Cool link:
http://en.wikipedia.org/wiki/Earth%27s_energy_budgetIncoming energy
The total flux of energy entering the Earth's atmosphere is estimated at 174 petawatts. This flux consists of:
* solar radiation (99.97%, or nearly 174 petawatts; or about 340 W m−2)
o This is equal to the product of the solar constant, about 1,366 watts per square metre, and the area of the Earth's disc as seen from the Sun, about 1.28 × 1014 square metres, averaged over the Earth's surface, which is four times larger. The solar flux averaged over just the sunlit half of the Earth's surface is about 680 W m−2
o This is the incident energy. The energy actually absorbed by the earth is lower by a factor of (1 minus albedo); this is discussed in the next section.
o Note that the solar constant varies (by approximately 0.1% over a solar cycle); and is not known absolutely to within better than about one watt per square metre. Hence the geothermal, tidal, and waste heat contributions are less than the uncertainty in the solar power.
* geothermal energy (0.025%; or about 44[2] to 47[3] terawatts; or about 0.08 W m−2)
o This is produced by stored heat and heat produced by radioactive decay leaking out of the Earth's interior.
* tidal energy (0.002%, or about 3 terawatts; or about 0.0059 W m−2)
o This is produced by the interaction of the Earth's mass with the gravitational fields of other bodies such as the Moon and Sun.
* waste heat from fossil fuel consumption (about 0.007%, or about 13 terawatts; or about 0.025 W m−2)[4] The total energy used by commercial energy sources from 1880 to 2000 (including fossil fuels and nuclear) is calculated to be 17.3x1021Joules.[5]