Posted by
grad_1986 on Monday, March 14, 2011 2:33:05 AM
I went online today to find out how much energy can be collected from the Sun using solar panels. One site made me laugh as it posted that the sun produces over 3.8 x 10^23 kw-hr of energy. I almost fell of my seat from laughing. This kind of junk science is used all over the world to push for "green energy" and it needs to be confronted.
1) We do not receive all the sun's energy. The energy is spread of an area = 4*pi*r^2 (in our case r = 93 million miles). Of that surface area we only collect 3.7x10^6 sq-miles in the United States. . Doing the math, we only receive 9.24x10-10 of the energy the sun produces leaving us with 12.9x10^12 kw/hr. Still a large amount.. but lets continue
2) We only receive light for about 8 hours of the day and for much of the day the light entering the earth is not perpendicular to the earths surface but instead comes in a an angle. On average much of the light coming in is only usable from about 9am-3pm (about 6 hours). This reduces our "average energy by about 25%. Therefore we are down to 3.23x10^11 kw/hr
3) We receive only about 10% of the energy the sun produces. The rest is either absorbed by the magnetosphere, the ozone layer or our atmosphere (without that we would all either freeze to death or fry like bacon). So that reduces our energy down to 3.23x10^10 kw-hr.
4) Not all the energy sent can be utilized for electrical conversion. Of the spectrum of light only a 10% can be used). Thereby cutting the energy down to 3.23x10^9
5) Now come the hard part... how much do we a lot for electrical energy development and how much for other uses like GROWING FOOD! This is the part that many green advocates fail to recognize. Every ray of light used by solar panels is a ray of light taken away for other uses like growing food or trees. Many scientists have speculated that we could only probably be able to spare about 1% of our use-able land area for this purpose. Germany saw what happened when the government made solar-farms so "economical" that corn, wheat and barley farmers stopped their farming and created a food shortage. So if we take their recommendation of 1% we are down to 3.23x10^7 kw/hr of energy.
So how much energy DO we need every day in the United States? Last census showed that we need about 5x10^8 kw/hr. That means that solar energy can only produce about 5% of our nations energy.... MAX! You are not going to get the sun to increase its energy output (unless of course it decides to go Super-Nova on us..but that is a different problem).