Managing Energy Assets with a Wind Turbine - Essay Example

?Managing Energy Assets with a Wind Turbine Scientists and industry experts may argue over how long the world’s supply of oil and natural gas will last, but it will end because the future belongs to renewable energy. Although generally more pricey than conventionally produced supply, renewable energy helps reduce pollution and conserve fossil fuels. Alternative power source comes from natural resources and is generally inexhaustible such as solar, wind, tidal, and geothermal heat. Wind as an Alternative Energy Source To use wind energy successfully, one should have the right site and select the right machine. In wind power generation, there are no harmful by-products left over since no chemical processes take place. Also, with wind power, pollution that can contaminate the environment is avoided. Since wind generation is a renewable source of energy, we will never run out of it. Farming and grazing can still take place on land occupied by wind turbines which can help in the production of biofuels. Wind farms can be built off-shore like that in Germany and at some states of the United States of America. Wind energy harnesses the power of the wind to propel the blades of wind turbines. A turbine is a machine powered by rotating blades. The rotation of turbine blades is converted into electrical current by means of an electrical generator. In the older windmills, wind energy was used to turn mechanical machinery to do physical work, like crushing grain or pumping water. Wind towers are usually built together on wind farms. Now, electrical currents are harnessed by large scale wind farms that are used by national electrical grids as well as small individual turbines used for providing electricity to isolated locations or individual homes (Layton, 2006).  History of Wind Power Technology In the beginning, wind power production did not have any impact on the power system control. When it started in the 1980’s production was a few tens of kW, and today, multi-MW range wind turbines are being installed. This also means that wind power production in the beginning did not have any impact on the power system control, but now they have to play an active part in the grid due to their size. The technology used in the past wind turbines was based on a squirrel-cage induction generator connected directly to the grid. With that, there is no control of the active and reactive power, which typically are important control parameters to regulate the frequency and the voltage. The power pulsations in the wind are almost directly transferred to the electrical grid. As there is an increase in the power range of the turbines, the control parameters become more important and likewise, necessary to introduce power electronics as an interface between the wind turbine and the grid. The power electronics is changing the basic characteristic of the wind turbine from being an energy source to be an active power source. The electrical technology used in wind turbine is not new. It has been discussed for several years but now the price per produced kWh is so low, that solutions with power electronics are very attractive (Blaabjerg & Chen, 2005) . Wind Turbines Stored energy is referred to as potential energy, while energy in motion is called kinetic energy. Kinetic energy can be captured, just like the energy in the moving water that can be captured by the turbine in a hydroelectric dam. In the case of a wind turbine, the turbine blades are designed to capture the kinetic energy in wind. Modern wind turbines fall into two basic groups; the horizontal-axis variety, like the traditional farm windmills used for pumping water, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor. Most large modern wind turbines are horizontal-axis turbines. In any wind-energy turbine, the three crucial parts are the rotor blades, the shaft, and the generator (Sudrai & Chindris, 2005). The rotor blades act as barriers to the wind, such that when the wind forces the blades to turn, kinetic energy is transferred to the rotor. The air flow around a wind turbine blade is completely dominated by the head wind from the rotational movement of the blade through the air. The blade aerodynamic profile produces lift because of its streamlined shape. The rear side is more curved than the front side. The lift effect on the blade aerodynamic profile causes the forces of the air to point in the correct direction. Determining the width, thickness, and twist of a blade is a compromise between the need for streamlining and the need for strength (Steisdal, 1999). The shaft is connected to the center of the rotor, such that when the rotor spins, the shaft spins as well. Through this, the rotor transfers its mechanical, rotational energy to the shaft. At constant shaft speed, in step with the grid, the angle of attack increases with increasing wind speed. The blade stalls when the angle of attack exceeds 15 degrees. In a stall condition the air can no longer flow smoothly or laminar over the rear side of the blade, lift therefore falls and drag increases.The other end of the shaft connects to the electrical generator (Steisdal, 1999). The generator converts the mechanical energy into electricity. In the simplest set-up: When the turbine blades capture wind energy and start moving, they spin a shaft that leads from the hub of the rotor to a generator. The generator turns that rotational energy into electricity. At its essence, generating electricity