Solar Energy

Some big picture numbers...

• Power output of the sun: ≈ 3.6 × 10²⁶ Watts [1]


• Proportion of solar energy falling on earth: 1 / (2.21 × 10⁹) [2]


• Solar energy falling on earth: 1.6 × 10¹⁷ Watts


• Earth surface area: 5.1 × 10¹⁴ m²


• Average energy per unit surface area: 313 Watts / m²

Notes

• A proportion of that energy is reflected or absorbed into the atmosphere before it reaches ground level (Earth overall albedo is about 30% [3]).


• Also not sure how much of that energy is realistically useable, e.g. what the spread of energy is over the EM spectrum and how that fits with our ability to use the energy (e.g. what is the EM utilisation profile of solar techs?)


• 2008 world energy consumption rate: 15 terawatts (1.504 × 10¹³ Watts) [4], so about 1/10000th the solar energy hitting the earth.

References

[1] http://www.wolframalpha.com/input/?i=3.6%C3%9710^26+watts&lk=1

[2] Surface area of sphere with radius 1AU ≈ 2.81 × 10²³ m²
     Earth cross section area ≈ 1.27 × 10¹⁴ m²
     Earth cross section as proportion of 1AU sphere ≈ 1 / (2.21 × 10⁹)

[3] http://earthobservatory.nasa.gov/IOTD/view.php?id=5484

[4] http://en.wikipedia.org/wiki/World_energy_consumption

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