The total solar energy available to the earth is approximately 3850 ZJ (zettajoules) per year. Oceans absorb approximately 285 ZJ of solar energy per year.It's those last two numbers that are the most revealing. All the life on Earth, after about 3 billion years of evolution, blanketing nearly the whole land surface and much of the ocean, can capture 0.05% of the sunlight that hits the planet. So how much do you think humans can capture? Doesn't that suggest that referring to total solar energy hitting the Earth is meaningless? What matters is not how much energy reaches the planet, but how much can be usefully converted. All of life, all over the planet, can only capture about 4 times more solar energy than the energy humans use in the form of petroleum. That gives you an idea of how much hardware we'd need to keep up the current rate without oil. We already redirect for our needs about 40% of current biomass produced on the planet, according to some figures. So it's going to be tough to increase that amount without even more seriously disrupting ecosystem function.
Winds can theoretically supply 6 ZJ of energy per year. Biomass captures approximately 1.8 ZJ of solar energy per year.
Worldwide energy consumption was 0.471 ZJ in 2004.
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