from the wind is all about transferring energy from one medium to another (Steisdal, 1999). Aside from the three crucial parts of a wind turbine, the modern design includes the following parts: Nacelle, which is the casing containing : gearbox - this device increases speed of shaft between rotor hub and generator electronic control unit - responsible for monitoring the system, shutting down the turbine in case of malfunction, and control of yaw mechanism yaw controller - moves the rotor to align with wind direction brakes - allows the shaft to stop its rotation in case of power overload or system failure, and generator - turns that rotational energy into electricity; The tower supports the rotor and nacelle, the height of the which lifts entire setup to higher elevation. The electrical equipment carries the electricity from the generator down through tower. The electrical equipment also includes many of the safety elements of a turbine. The electronic interface is the device that sends the power to the batteries, and will shut down the flow of electricity when the batteries are fully charged. Typically, a high-voltage cable will connect the interface to the battery. Operation of a Wind Turbine Generation of electricity from wind energy may have evolved through time but its basic operation has stayed generally the same. According to Sudria (2005), the process starts with the capture of wind through the rotor blades. The energy in the wind is converted to rotational motion by the rotors as exhibited by the turning of the blades (rotation). When the blades turn, the rotor turns a shaft, which transfers the motion in to the nacelle. The slowly rotating shaft enters a gearbox that greatly increases the rotational shaft speed. The output shaft is connected to a generator that converts the rotational movement into electricity at medium voltage (hundreds of volts). The electricity flows down heavy electric cables inside the tower to a transformer, which increases the voltage of the electric power to the distribution voltage. At this point, the electric voltage has now reached to thousands of volts. The distribution - voltage power flows through underground lines to a collection point where the power output may be combined with the power output of other turbines. From here, the electricity can be utilized by sending it to nearby farms, residences, and towns. The electricity may also be sent to a substation where the voltage is all the more increased to transmission - voltage power, or up to hundreds of thousands of volts, and sent through above - ground transmission lines to distant cities and factories (Sudrai & Chindris, 2005). Wind turbines are often grouped together into a single wind power plant, also known as a wind farm, and generate bulk electrical power. Electricity from these turbines is fed into a utility grid and distributed to customers, just as with conventional power plants. New wind turbine technology integrates power electronics and control, making it possible for wind power generation to participate in active and passive power control. Thus, exact modelling of wind turbine systems is required, in order to simulate wind turbine behaviour during the modification of the network operation point (Sudrai & Chindris, 2005). “Disadvantages” of Wind-Generated Electricity Cost Issues The technology does require a higher initial investment than fossil-fueled generators, although, the cost of wind power has decreased dramatically in the past decade. Up to eighty per cent of the cost is machinery, however, since there is no fuel to purchase and operating expense is minimal, costs of wind-generated energy are much more competitive with other generating technologies (Wind Energy Development Programmatic EIS). Environmental Concerns Compared to fossil fuel power plants, wind power plants have relatively little impact on the environment. However, there is some concern over the noise produced by the rotor blades, aesthetic impacts, and birds and bats having been killed by flying into the rotors. Most of these problems have been greatly reduced, if not completely resolved, through technological development or by proper placement of wind plants (Wind Energy Development Programmatic EIS). Supply and Transport Issues Intermittent power supply is the major challenge to using wind as a source of power. Wind cannot be stored, but wind-generated electricity can be stored if batteries are used. Not all winds can be harnessed to meet the timing of electricity. Further, good wind sites are often located in remote locations far from areas of electric power demand (such as cities). Finally, wind resource development may compete with other uses for the land, and those alternative uses may be more highly valued than electricity generation. However, wind turbines can be located on land that is also used for grazing or even farming (Wind Energy Development Programmatic EIS). Monitoring and Maintenance A wind turbine averages to a life span of twenty years. Within this life span, exposure to the most extreme operating conditions on the planet is unavoidable. However, operators should act to reduce uncertainties regarding the reliability of equipment. Optimum capacity and long-term profitability can be achieved with proactive maintenance (George, 2009). When equipment fails, wind farms must deal with exorbitant crane mobilization expenses, lost energy production, soaring costs per kilowatt-hour and untimely delays in obtaining replacement parts in a burgeoning industry