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понеделник, 10 декември 2012 г. Може ли енергията от вятъра да обезпечи цялото човечество През 2011 година общата численост на енергията произведена от всички ветрогенератори в света съставлява 430 теравата, което се явява 2,5% от цялата произведена от човечеството енергия. На планетата Земя има достатъчно енергия на вятъра, за да обезпечи всички човешки потребности. Какво ще стане, ако ние можем да "включим" целият достъпен вятър? Вятърната енергия или ветроенергетика, това е отрасъл на енергетиката, който се занимава с преобразуването на енергията на въздушните маси в електрическа, механическа или друга необходима енергия. Тази енергия се явява възобновяема за разлика от изкопаемите горива, енергията на вятъра практически е неизчерпаема, повсеместно достъпна и много по-екологична. Използвайки модел за изчисляване на потенциала на вятърната енергия, изследователи от Научния Институт Карнеги (Carnegie Institution for Science) и Ливерморската лаборатория "Лауренс" (Lawrence Livermore National Laboratory), публикували свои резултати в списание "Природни изменения на климата" (Nature Climate Change). По думите на Кейт Марвел, един от съавторите на изследванията с Кейн Калдейра и Бен Кравитц, около нас има достатъчно енергия, както на повърхността на Земята, така и в атмосферата, за да се обезпечи енергия за цялата планета 100 пъти повече от текущата норма. В настоящия момент човешката цивилизация използва примерно 18 теравата енергия. Съгласно показания модел ветровите турбини могат да произведат около 400 теравата вятърна енергия от долните слоеве на атмосферата и около 1800 теравата от горните слоеве. Работата на ветрогенератор с мощност 1 мегават за 20 години позволява да се икономисат примерно 29 хиляди тона въглища или 92 хиляди барела нефт. Действително, вероятно човечеството ще се сблъска и с ограничение на количеството на получаваната по този начин енергия. Вятърните турбини работят по метода на създаване на съпротивление или неговото забавяне, снижавайки силата на вятъра. Ако се поставят прекалено много ветрови турбини, то вятърът значително ще намали скоростта си. Освен това такива изменения в глобалната циркулация на вятъра могат негативно да повлияят на климата (предишното изучаване на подобен модел показало риск от глобално изменение на разпределението на валежите при крупномащабно "събиране" на вятърна енергия.) Въпреки това, както твърдят учените, нито един проблем с изменението на климата няма да ни застрашава още много, много дълго време. Човечеството може екологически безопасно да получава вятърна енергия до 2000 теравата, преди да се сблъска с физическите предели за броя на вятърните турбини, които биха могли да повлияят на силата на вятъра. Тази цифра е 100 пъти по-голяма от реалното потребление на електроенергия на планетата в настоящия момент. Следващата стъпка от изследванията на учените ще бъде коригиране на анализа за техническите възможности на ландшафта за месторазположението на вятърните турбини. Но на този етап може уверено да се каже, че при наличие на такава богата възможност за обезпечаване на човечеството с енергия в пъти превишаваща текущите потребности, то решението за развитие в тази област ще се определя от политически, икономически и технически ограничения, а не от териториални граници. По материали от : http://www.washingtonpost.com Публикувано от it-is-me в 12:59:00 Етикети: зелена енергия Абонамент за: Коментари за публикацията (Atom)
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Wind is moving air, and is a product of the sun. The sun heats up uneven surfaces of the earth, which leads to air, flow from high-pressure environments to low pressure environments. This rapid movement of air is what we know as wind. Wind energy is considered a renewable source of energy, which means that it will never run out. However, it depends on the strength of the winds. Therefore, when there is no wind, places that use wind energy have to rely on other sources of energy. In ancient times wind energy was used to power ships, windmills, sawmills and even to power grinding stones to crush wheat or corn. Today, wind energy is used mainly for electricity generation, although it is also used for producing mechanical energy. Wind energy is harnessed when the kinetic or the moving energy of the wind passes through the blades of wind turbines. It is converted to electricity when this power passes through wind generators. Although they depend on the speed of the wind, they also have a brake that controls the speed at which the blades turn, to prevent damage. Windmills are used for pumping water, and are found mainly in large-scale rural agricultural programmes. Wind turbines are found both on land, but maybe soon found at sea too. Offshore wind turbines have a better chance of consistently providing wind energy because the strength of the wind is far higher at sea than on land, and because there are more obstacles like tall buildings and trees at land that slow down the speed of wind. Wind farms are large areas that include many wind turbines together. These wind farms can produce large amounts of electricity economically because of their advantage of having so many wind turbines in one place. Wind must travel at roughly 12 to 14 miles per hour, or more, to be harnessed into wind energy through turbines. Each wind turbine can produce about 60 – 300 kilowatts of electricity, which is enough to power 3,000 100-watt bulbs. A single turbine can generate enough electricity for a home or school, while a small turbine can power a single house. When the wind energy has produced electricity, this electricity is passed through a transformer to increase its voltage so that it can be sent over longer distances. Choosing an area that is suitable for producing wind energy must be done carefully. The place has to be a place where wind blows fast, without many obstacles and at a high altitude. The best places for wind farms are open planes, on the shore, on top of rounded mountains and mountain gaps. There are two broad categories of wind turbines. The vertical axis wind turbine (VAWTs) and the horizontal axis wind turbine (HAWTs). Although both have various advantages and disadvantages, the HAWTs are more successful than the VAWTs. This is mainly because the VAWTs do not perform as well, and are not as reliable. Scientists are working on improving the technology of the VAWTs because they have large practical applications. HAWTs are large wind turbines that resemble windmills. The blades are similar to the propellers of a plane. They are huge, almost as big as a 20-foot building. The blade span is sometimes as big as a football field. They are built so big and wide, to be able to capture more wind. The blades of the VAWTs move from top to bottom, the opposite of how the HAWT blades turn. VAWTs are about 100 feet tall and are best for areas where the consistency of wind is low. The VAWT does not need to be situated in the path of the wind to produce power, like the HAWT does. The VAWTs have four main designs, the Darrieus wind turbine, the Giromill, the Savonius wind turbine, and the Twisted Savonius. The history of windmills date back to the Persian civilisation in 5000 B. C where they used wind energy to propel boats down the Nile River. China followed later on, around 200 B. C to pump water, during which time the Persian civilisation and the Middle East had already started using VAWTs to grind grain. By the 11th century, knowledge of windmills and how to produce food spread from the Middle East to Europe. The technology arrived in America around the 19th century from the Dutch, and was mainly used to pump water and eventually generate electricity by the late 1930s. There are many reasons why wind energy is so popular. Mainly it will never run out. Because it is renewable, there is enough of it to produce electricity and other work. It is also clean because the wind farms do not release chemicals and environmentally polluting agents when they produce electricity. Additionally it is a safe energy source for all living things on the planet. Economically wind energy sustains many jobs worldwide, and even though wind farms need large areas of wide open land, the turbines itself occupy only about 2% to 3% of the land. That means that this land can also be used for other development. The other great thing about wind energy is that it is able to recover the energy it used to create electricity within a few months. Even though there are many advantages of wind energy, there are a few negative impacts on the environment by wind turbines. There have been a few oil leaks, and fires. Although they are not many, the risk of having more such accidents is present. Many people also feel that the presence of these huge wind turbines ruins the scenic beauty of the countryside and landscape, and that they are quite noisy. The future of wind energy looks promising. Experts believe that because of its zero production costs, the support from many governments around the world, and the increasing disadvantages of using fossil fuels, by the year 2050, wind energy would be supplying energy to more than one third of the world’s population.