to make our daily life more comfortable, productive and enjoyable. This topic is very global and vast so I decided to tell in short about all kind of alternative energy sources and discuss only technical and ecological sides of subject (no economical, no geographical etc.). </li></ul><ul><li>All of us use energy every day - for heat and light in living and working areas, cooking, transportation, manufacturing, and entertainment. The choices we make about how we use energy - turning machines off when we’re not using them or choosing to buy energy efficient appliances - impact our environment and our lives. </li></ul><ul><li>Energy comes from several different sources. These sources can be split into two main categories: non-renewable and renewable . Non-renewable types of energy include the three major types of fossil fuels – coal, oil and natural gas. Fossil fuels supply more than 90% of the world's energy. Oil leads with a share of about 40 percent of total world energy consumption, followed by coal (24 percent) and natural gas (22 percent). All of these are burned to produce power. </li></ul><ul><li>Fossil fuels are relatively easy to use to generate energy because they only require a simple direct combustion. However, a problem with fossil fuels is their environmental impact. Not only does their excavation from the ground significantly alter the environment, but their combustion leads to a great deal of air pollution. For example, carbon dioxide ( CO2 ) from burning fossil fuels is the largest source of greenhouse gases from human activities. Extra greenhouse gases we are putting into the atmosphere are causing global warming and climate change. Besides, these are fuels that are being consumed more rapidly than they are being replaced. That means that someday we could run out of these fuels. </li></ul><ul><li>Another nonrenewable source is uranium. Uranium is an element that gives us nuclear energy by splitting an atom's nucleus, and this process is called fission. Nuclear energy is a better source of energy because it doesn't put carbon dioxide into the atmosphere. But like all industrial processes, nuclear power generation has by-product wastes: tremendous steam of radioactive products and heat. Hazardous wastes and the possibility of a nuclear disaster are the principal concerns for nuclear power. </li></ul><ul><li>With the growing concerns over the environmental problems today (air pollution, global climate change, massive flooding in river systems, etc.) and the price of non-renewable energy sources soaring, we have to take a closer look at the alternative energy sources . Alternatives to the fossil fuels and nuclear power are renewable sources of energy and they are considerably more attractive in many ways. Renewable sources are derived and replenish quickly from nature and usually do not pollute our environment when used to generate electricity. The five renewable sources used most often include hydropower (water), solar, wind, biomass, and geothermal. </li></ul>
alternative energy sources wind energy geothermal energy alternative energy sources hydropower (water) energy solar power biomass energy
alternative energy sources <ul><li>Solar energy. In the context of renewable energy, solar power is associated with the harnessing of the sun's present emissions of heat or light. There are a variety of types of technologies that can do this. Solar energy is typically divided into three categories: passive solar , active solar , and photovoltaic (electrical ) solar energy . All of them produce solar energy, but in very different ways. </li></ul><ul><li>In active solar category the solar energy is directly converted in the application form. One of the simplest and economical ways to utilize solar energy is through solar thermal systems. Solar thermal technology is employed for collecting and converting the sun energy to heat energy for application such as water and air heating, cooking and drying, steam generation, distillation, etc. </li></ul><ul><li>Solar thermal technologies include solar heat collectors (flat-plate collectors, evacuated-tube collectors) and solar concentrating collectors. Flat-plate collectors are the most commonly used type of collector today. A typical flat-plate collector consists of a box containing a sheet of metal painted black, which absorbs the suns energy. In the most common design, built in pipes in the box carry liquids that take the heat from the box and bring it into the building. This heated liquid, usually a water-alcohol mixture to prevent winter freezing, is used to heat water in a tank or is put through radiators to heat the air. Solar heat collectors sit on the rooftops of buildings and are generally used in hotels and homes. </li></ul><ul><li>Solar concentrating collectors (parabolic concentrators) use mirrors and lenses to concentrate and focus sunlight onto a receiver mounted at the system's focal point. The receiver absorbs and converts the sunlight into heat. This heat is then transported by means of a heated fluid (either water or molten salt) through pipes to a steam generator or engine where it is converted into electricity. There are also large centralized solar power plants, known as "power towers". Power tower is a large tower surrounded by small rotating (tracking) mirrors called heliostats. These mirrors align themselves and focus sunlight on the receiver at the top of tower, collected heat. This focused heat turns water into steam that is used to power a generator. Solar concentrating systems produce high temperatures that can be used for industrial purposes. </li></ul>The Sun’s energy The solar heat collector.
