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(Solar) Power to the Masses
D3 writes "This report on a solar power tower (pdf) looks extremely interesting. Maybe one day we can have international power lines where all the countries with lots of sunshine provide power to the rest of the world? How cool would that be?" The NY Times has a good article on solar power in Japan.
Solar insolation is about 1kW/m^2.. Well, except for the earths rotation. Assuming a non-tracking system, we have to divide by a factor of pi, so thats 300 W/m^2.. Well, except that the average efficiency of solar cells is under 15%, so thats 45W/m^2. Now, the average home has what? 2 people in it, and the per-capita electrical usage, averaged over the course of a year is 1kW. So, you need 2kW for that home, and only get 45W/m^2. So, you need 50 square meters of solar cell, correctly angled south. And this is the best case.
Now account for clouds and dirty cells. Unless you clean the cells every few days and pressure wash them biweekly, better increase the square meters of solar cells another 50%. So, thats 60-80 square meters of cell/house..
Now the next question. Where do you store all the energy you'll use at night? If you don't store it, where does it come from? Fancy burying a few ton flywheel in your backyard? How about aa closet filled with lead and sulpheric acid batteries? If you're going to use hydrogen to store it, better double or triple the square meters of solar cell for those inefficiencies.
The same problem applies to 'Solar 2'. You need about 1000 of them to equal the average energy of a nuclear power plant. And another 299000 to equal the mean energy used by the US. To replace all energy used in the US requires about a million Solar 2's.