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 ...

Rebates to cut price of $60 LED bulb

(AP) -- How much would you pay for an amazing, state-of-the-art light bulb? Shoppers will be asking themselves that very question at Home Depot and other outlets starting Sunday - Earth Day - when the bulb that won a $10 ...

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 ...

Water-shedding surfaces can be made to last

Steam condensation is key to the worldwide production of electricity and clean water: It is part of the power cycle that drives 85 percent of all electricity-generating plants and about half of all desalination plants globally, ...

Smart technology can help conserve energy use at home

Our homes are getting smarter. Smart technology that automates our homes' devices is becoming mainstream, making it convenient for us to rein in our energy use and cut our energy bills.

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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