"green" energy questions.

[fancycat]

People often talk about renewable energy, or energy that wont run out as it is harvested or exploited. From a physics stand point this concept is very strange to me.

Let's imagine for example that you put a wind turbine on the side of an acceding rocket. The turbine will generate a lot of electricity from rushing through the air, however this electricity is harvested from the force of the rockets momentum and manifests in the form of extra drag.

With solar energy there is no question as it comes from the sun burning itself out over a long period of time and that energy is being produced whether or not we make use of it. However with wind turbines, wouldn't their be an inherent slow down of wind that impacts the turbines?

if energy cannot be created or destroyed then converting the kinetic energy of the wind to electricity might cause some kind of inherent effects.

Granted these effects would be much less than what is caused by a large square building. I am not trying to preach about save the world or anything, I am just generally curious about the physics of it. Is wind and weather slimier to solar in that that energy is being used regardless of our exploitation of it?

(side note)

I hope one day to have a form of green generator for the sake of saving on my power bill.. my word power companies are expletive!

also solar energy relies on using solar power to knock electrons from the solar cell? if this is the case wont a solar cell become depleted after a while, as the positive ions begin to outnumber the available uncharged atoms of the crystal structure?

Edited August 15, 2013 by fancycat

[drakesdoom]

In all reality wind turbines are harvesting solar energy that has already been converted into kinetic energy known as wind by the weather patterns of the earth which are established by the uneven heating of the air by the sun.

[Kimberly]

"Wind energy" is basically the use of kinetic energy. This kinetic energy is created by an input of thermal energy from the sun. Local variations in thermal energy cause wind. Windmills do "slow down" the wind, but rarely to any significant effect, and as long as the sun keeps shining, there will be more wind.

Imagine a water wheel powered by rain. The water evaporates through the sun, falls down and powers the wheel, then evaporates again, etc. You're making use of solar input, that's how you can obtain electricity without using anything up on Earth.

Do note that "green" is not the same thing as "clean" or renewable. Nuclear energy is clean, and you make a good case for calling it "green", but it's not renewable--we will eventually run out of fissile material.

Edited August 15, 2013 by Kimberly

[SargeRho]

Renewable Energy simply means energy sources that do not deplete as you harvest them for a very long time, or replenish themselves rapidly. All renewable sources ultimately come from the Sun, so as long as the Sun burns and remains cool enough (so for at least another billion years). Wind is generated by the Sun heating up the ground, causing air to convect, and Turbines tap into that constantly replenished source of energy. So really, renewable energies are not a form of perpetual movement. Just extremely long duration movement. It'll last longer than humanity probably will.

[Moon Goddess]

(side note)

I hope one day to have a form of green generator for the sake of saving on my power bill.. my word power companies are expletive!

also solar energy relies on using solar power to knock electrons from the solar cell? if this is the case wont a solar cell become depleted after a while, as the positive ions begin to outnumber the available uncharged atoms of the crystal structure?

I see no one has touched your side note I'll do my best here... Remember that an electric current must be a complete path returning to it's point of origin, Any break in the loop it fails.

High Energy electrons leave and low energy electrons return on the other side, along the way they did work for us. (the electrons don't actually move the whole path, kinda bounce around from this atom to that and then back again, but while they do so they pass along energy.)

So in the end the total mass is maintained in the solar panel it simply picks up energy from the sun in the form of heat, and gets rid of that extra energy by elevating eletrons in a copper wire to high orbits.