Comparison with other methods of power generation

Hydroelectricity eliminates the flue gas emissions from fossil fuel combustion, including pollutants such as sulfur dioxide, nitric oxide, carbon monoxide, dust, and mercury in the coal. Hydroelectricity also avoids the hazards of coal mining and the indirect health effects of coal emissions. Compared to nuclear power, hydroelectricity generates no nuclear waste, has none of the dangers associated with uranium mining, nor nuclear leaks. Unlike uranium, hydroelectricity is also a renewable energy source.

Compared to wind farms, hydroelectricity power plants have a more predictable load factor. If the project has a storage reservoir, it can be dispatched to generate power when needed. Hydroelectric plants can be easily regulated to follow variations in power demand.

Unlike fossil-fuel combustion turbines, construction of a hydroelectric plant requires a long lead-time for site studies, hydrological studies, and environmental impact assessment. Hydrological data up to 50 years or more is usually required to determine the best sites and operating regimes for a large hydroelectric plant. Unlike plants operated by fuel, such as fossil or nuclear energy, the number of sites that can be economically developed for hydroelectric production is limited; in many areas the most cost effective sites have already been exploited. New hydro sites tend to be far from population centers and require extensive transmission lines. Hydroelectric generation depends on rainfall in the watershed, and may be significantly reduced in years of low rainfall or snowmelt. Long-term energy yield may be affected by climate change. Utilities that primarily use hydroelectric power may spend additional capital to build extra capacity to ensure sufficient power is available in low water years.

In parts of Canada (the provinces of British Columbia, Manitoba, Ontario, Quebec, Newfoundland and Labrador) hydroelectricity is used so extensively that the word "hydro" is often used to refer to any electricity delivered by a power utility. The government-run power utilities in these provinces are called BC Hydro, Manitoba Hydro, Hydro One (formerly "Ontario Hydro"), Hydro-Québec and Newfoundland and Labrador Hydro respectively. Hydro-Québec is the world's largest hydroelectric generating company, with a total installed capacity (2007) of 35,647 MW.

 

Isaac Newton

Isaac Newton (1643-1727) - English mathematician, engineer, astronomer and physicist, founder of classical mechanics, the term (1672) and President (since 1703) Royal Society of London. One of the founders of modern physics, formulated the basic laws of mechanics and was the actual creator of a unified program of physical descriptions of all physical phenomena on the basis of mechanics, discovered the law of universal gravitation, explained the motion of the planets around the sun and the moon around the earth and tides in the oceans, laid the foundations of continuum mechanics environments, acoustics and physical optics. Fundamental works "Mathematical Principles of Natural Philosophy" (1687) and "Optics" (1704). Newton worked out (regardless of Gottfried Leibniz) the differential and integral calculus. He opened the dispersion of light, chromatic aberration, investigated the interference and diffraction, developed the corpuscular theory of light, he hypothesized that combined corpuscular and wave representations. I built a reflecting telescope. Isaac Newton formulated the basic laws of classical mechanics. He discovered the law of universal gravitation, gave the theory of motion of celestial bodies, creating the foundations of celestial mechanics. Space and time are considered absolute. Newton's work far ahead of the overall scientific level of his time, with unclear contemporaries. He was director of the Mint, established coinage in England.

Early years

Isaac Newton was born on January 4, 1643, at Woolsthorpe near Grantema, Lincolnshire, in a small village in the family of a small farmer, who died three months before his son's birth. The baby was premature, there is a legend that it was so small that it was placed in a sheepskin mitt lying on the bench, from where he once fell and hit his head heavily on the floor. When the child was three years old, his mother remarried and left, leaving him in the care of her grandmother. Newton grew up sickly and unsocial, prone to reverie. He was attracted by poetry and painting, he is away from his peers, was making kites, he invented a windmill, a water clock, pedal cart. It was difficult for the beginning of school life of Newton. He studied bad boy was weak, and once classmates beat him until he lost consciousness. Transferring such a humiliating situation was touchy for Isaac Newton is unbearable, and there was one: to stand out success in their studies. Hard work, he has ensured that won first place in the class. Interest in the technology has forced Newton to reflect on the phenomens of nature, he was deeply involved and mathematics. This later wrote Jean Baptiste Biot: "One of his uncles, finding him once under the hedge with a book in his hands, lost in deep thought, he took the book, and found that he was busy solving mathematical problems. Struck by such a serious and active direction as a young man, he persuaded his mother not to oppose further request and send his son to continue the occupation. " After extensive training in 1660, Isaac Newton went to Cambridge as Subsizzfr'a (so-called poor students who had to serve the members of the college, which could not weigh Newton).

