The Energy Portal
Welcome to Wikipedia's Energy portal, your gateway to energy. This portal is aimed at giving you access to all energy related topics in all of its forms.
is the source of energy for most of life on Earth. As a star, the Sun is heated to high temperatures by the conversion of nuclear binding energy
due to the fusion of hydrogen in its core. This energy is ultimately transferred
(released) into space mainly in the form of radiant (light) energy
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object. Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.
Mass and energy are closely related. Due to mass–energy equivalence, any object that has mass when stationary (called rest mass) also has an equivalent amount of energy whose form is called rest energy, and any additional energy (of any form) acquired by the object above that rest energy will increase the object's total mass just as it increases its total energy. For example, after heating an object, its increase in energy could be measured as a small increase in mass, with a sensitive enough scale.
Living organisms require exergy to stay alive, such as the energy humans get from food. Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy. The processes of Earth's climate and ecosystem are driven by the radiant energy Earth receives from the sun and the geothermal energy contained within the earth.
In 2004, the worldwide energy consumption
of the human race was on average 15 terawatts (TW; 1 TW = 1 x 1012 W
) with 86.5% from burning fossil fuels
. This is equivalent to 471,000 P
J (1 PJ = 1 x 1015 J
) per year. There is at least 10% uncertainty in these figures due to national variations in tracking consumption, and due to variations in energy content between particular barrels of oil or tons of coal.
The remaining worldwide energy resources are large, with the remaining fossil fuels totaling an estimated 0.4 YJ (1 YJ = 1024 J) and the available nuclear fuel such as uranium exceeding 2.5 YJ (1 YJ = 1024 J). Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total energy usage), or 3.8 YJ/yr, dwarfing all non-renewable resources.
Despite the abundance of fossil fuels there are a number of pressures that may move the world’s energy consumption to alternative energy sources. These include political considerations over energy security and potential pressure from energy superpowers, environmental concerns related to global warming and sustainability, and economic pressure resulting from energy price rises, carbon emissions trading and green taxation.
This move is already starting to happen in some countries, notably as a result of the Kyoto Protocol, and further steps in this direction are proposed. For example, the European Commission has proposed that the energy policy of the European Union should set a binding target of increasing the maximum level of renewable energy in the EU’s overall mix from less than 7% today to 20% by 2020. Read more...
Did you know?
William Thomson, 1st Baron Kelvin
, (26 June 1824 – 17 December 1907), widely known for developing the Kelvin
scale of absolute temperature measurement, was a mathematical physicist
, and outstanding leader in the physical sciences
of the 19th century
. He did important work in the mathematical analysis
, and did much to unify the emerging discipline of physics
in its modern form.
Born in Ireland, Thomson studied at the University of Glasgow, Scotland. On graduating, he became a mathematics teacher at the Royal Belfast Academical Institution. During his life Thomson published more than 600 scientific papers and filed over 70 patents.
As early as 1845 Thomson pointed out that the experimental results of William Snow Harris were in accordance with the laws of Coulomb. Over the period 1855 to 1867, Thomson collaborated with Peter Guthrie Tait the Treatise on Natural Philosophy that unified the various branches of physical science under the common principle of energy. His inventions included the current balance for the precise specification of the ampere, the standard unit of electric current.
In 1893, Thomson headed an international commission to decide on the design of the Niagara Falls power station. Despite his previous belief in the superiority of direct current electric power transmission, he agreed to use alternating current after seeing a Westinghouse demonstration at the Chicago World's Fair. Read more...
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