alternative energy sources <ul><li>Photovoltaic (electrical) solar technologies directly convert solar radiation into electricity through the use of photovoltaic cells (PVs), also called solar cells. Photovoltaic or solar electric panels use semiconductor materials such as silicon to convert sunlight to electricity. Most solar cells are made from silicon because it is, so far, the most cost-effective material. Sunlight is composed of light energy in the form of photons. When these photons strike the cell, some electrons in the cell material absorb sufficient energy to break away from their atoms and flow through the material to produce electricity. This electricity can either be used directly as it is or can be stored in the battery. The stored electrical energy then can be used at night. </li></ul><ul><li>Passive solar energy is energy or warmth obtained without any mechanical intervention. The most common of the passive solar technologies is referred to as direct solar gain. A direct gain system includes south-facing large windows that allow the sun's rays to heat surfaces inside the building. The result is that in cold weather the surfaces absorbs solar energy and radiates heat throughout the room. </li></ul><ul><li>Solar energy demand has grown at about 25% per annum over the past 15 years but it has clearly not reach its full potential. The main reason for the lack of mass exploitation of solar power technologies is economic. In order for widespread generation of electricity using solar panels to be feasible it needs to be economically advantageous. In order for solar panels to be an economically viable choice for the production of electricity, production costs must go down and efficiency of the final product must go up. </li></ul>Solar base in USA, Texas
alternative energy sources <ul><li>Hydropower (water) energy - uses the force of moving water to produce electricity. Thousands of years ago the Greeks used water wheels that used the weight of water to move machinery to grind grain and pump water. </li></ul><ul><li>Prior to the widespread availability of commercial electric power, hydropower was used for irrigation, and operation of various machines, such as watermills, textile machines, and sawmills. A tromps produces compressed air from falling water, which could then be used to power other machinery at a distance from the water. </li></ul><ul><li>There are several forms of water power: * Waterwheels, used for hundreds of years to power mills and machinery * Hydroelectricity, usually referring to hydroelectric dams, or run-of-the-river setups (e.g. hydroelectric-powered watermills). * Dam less hydro, which captures the kinetic energy in rivers, streams and oceans. * Tidal power, which captures energy from the tides in horizontal direction * Tidal stream power, which does the same vertically * Vortex power, which creates vortices which can then be tapped for energy * Wave power, which uses the energy in waves. </li></ul><ul><li>About 20 per cent of the world’s electricity is generated through the use </li></ul><ul><li>of water . Today’s hydro - electric power station has a simpler design than </li></ul><ul><li>a conventional coal - fired station . Basically, the hydro - electric plant consists </li></ul><ul><li>of a water turbine which converts the energy from flowing water into </li></ul><ul><li>mechanical energy . Then, an electric generator converts this mechanical </li></ul><ul><li>energy into electrical energy . </li></ul>The hydroelectric power station
alternative energy sources Hydro - electricity is a renewable resource because it is continually produced by the movement of fresh water from rivers and lakes . Hydro - electric power stations are situated where they can take advantage of the greatest fall of a large quantity of water . This is normally at the bottom of a deep and steep - sided valley or gorge, or near the base of a dam . The amount of electrical energy that can be generated from a water source depends on two things; the distance that the water has to fall ( the head ) and the quantity of water flowing . Hydro - electric power stations usually require water storage schemes . It is necessary to store water to ensure a reliable supply of electricity can be generated from water energy whenever it is needed . These hydro - electric schemes address a basic problem with electricity : once it’s generated, it has to be used immediately and it can’t be stored . In hydro - electric schemes, the potential energy of water can be stored in dams or river systems and released to generate electricity as and when it’s required. The hydroelectric power station The principle of work the hydroelectric power station .