where the demand for necessary components routinely outstrips supply. Condition Monitoring A strategy whereby physical parameters are measured regularly to determine equipment condition is called condition monitoring. Physical parameters include vibration, temperature, lubrication particles and others. An integrated on-line condition monitoring system within a wind turbine nacelle offers a powerful tool for managing day-to-day maintenance routines and consolidating risky, costly maintenance activities. These systems pay off for wind farms by allowing operators to monitor and track failing component conditions in real-time. Maintenance decisions, therefore, is based on actual machine conditions instead of arbitrary maintenance schedules. Among the operating conditions that can be targeted for early detection, diagnosis and remedial action: unbalanced turbine blades, misalignment, shaft deflections, mechanical looseness, foundation weakness, bearing condition, gear damage, generator rotor/stator problems, resonance problems, tower vibrations , blade vibrations , electrical problems, and inadequate lubrication (George, 2009). Automatic lubrication  Timely and effective lubrication helps to reduce wear, minimize lubricant use, maximize efficiency and reduce unscheduled downtime. Centralized automatic grease lubrication systems can contribute their own reliability benefits when it delivers exact and clean quantities of appropriate lubricant at the right positions at the right time. Refilling the lubrication reservoir and occasionally inspect the connected lubrication points are the only requirement in this maintenance activity. As such, the problems associated with excessive lubrication can vanish; lubricant consumption can fall over time; maintenance time, energy and costs can diminish; more informed and timely decisions can be made for lubricant purchases; and operational reliability can be improved. When planning, installing and—afterwards—implementing a centralized lubrication system inside a wind turbine, remember to consider monitoring systems that can be integrated with the lubrication system (George, 2009). There are more solutions that can be offered by the experts in the many interrelated aspects of wind turbine technology allowing the wind turbine operators access to the most current engineering resources to help keep the rotors running energetically. Other Components Making Up the Wind Turbine Installation Before the installation of turbines, the developer will assess the wind resource at a particular site by collecting meteorological data, determining access to transmission lines, and considering environmental and community impacts. As soon as sufficient wind resources are found, the developer will secure land leases from property owners, then obtain the necessary permits and financing, and then purchase and install wind turbines. The completed facility is often sold to an independent operator or an independent power producer who generates electricity to sell to the local utility, although some utilities own and operate wind farms directly (Burton, 2001). Aside from the collection of wind speed data, a careful assessment of the proposed site should be undertaken. To ensure that the turbine foundations, access roads and construction areas be provided at reasonable cost, ground conditions at the site need to be investigated. A visual and landscape assessment is required, as well as noise assessment. Sound produced by these structures, and how it affects the nearest dwellings should be looked into. It is even necessary to establish a baseline level of noise in the area so that realistic assessments can be conducted. The impact of the wind turbine structure, as well as its construction, on the local flora and fauna (even migrating birds and mammals) needs to be considered. Depending on the site, it may be necessary to evaluate the impact of the project on water courses and water supplies. The proximity to airfields or military training areas needs to be considered carefully (Zavadil, 2003). Implementing a small wind turbine system for your own needs is one way to guarantee that the energy you use is clean and renewable. A residential or business turbine setup can cost anywhere from $5,000 to $80,000. A large-scale setup costs a whole lot more. A single, 1.8-MW turbine can run up to $1.5 million installed, and that's not including the land, transmission lines and other infrastructure costs associated with a wind-power system. Overall, wind farms cost in the area of $1,000 per kW of capacity, so a wind farm consisting of seven 1.8-MW turbines runs about $12.6 million. The "payback time" for a large wind turbine -- the time it takes to generate enough electricity to make up for the energy consumed building and installing the turbine -- is about three to eight months, according to the American Wind Energy Association (Walker, 2004). Walker of the National Geographic News reported in 2004, “To date worldwide around 50,000 MW of wind energy capacity has been installed generating around 100TWh of electricity annually and employing 100,000 people. That is saving as much as 80 million tonnes of carbon dioxide every year and meeting the domestic electricity needs of more than 45 million people. In the UK alone there are 1578 turbines, with a total installed capacity of 1090MW - enough to provide power for over 600,000 homes and reduce carbon emissions by nearly 2.5 million tonnes per year. Countries like Denmark and Germany are even further