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The Energy Portal
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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.

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The Sun 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 available energy 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.

Selected article

Four-stroke internal combustion engine
The internal combustion engine is widely used to power a great variety of vehicles and other devices. It is an engine in which the burning of a fuel occurs in a confined space called a combustion chamber. This exothermic reaction of a fuel with an oxidizer creates gases of high temperature and pressure, which are permitted to expand.

The defining feature of an internal combustion engine is that useful work is performed by the expanding hot gases acting directly to cause movement, for example by acting on pistons, rotors, or even by pressing on and moving the entire engine itself.

Internal combustion engines are most commonly used for mobile propulsion systems, where their high power-to-weight ratios, together with excellent fuel energy-density, are advantageous. They have appeared in almost all automobiles, motorbikes, many boats, and in a wide variety of aircraft and locomotives. Where very high power is required, such as jet aircraft, helicopters and large ships, they appear mostly in the form of gas turbines. They are also used for electric generators and by industry.

The most common fuels in use today are hydrocarbons derived from petroleum including diesel, gasoline and liquified petroleum gas. Most internal combustion engines designed for gasoline can run on natural gas or liquified petroleum gases without modifications except for the fuel delivery components. Liquid and gaseous biofuels, including ethanol and biodiesel can also be used, and trials of hydrogen fuel have been in progress for some years. Read more...

Selected image

Coal power plant Datteln 2 Crop1.png

Photo credit: From an image by Arnold Paul
Coal-fired power stations transform chemical energy into 36%-48% electricity and 52%-64% waste heat.

Did you know?

  • Positive lightning bolts are typically six to ten times more powerful than normal lightning — and aircraft are not designed to withstand them?
  • Dark energy is a hypothetical form of energy which permeates all of space?

Selected biography

James Watt (19 January 1736 – 19 August 1819) was a Scottish inventor and engineer. His improvements to the steam engine, which had hardly changed for fifty years, produced a source of power that transformed the world of work, and was the key innovation that brought forth the Industrial Revolution.

In recognition of Watt's achievements, the SI unit of power, the watt, is named after him.

James Watt was born on 19th of January, 1736 in Greenock, a seaport on the Firth of Clyde. His father was a shipwright, shipowner and contractor, while his mother, Agnes Muirhead, came from a distinguished family and was well-educated. Both were Presbyterians and strong Covenanters. Watt attended school irregularly and instead was mostly schooled at home by his mother.

After studying instrument-making for a year in London, the University of Glasgow offered him the opportunity to set up a small workshop within the university. It was established in 1757. After four years, Watt began to experiment with steam, finally producing a working model steam engine in 1765. Strapped for resources to develop a full-scale engine, Watt was forced to take up employment as a surveyor for eight years. Finally, in 1776, the first engines were installed and working in commercial enterprises.

After further improvements, Watt and foundry owner Matthew Boulton established Boulton and Watt in 1794 to exclusively manufacture steam engines. By 1824 it had produced 1,164 steam engines having a total nominal horsepower of about 26,000. Read more...

Energy news

Wikinews on energy
Renewable energy news


  • "Without radical international measures to reduce carbon emissions within the next 10 to 15 years, there is compelling evidence to suggest we might lose the chance to control temperature rises. Failure to act will make an increase of between 2 and 5 degrees [3.6 - 9°F] in average temperatures almost inevitable." – Tony Blair, 2006
  • "The question is not whether climate change is happening or not, but whether, in the face of this emergency, we ourselves can change fast enough." – Kofi Annan, 2006
  • "I promise you a day will come when our children and grandchildren will look back and they will ask one of two questions. Either they will ask, 'What in God's name were they doing? Didn't they see the evidence?' Or, they may look back and say 'How did they find the uncommon moral courage to rise above politics and redeem the promise of American democracy?'" – Al Gore, 2007, on global warming.

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