The limits of ocean heavyweights: Prey curb whales' gigantic size

At 100 feet long and weighing more than 100 tons, blue whales are the largest creatures to have evolved on the planet. Other whales, like killer whales, are larger than most terrestrial animals but pale in comparison to the ...

Plants do sums to get through the night, researchers show

(Phys.org) —New research shows that to prevent starvation at night, plants perform accurate arithmetic division. The calculation allows them to use up their starch reserves at a constant rate so that they run out almost ...

IKEA commits to energy independence by 2020

(Phys.org)—Furniture giant IKEA has announced plans to produce as much energy as it consumes by the year 2020. To achieve that goal, the company will install solar panels on all its stores and warehouses, and invest in ...

Birds do it—Passenger planes will fly in formation too

(Phys.org)—Toulouse-based Airbus, a world-leading aircraft manufacturer, has issued its "vision" of what truly smart flying—smart, that is, as in sustainable rather than smart as in sensor-packed—will be like in 2050. ...

Snake-alike Titanoboa robot is beyond eek (w/ video)

(PhysOrg.com) -- Many 40-something surfers become six year olds when seeing spiders, snakes, and insects in machine form. They either think the machines are scary but funny or at the least entertaining. A group of artists ...

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World energy resources and consumption

In 2005, total worldwide energy consumption was 500 Exajoules (= 5 x 1020 J) with 80-90% derived from the combustion of fossil fuels. This is equivalent to an average energy consumption rate of 16 TW (= 1.585 x 1013 W). Not all of the world's economies track their energy consumption with the same rigor, and the exact energy content of a barrel of oil or a ton of coal will vary with quality.

Most of the world's energy resources are from the sun's rays hitting earth - some of that energy has been preserved as fossil energy, some is directly or indirectly usable e.g. via wind, hydro or wave power. The term solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere, in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just visible light. It is measured by satellite to be roughly 1366 watts per square meter, though it fluctuates by about 6.9% during a year - from 1412 W/m2 in early January to 1321 W/m2 in early July, due to the Earth's varying distance from the sun, and by a few parts per thousand from day to day. For the whole Earth, with a cross section of 127,400,000 km², the total energy rate is 1.740×1017 W, plus or minus 3.5%. This 174 PW is the total rate of solar energy received by the planet; about half, 89 PW, reaches the Earth's surface.

The estimates of remaining worldwide energy resources vary, with the remaining fossil fuels totaling an estimated 0.4 YJ (1 YJ = 1024J) and the available nuclear fuel such as uranium exceeding 2.5 YJ. Fossil fuels range from 0.6-3 YJ if estimates of reserves of methane clathrates are accurate and become technically extractable. Mostly thanks to the Sun, the world also has a renewable usable energy flux that exceeds 120 PW (8,000 times 2004 total usage), or 3.8 YJ/yr, dwarfing all non-renewable resources.

This text uses material from Wikipedia, licensed under CC BY-SA