alternative energy sources <ul><li>Wind energy - ancient energy source that has moved into the modern era. As long ago as 5000 BC sails were used to travel down the Nile, and windmills were used by the Persians to move water and grind grain, maybe as long as 1,500 years ago. </li></ul><ul><li>Today advanced aerodynamics research has developed wind turbines that can produce electricity. Wind energy uses the energy in the wind for practical purposes like generating electricity, pumping water, or grinding grain. Wind turbines are used around the world for many applications. They use ranges from homeowners with single turbines to large wind farms with hundreds of turbines providing electricity to the power grid. Though wind turbines are expensive in the first place, the wind energy to keep them going is free. It is actually easier and faster to build a wind farm than to build a fossil fuel plant or hydro-electric dam to generate the same amount of electricity. As with solar energy, wind energy will never run out, and no country can ever refuse to share its supply of wind. Best of all, wind power causes no damage to the environment except the sight of so many windmills gathered in the same place! </li></ul>The wind farms
alternative energy sources <ul><li>Geothermal energy - derived from hot dry rocks, magma, hot water springs, natural geysers, etc. It is a clean, renewable resource that provides energy around the world in a variety of applications and resources. Although areas with telltale signs like hot springs are more obvious and are often the first places geothermal resources are used, the heat of the earth is available everywhere, and we are learning to use it in a broader diversity of circumstances. It is considered a renewable resource because the heat emanating from the interior of the Earth is essentially limitless. The heat continuously flowing from the Earth’s interior, which travels primarily by conduction, is estimated to be equivalent to 42 million megawatts (MW) of power, and is expected to remain so for billions of years to come, ensuring an inexhaustible supply of energy. A geothermal system requires heat, permeability, and water. The heat from the Earth's core continuously flows outward. Sometimes the heat, as magma, reaches the surface as lava, but it usually remains below the Earth's crust, heating nearby rock and water — sometimes to levels as hot as 700°F. When water is heated by the earth’s heat, hot water or steam can be trapped in permeable and porous rocks under a layer of impermeable rock and a geothermal reservoir can form. </li></ul>Hot Springs in Steamboat Springs, Nevada. The Geothermal energy source. The Formation of a Geothermal Reservoir
alternative energy sources <ul><li>This hot geothermal water can manifest itself on the surface as hot springs or geysers, but most of it stays deep underground, trapped in cracks and porous rock. This natural collection of hot water is called a geothermal reservoir. </li></ul><ul><li>Geothermal energy can be used for electricity production, for commercial, industrial, and residential direct heating purposes, and for efficient home heating and cooling through geothermal heat pumps. </li></ul>The Geysers, CA, Dry Steam Plant Geothermal electricity . To develop electricity from geothermal resources, wells are drilled into a geothermal reservoir . The wells bring the geothermal water to the surface, where its heat energy is converted into electricity at a geothermal power plant. Geothermal heat is used directly, without involving a power plant or a heat pump, for a variety of applications such as space heating and cooling, food preparation, hot spring bathing and spas ( balneology ) , agriculture, aquaculture, greenhouses, and industrial processes. The Romans used geothermal water to treat eye and skin disease and, at Pompeii, to heat buildings . Medieval wars were even fought over lands with hot springs . The first known " health spa " was established in 1326 in Belgium at natural hot springs . And for hundreds of years, Tuscany in Central Italy has produced vegetables in the winter from fields heated by natural steam. For a video presentation on the different ways to use geothermal energy you can visit http://geothermal.marin.org/video/vid_pt5.html . The geothermal power plant, Iceland
