US public views on climate and energy

Majorities of Americans say the federal government is doing too little for key aspects of the environment. And most believe the U.S. should focus on development of alternative sources of energy over expansion of fossil fuels, ...

Estimating the environmental impact of Bitcoin mining

As an alternative to government-issued money, the cryptocurrency Bitcoin offers relative anonymity, no sales tax and freedom from bank and government interference. But some people argue that these benefits have an enormous ...

Four ways to curb light pollution, save bugs

Artificial light at night negatively impacts thousands of species: beetles, moths, wasps and other insects that have evolved to use light levels as cues for courtship, foraging and navigation.

Can science break its plastic addiction?

Lucy Gilliam has an infectious passion for environmental action. Today, she works in Brussels on environmental transport policy. But in the early 2000s, she was a molecular microbiologist in Hertfordshire. Like many in her ...

3-D-printed plastics with high performance electrical circuits

Rutgers engineers have embedded high performance electrical circuits inside 3-D-printed plastics, which could lead to smaller and versatile drones and better-performing small satellites, biomedical implants and smart structures.

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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