The correct answer is 179,000 km2.
Use the formula (area) = (power)/(flux): the answer is 1.38x107 MW divided by 77 MW/km2.
This is about the area of the state of Missouri (you may have come up with other choices).
Finally, suppose (as currently suggested by the U.N.) that world population stabilizes at about 9.2 billion late in the next century. Assume that we want to use solar power exclusively to provide everyone with the same standard of living enjoyed by Americans now. Recall than in 2003 the total power consumption by the U.S. was 3.29x106 MW. This was for a population of 291,000,000. Find the total world energy needs, at this same rate per person, for a population of 9.2 billion. Then find the collecting area now required.
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Last modified 11 January 2005.
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