Science, Maths & Technology

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# Energy reaching the Earth

How much of the Sun’s energy reaches us?

• The average living-room floor area in the UK is around 17 m2. Take a guess as to how many 40 W incandescent light bulbs would provide the same energy in an average living room as the energy that reaches the Earth from the Sun:                 Around 150?                 Around 1500?                 Around 15 000?

• The answer is 146 light bulbs. This might seem surprisingly small, considering the huge output of the Sun, but the Earth intercepts only a tiny fraction of this as it orbits.

The Earth is so far from the Sun, and is so small, that the rate at which this energy falls on the planet is only 343 Watts per metre squared (Wm2). It is this energy that you will be aiming to reduce in your geoengineering design.