If we covered 10% of the Earth with SOLAR CELLS would we create a 'Global Cooling'?
Question:
My aeronautical engineer Grandfather proposed that we might cause the opposite of 'Global Warming' by covering the Earth with solar cells as a means to get off a dependence of fossil fuels.
The notion stemmed from the logic that solar cells turn photons into electricity as opposed to heat. Currently, solar cells are anywhere from a max of 15-20% efficient, which means 80% is reflected off as heat/diffuse light (i think that's right - don't hate me if it's wrong- tis not my expertise). This means that some portion of the photons incident upon them will NOT be converted into heat. As electricity, some amount of photon-origin heat that was acting upon the earth is now unaccounted for in solar cells.
So, with this logic, if you remove that heat from the overall system, does it cause Global Cooling or would the net effect of the environmental impact be insignificant?
Answer:
Interesting question...
You're energy analysis is a fairly accurate assessment - 20% converted to electricity and 80% lost as heat.
As for the global cooling, I'm not too sure.
At present the excessive burning of fossil fuels has been accumulating in the atmosphere which is trapping heat in and causing the global warming. Even if we start using only solar and other green energy sources and stop using combustion engines, fuel burning power plants, wood burning stoves, etc (which is difficult to imagine) it is going to take a long time to clean up the current "load." And, besides a single naturally occurring phenomena (like volcanic eruptions) could possibly double the current global warming gas concentrations from one single event.
However, if atmospheric gases and debris becomes to thick global warming could turn to global cooling because very little of the sun energy makes it through this layer and down to the earths surface.
Does that mean that there is no hope... maybe. It all depends on what happens over the next few years. If China goes down the US road to economic development, as other nations have started down, then we will see dramatic climate changes occurring within our lifetime. However, if "we" all go green, we may decrease or sustain the current rate of global climatic changes... either way, the planet will eventually exceed it's natural limitations.
If you're interested in natural sustain ability I recommend you read G. Hardins "Tragedy of the Commons" (http://dieoff.com/page95.htm). It's a good read and the basic ideas apply to all natural systems ... real life examples include: the mule deer population changes in Arizona, early 1900's; Easter Island; "global warming(?)"...
Addressing your question without the consequences and feasibility of such an attempt is not practical.
As far as feasibility goes, we do not have that much solar PV cells to cover the earth.
With current technology used for solar PV cells, attempting to manufacture that volume would create more harmful greenhouse gases and toxic pollution than any cooling benefit gained.
However, we can harness solar energy like plants do, in a far more efficient way.
All it needs, is genuine funding and drive to reverse engineer billions of years of evolution invested in plants.
Your imagination may become true in future.! As costs of solar products decrease, solar energy is replacing electricity/fossil in many application like lighting, cooking and heating. As per your theory Glob is protected as well as energy is produced. Please visit http://altenergy.in/for more information on solar power.
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