alternative energy sources <ul><li>Biomass energy - biomass refers to straw, wood, biological waste products such as manure, and other natural materials that contain stored energy. The energy stored in biomass can be released by burning the material directly, or by feeding it to micro-organisms that use it to make biogas, a form of natural gas. Of all the forms of energy-as-fuel, biomass, a fuel source made from plants and animals, is one of the most renewable. It includes lumbar industry residues such as wood and sawdust, agricultural and food processing wastes, sewage and solid waste, and other organic materials. The total annual production of biomass is estimated to be about eight times the total annual world consumption of energy from all current sources. This makes biomass a huge, largely untapped energy source. </li></ul>
alternative energy sources Biomass has become an important renewable energy source throughout the world. It is a form of chemical energy , which is energy stored in the bonds of atoms and molecules. This chemical energy in biomass is converted into other forms of energy to be used by mankind. Traditional biomass energy sources, including wood, provided about 14 per cent of the world’s primary energy supplies in 2005. In United States, biomass was the second-most common form of renewable energy in 2005, providing enough electricity to power more than two million homes . Bioenergy is the conversion of chemical energy – which is stored in the biomass - into an industrially useful form, such as heat or electricity . Through bioenergy, we can produce electricity from biomass materials such as trees, grass cuttings, sugars and vegetables . However, the practical development of bioenergy is still relatively costly. . The biomass cycle
alternative energy sources <ul><li>Conclusion </li></ul><ul><li>So, no single solution can meet our society's future energy needs. The solution instead will come from the family of energy technologies that do not deplete our natural resources or destroy our environment. That’s the final decision that the nature imposes. Today mankind’s survival directly depends upon how quickly we can renew the polluting fuel an energy complex we have now with sound and environmentally friendly technologies. </li></ul><ul><li>Certainly, alternative sources of energy have their own drawbacks, just like everything in the world, but, in fact, they seem minor in comparison with the hazards posed by conventional sources. Moreover, if talking about the dangers posed by new energy technologies, there is a trend of localization. Really, these have almost no negative global effect, such as air pollution. </li></ul><ul><li>Moreover, even the minor effects posed by geothermal plants or solar cells can be overseen and prevented if the appropriate measures are taken. So, when using alternatives, we operate a universal tool that can be tuned to suit every purpose. They reduce the terrible impact the human being has had on the environment for the years of his existence, thus drawing nature and technology closer than ever before for the last 2 centuries. </li></ul>
alternative energy sources <ul><li>Keywords : </li></ul><ul><li>חלופי alternative - לבקע , לפלג , לפצל - to split לא ניתן לחידוש - non-renewable ניתן לחידוש - renewable מאובן - fossil דלק ( חומר ) - fuel שריפה - combustion חפירה - excavation לשנות , לתקן - to alter חממה - greenhouse ביקוע , התפלגות - fission מסוכן - hazardous לזהם - to pollute אנרגית שמש - solar energy שילוח , פליטה - emission לנצל , למצוא שימוש ל - to utilize צינור פינוי - evacuated-tube סדין , דף , לוח - sheet מכל - tank מוקדי , מרקזי - focal תחנת כוח , מנוע - power-plant התנהגות פסולה , ניהול כושל - misconduct אסכלה , רשת חשמל - grid מפרק שורש כף היד - wrist חללית - spacecraft חמימות - warmth טוב , נעים , נוח , ממאיר - benign אפשרי , סביר , בר - ביצוע - feasible </li></ul>
alternative energy sources <ul><li>References : ( 1) U.S. DOE Energy Efficiency and Renewable Energy . 01 Mar. 2008. U.S. Department of Energy. (6 Apr. 2009) < http://www.eere.energy.gov />. </li></ul><ul><li>(2) Renewable Energy Policy Project . Jan. 2000. REPP. 25 Mar. 2009 < www.repp.org />. </li></ul><ul><li>(3)"Water energy." World of Energy . 27 Feb. 2007. Western Power. (25 Mar. 2009) < http://www.worldofenergy.com.au >. </li></ul><ul><li>(4) “Geothermal energy." World of Energy . 27 Feb. 2007. Western Power. (25 Mar. 2009) < http://www.worldofenergy.com.au >. </li></ul><ul><li>(5) Geothermal Energy Association . Jan. 2007. GEA. (25 Mar. 2009) < http://www.geo-energy.org/aboutGE/basics.asp >. </li></ul><ul><li>Bibliography: </li></ul><ul><li>Farret, Felix A., and Godoy Simoes. “Integration of Alternative Sources of Energy.” Chapter 1 – “Alternative Energy Sources”; John Wiley & Sons, Inc., 2006. </li></ul>