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When you follow only some of these easy methods, you will notice in the end of the year that you saved tones of energy! | When you follow only some of these easy methods, you will notice in the end of the year that you saved tones of energy! | ||
== Future of Energy == | |||
== See also == | == See also == | ||
Revision as of 14:02, 21 October 2014
History
The word energy derives from the Ancient Greek: ἐνέργεια energeia “activity, operation”, which possibly appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness and pleasure.
In the late 17th century, Gottfried Leibniz proposed the idea of the Latin: vis viva, or living force, which defined as the product of the mass of an object and its velocity squared; he believed that total vis viva was conserved. To account for slowing due to friction, Leibniz theorized that thermal energy consisted of the random motion of the constituent parts of matter, a view shared by Isaac Newton, although it would be more than a century until this was generally accepted. The modern analog of this property, kinetic energy, differs from vis via only by a factor of two.
In 1807, Thomas Young was possibly the first to use the term "energy" instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described "kinetic energy" in 1829 in its modern sense, and in 1853, William Rankine coined the term "potential energy". The law of conservation of energy, was also first postulated in the early 19th century, and applies to any isolated system. It was argued for some years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity, such as momentum. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat.
These developments led to the theory of conservation of energy, formalized largely by William Thomson (Lord Kelvin) as the field of thermodynamics. Thermodynamics aided the rapid development of explanations of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, and Walther Nernst. It also led to a mathematical formulation of the concept of entropy by Clausius and to the introduction of laws of radiant energy by Jožef Stefan. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time. Thus, since 1918, theorists have understood that the law of conservation of energy is the direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time.
Measurement and units
Energy, like mass, is a scalar physical quantity. The joule is the International System of Units (SI) unit of measurement for energy. It is a derived unit of energy, work, or amount of heat. It is equal to the energy expended (or work done) in applying a force of one newton through a distance of one metre. However energy is also expressed in many other units such as ergs, calories, British Thermal Units, kilowatt-hours and kilocalories for instance. There is always a conversion factor for these to the SI unit; for instance; one kWh is equivalent to 3.6 million joules.
The SI unit of power (energy per unit time) is the watt, which is simply a joule per second. Thus, a joule is a watt-second, so 3600 joules equal a watt-hour. The CGS energy unit is the erg, and the imperial and US customary unit is the foot pound. Other energy units such as the electron volt, food calorie or thermodynamic kcal (based on the temperature change of water in a heating process), and BTU are used in specific areas of science and commerce and have unit conversion factors relating them to the joule.
Because energy is defined as the ability to do work on objects, there is no absolute measure of energy. Only the transition of a system from one state into another can be defined and thus energy is measured in relative terms. The choice of a baseline or zero point is often arbitrary and can be made in whatever way is most convenient for a problem. For example in the case of measuring the energy deposited by X-rays as shown in the accompanying diagram, conventionally the technique most often employed is calorimetry. This is a thermodynamic technique that relies on the measurement of temperature using a thermometer or of intensity of radiation using a bolometer.
Energy density is a term used for the amount of useful energy stored in a given system or region of space per unit volume. For fuels, the energy per unit volume is sometimes a useful parameter. In a few applications, comparing, for example, the effectiveness of hydrogen fuel to gasoline it turns out that hydrogen has a higher specific energy than does gasoline, but, even in liquid form, a much lower energy density.
Definition
Energy is the power that is needed to do any types of work. The more energy there is, the more work you can do or the longer you can work on the same work. Energy can be won by natural sources and be created artificially.
Forms of energy
Energy is key to modern society, and is provided through:
- Fossil fuels: a storable form of energy which cause pollution and climate change
- Renewable energy from nature, namely solar, wind, geothermal, wave and tidal power. These are typically more expensive up front, but far more sustainable, cleaner and lower risk to the environment. Costs vary widely, and many specific technologies are under development.
- Biofuels: a storable form of energy which is either emissionless or close to emissionless
- Nuclear energy, which is a storable, emisionless form of energy, but carries risks (depending on the form of nuclear energy -ie through nuclear fission or nuclear fusion-).
- Human power - e.g. cycling for transport, which has benefits for health but which is a large burden if used for all required energy.
- Animal power - (see the pages in Category:Animal power). This is still used in developing countries, but relatively expensive in terms of feed used and time required for care.
For more specific information about energy, navigate the energy category or portal.
Problems with centralized power generation
"It is the experience of most developing countries that energy produced through centralized thermal, hydroelectric and nuclear power stations rarely flows to rural areas where the bulk of the population lives. A typical distribution for such centralized power production is about 80% for urban industry (based on energy intensive Western technology), about 10% for urban domestic consumption, and only about 10% for rural areas." - CERES: The FAO Review on Development, March-April 1976
Smart home
Smart home is a system to control the power consumption in everyone's household via funk. This system is provided by RWE(Rheinisch-Westfälisches Elektrizitätswerk AG)
Smart Grid
Natural energy sources
The use of alternative natural sources of energy is attractive because of the uncertain price and limited availability of oil, the pollution that is associated with the burning of fossil fuels, the tremendous experiences and dangers of nuclear power, and a variety of other reasons. In developing countries the first reason is of particular importance because their industrial development, coming at a time of low cost plentiful oil supplies, has resulted in greater reliance on this single source of energy than is true in the developed countries, despite the fact that the latter use tremendously larger quantities. For industrialized countries such as the United
States, practical and economically competitive alternative energy systems already exist that could replace the entire nuclear power contribution to U.S. energy supplies. (Note: Wood space heating stoves [selling 1-2 million units a year] surpassed nuclear power in total contribution to U.S. energy supplies in 1980!)
For village level applications, there are many promising existing technologies. The five sections which follow explore of these in more depth: sun, wind, water, wood and biogas. These technologies are small-scale and necessarily decentralized . This, rather than any other technical inferiority, is the primary. reason earlier forms of these technologies were eventually passed over in the industrialized countries. While these systems cannot very effectively be used for the power needs of large industry, they can be well suited to the needs of villages and small communities. They can be low in cost relatively simple in construction and maintenance, made of materials available in villages and small towns, and non-polluting.
With each price increase in the worlds diminishing oil supply, renewable energy sources are made more attractive. The decentralized supply of these renewable energy sources - wind power, solar energy, water power and biofuels - matches the decentralized settlements of the rural South. Planners and program administrators are increasingly convinced that these technologies have a major role in the energy supplies of rural communities.
Save energy
Energy is a precious resource. If we can safe energy, we will reduce the CO2 ejection, safe money and rescue our earth. There are some easy steps to decrease the energy consumption at home.
Efficiency - Pay attention when you buy new electronic devices like freezer or dishwasher. All these devices have efficiency score from F to A++++. It will be worth after a short time.
Switch off - If you go to bed, switch off all devices instead of set it to stand by.
Use caps - Cooking is a nice hobby. But don't forget to use a cap on the pots. Otherwise, 30% of the energy is lost.
Freezer placement - Place your Freezer where its cold anyways, because of that he hasn't to cool so much.
Washing - Wash at 40 degree and fill the washing machine complete. Don't use a dryer, your laundry likes fresh air!
Dishwasher - The same principle like the washing. Fill it complete!
Windows - Don't tilt the windows for hours. Better open them complete for a few minutes. That will reduce the energy for heating extreme!
Room temperature - If you reduce the room temperature only by some degrees, it will reduce the energy up to 10 percent!
Waste - Separate the waste. That will not save money, but you can save 1 kilo C02 for 1 kilo old paper!
When you follow only some of these easy methods, you will notice in the end of the year that you saved tones of energy!