Portal:Energy
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Introduction
In physics, energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. 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 unit of measurement for energy in the International System of Units (SI) is the joule (J).
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, and the internal energy contained within a thermodynamic system. All living organisms constantly take in and release energy.
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.
Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy. The Earth's climate and ecosystems processes are driven by the energy the planet receives from the Sun (although a small amount is also contributed by geothermal energy). (Full article...)
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To avoid dangerous climate change, the energy policy of the European Union has set a 2°C [3.6°F] limit to the temperature rise, compared to pre-industrial levels. Of this, 0.8°C has already taken place and another 0.5°C is already committed. The 2°C rise is associated with a carbon dioxide concentration of 400–500 ppm by volume; as of January 2007 it was 383 ppm by volume, and rising at 2 ppm annually. Unless significant action is taken soon the 2°C limit is likely to be exceeded.
Strategies for moving to a low-carbon economy include development of new technologies, particularly renewable energy; electric and hybrid vehicles; fuel cells; public transportion; zero-energy buildings; Zero-Net-Energy USA Federal Buildings; energy conservation; carbon taxes; enhancing natural carbon dioxide sinks; population control; and carbon capture and storage. Environmental groups also encourage individual-lifestyle and political action, as well as action by business.
The Kyoto Protocol, covering more than 160 countries and over 55% of global emissions provides an international mitigation framework. The United States, the world's largest greenhouse gas emitter; and Kazakhstan have refused to ratify the treaty. China and India, two other large emitters, have ratified the treaty but are exempt from cutting emissions. International talks on a successor to the treaty, which ends in 2012, have begun.
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Photo credit: Johnson Space Center/NASA
Tropical cyclones feed on the heat released when moist air rises and the water vapor condenses.
Did you know?
- If atmospheric greenhouse gas concentrations can be stabilized at 450 ppm, it is thought that there will be a 50% chance of avoiding dangerous climate change?
- The Itaipu hydroelectric power plant is currently the second largest power plant in the world, supplying over 90% of Paraguay's electricity, and 25% of Brazil's?
- Libya's Sirte Basin—which in some places lies more than 47 metres below sea level—contains roughly 80% of the country's known crude oil reserves?
- Approximately 95% of the electricity consumed by a normal incandescent light bulb (example pictured) is emitted as heat, rather than as visible light?
- Saudi Aramco is the largest oil corporation in the world and the world's largest in terms of proven crude oil reserves and production?
- Newcastle, Australia, is the world's largest coal export port?
- Surplus income from oil production in Norway is invested by the Government Pension Fund, one of the World's largest funds with a value of around US$ 800 billion?
- Energy superpowers Russia and Venezuela have, respectively, the world's largest reserves of natural gas and petroleum?
Selected biography
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.
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Quotations
- "My administration is committed to a leadership role on the issue of climate change. We recognize our responsibility and will meet it - at home, in our hemisphere, and in the world." – George W. Bush, 2001
- "While the Kyoto Protocol is a crucial step forward, that step is far too small. And as we consider how to go further still, there remains a frightening lack of leadership." – Kofi Annan, 2006
- "It is going to be very difficult to keep temperature increases down to between 2 and 3 degrees centigrade [3.6 - 5.4°F]. We should work very hard to do that." – Nicholas Stern, 2006
- "Halting global warming requires urgent, unprecedented international cooperation, but the needed actions are feasible and have additional benefits for human health, agriculture and the environment." – James E. Hansen, 2004
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