ahead, with wind power playing an even great role in meeting their climate change targets.” With regards to how the structures have affected nearby communities, there has been no health implication of living near a wind farm. In 25 years of wind generation and with more than 68,000 turbines worldwide there have been no reports of health issues. Wind turbines do not produce emissions, harmful pollutants or waste products. The level of noise (including low frequency noise/infrasound) is anticipated to be low for the closest households and below threshold limits set by the UK government. Changes to wind farm technology mean that mechanical noise from turbines has been reduced over the years despite the much larger capacity machines which have evolved. In close proximity to a turbine, the main sound is the swoosh of the blades passing the tower, but this effect lessens with distance. Outside the dwellings nearest to the proposed wind farm the sound of the turbines generating electricity will be within strict limits set down in government guidance issued by the Department for Trade and Industry and explained in detail in our Application. These guidelines on wind turbines and noise emissions are designed to ensure the protection of people living nearby. However, the best way to find out is to go and visit a development, which many operators encourage. Beauty is in the eye of the beholder, and whether a wind turbine is attractive or not will always be a personal opinion. However, studies regularly show that most people find turbines an interesting feature of the landscape. On average 80% of the public support wind energy, less than 10% are against it, with the remainder undecided. Surveys conducted since the early 1990's across the country near existing wind farms have consistently found that most people are in favour of wind energy, with support increasing among those living closer to the wind farms. There is no evidence on negative impacts of wind farms on tourism. The UK's first commercial wind farm at Delabole received 350,000 visitors in its first ten years of operation, while 10,000 visitors a year come to take the turbine tour at the Ecotech Centre in Swaffham, Norfolk. A recent MORI poll in Scotland showed that 80% of tourists would be interested in visiting a wind farm. Wind farm developers are often asked to provide visitor centres, viewing platforms and rights of way across their sites. There is currently no evidence in the UK showing that wind farms impact long term house prices, and there is some local evidence (RICS survey) to suggest that the presence of a wind farm has no real effect on prices. In fact, there is evidence following a comprehensive study by the Scottish Executive that those living nearest to wind farms become their strongest advocates. The RSPB stated in its 2004 information leaflet Wind farms and birds, that "in the UK, we have not so far witnessed any major adverse effects on birds associated with wind farms". Wind farms are always subject to an Environmental Impact Assessment and developers follow the industry's Best Practice Guidelines and work closely with organisations such as Scottish National Heritage and the RSPB to ensure that wind farm design and layout does not interfere with sensitive species or wildlife designated sites. Moreover, a recent report published in the journal Nature confirmed that the greatest threat to bird populations in the UK is climate change. According to the British Wind Energy Association (the trade and professional body for the UK wind and marine renewables industries) no member of the public has ever been injured by wind energy or wind turbines anywhere in the UK, despite the fact that there are now over 1578 operational wind turbines. There are alternative sources of renewable energy. These include off-shore wind farms, solar power, and wave and tidal power. However, the government is clear that both on-shore and off-shore wind farms are required to achieve agreed targets for renewable energy (BaillieWindFarm, 2007) (Walker, 2004). Bibliography BaillieWindFarm. (2007). Baillie Wind Farm. Retrieved February 7, 2011, from Baillie Wind Farm: http://www.bailliewindfarm.co.uk/communityconsultation.html Blaabjerg, F., & Chen, Z. (2005). Power Electronics in Wind Turbine Systems. Aalborg East: Aalborg University. Burton, T. (2001). Wind Energy: Handbook. Prowis: John Wiley and Sons. George, K. (2009, June 15). Maintenance World. Retrieved January 7, 2011, from Growing Reliability Down on the Wind FArm: http://www.maintenanceworld.com/articles/mt-online/growing-reliability-down-wind-farm.html Layton, J. (2006, August 9). How Stuff Works. Retrieved February 6, 2011, from How Wind Power Works: http://science.howstuffworks.com/environmental/green-science/wind-power.htm Steisdal, H. (1999). Aerodynamics of the Wind Turbine. The Wind Turbine Components and Operation , 5-10. Sudrai, A., & Chindris, M. (2005). Wind Turbine Operation in Power Systems and Grid Connection Requirements. Barcelona: CITCEA. Walker, C. (2004, October 28). National Geographic New. Retrieved February 7, 2011, from The Future of Alternative Energy: http://news.nationalgeographic.com/news/2004/10/1028_041028_alternative_energy_2.html Wind Energy Development Programmatic EIS. (n.d.). Retrieved February 6, 2011, from Wind Energy Basics: http://windeis.anl.gov/guide/basics/index.cfm Zavadil, R. (2003). Wind Generation Technical Characteristics for the NYSERDA Wind Impacts Study. Tennessee: EnerNex Corporation. Read More