Getting creative. Optics

In six years, Isaac Newton had passed all college degree and prepared all his great discoveries further. In 1665 Newton became master of arts. In the same year, when the plague was raging in England, he decided to temporarily settle at Woolsthorpe. It was there that he began to actively engage in optics, searching for ways to eliminate chromatic aberration in the lens telescope led Newton to research what is now called the variance, t. E. Depending on the refractive index of the frequency. Many of the experiments conducted by them (and there are more than a thousand) have become classics and are repeated today in schools and institutions. The leitmotif of all the research was to understand the physical nature of light. First, Newton was inclined to think that light - is the wave of all-pervading ether, but he later abandoned the idea, thinking that the resistance of the air would have a noticeable slow down the movement of the heavenly bodies. These arguments have led Newton to the notion that light - a stream of special particles, corpuscles emitted from a source and moving in a straight line until they meet an obstacle. The corpuscular model explains not only the straightness of light, but also the law of reflection (elastic reflection), and - though not without additional assumptions - and the law of refraction. This assumption was that light corpuscles, flying to the surface of the water, for example, should be attracted by it and therefore be accelerated. According to this theory the speed of light in water should be greater than in air (which came into conflict with the later experimental data).

The laws of mechanics

The formation of the corpuscular theory of light explicitly influenced, at that time already, mainly to complete the work which was to be the main result of the great works of Newton - the creation of a unified, based on the laws of mechanics, he formulated the physical world. The basis of this idea of ​​painting lay a material point - physically infinitesimal particles of matter and the laws governing their motion. It is a clear statement of the law and gave the mechanics of Isaac Newton fullness and completeness. The first of these laws was, in fact, the definition of inertial reference systems: in such systems have not experienced any material impact points move uniformly in a straight line. The second law of mechanics plays a central role. It states that the change in the amount of movement (the product of mass and velocity) per unit time is equal to the force acting on a material point. The weight of each of these points is a constant size. In general, all these points are not "wear out" in the words of Newton, each of them is eternal, t. E. Can neither arise nor destroyed. Material terms interact, and quantitative measure of the impact on each of them and is a force. The task of finding out what these forces is the root problem of mechanics. Finally, the third law - the law of "equality of action and reaction" to explain why the total momentum of a body does not experience external influences, remains the same, no matter how interacted its component parts.

Гидроэлектроэнергия

Гидроэлектроэнергия - электричество созданное гидроэнергетикой, то есть, энергия произведённая в результате падения или течения воды под действием сил гравитации. Это наиболее широко использованная форма возобновляемой энергии. Однажды построенный гидроэлектроэнергетический комплекс не создает никаких отходов, а также обладает более низким уровнем производства парникового газа – оксида углерода, чем при сжигании органического топлива для получения энергии на заводах. Во всем мире, гидроэлектроэнергетика произвела около 715,000 мегаватт электроэнергии в 2005. Это составило приблизительно 19% всемирного электричества (в сравнении с 16% в 2003), и составляет более 63% электроэнергии из возобновляемых источников.

Производство электроэнергии

Большая часть гидроэлектроэнергии создается за счет потенциальной энергии запруженной воды, которая приводит в действие водяную турбину и генератор. В этом случае энергия извлеченная из воды зависит от объема и разницы в высоте между источником и водостоком. Это различие высоты называется напор. Сумма потенциальной энергии воды пропорциональна напору. Чтобы получить очень высокий напор, вода для гидравлической турбины может быть пущена через большую трубу названую шлюзом.

Гидроаккумулирующие электростанции производят электроэнергию во время пиков нагрузки, перемещая воду между резервуарами с различными высотами. Во время низкого электропотребления, избыток энергии используется, чтобы закачать воду в более высокий резервуар. Когда появляется максимум потребления, вода снова спускается в более низкий резервуар через турбину. Гидроаккумулирующие схемы в настоящее время снабжают только важные коммерческие крупномасштабные энергосети сохраняя суточную нагрузку генерирующей системы. Гидроэлектрические заводы без возможности сохранять воду называются русловыми ГЭС. Приливная электростанция использует ежедневное повышение и падение воды из-за приливов и отливов; такие источники - очень предсказуемые, и если условия разрешают конструкцию водохранилищ, то они также могут быть использованы, чтобы генерировать мощность в течение максимумов потребления.

Менее распространенные типы гидро схем используют кинетическую энергию воды или незапруженные источники как например, колесо мельницы.

Существует простая формула, чтобы определять количество электроэнергии произведенное на гидростанции: P = hrgk, где P - мощность в киловаттах, h - напор в метрах, r - расход воды в кубических метрах в секунду, g - ускорение свободного падения 9,8 м/с², и k - коэффициент полезного действия, колеблющийся от 0 до 1. Эффективность часто более высокая с большими и более современными турбинами.

Годовое производство электроэнергии зависит от количества поступающей воды. В некоторых системах скорость течения воды может изменяться с коэффициентом 10:1 в течение года.