1. Jun 19, 2009

### northern expo

As we have been instructed for years that there is no energy that can be obtained (perpetual motion) so how can we expect that the increase of wind power is electrical energy for free? If we use wind to obtain energy will this wind energy loss from our environment have an adverse affect on our planet, weather conditions, etc. Hmmmm, maybe the roation speed of theplanet could be slowed if enough winddmills were place causing a resistance enough to slow the planet's rotation? Think I'm just crazy or can we get it for free?

2. Jun 19, 2009

### Pengwuino

It's not a crazy idea. The energy is indeed pulled out of the atmosphere. I don't believe the rotation of the earth would be affected by any dramatic amount though. I'm not sure if any study has been done about the effects of pulling that energy out of the atmosphere. I suspect it probably is because it's such a negligable amount that no ones bothered. Then again who knows! Do some order of magnitude calculations and see what you get. Point is though, the energy isn't free and it does come out of the atmosphere (via wind).

3. Jun 19, 2009

### Astronuc

Staff Emeritus
Sun light is free, i.e. it doesn't cost anything. It provides light and warmth. It's there whether used or not.

We take a small fraction of the total wind energy through windmills. The cost of wind energy is the capital cost of the windmills.

The suns energy, gravity and the rotation of earth drive the convection in the atmosphere that produces wind.

4. Jun 19, 2009

### Bob S

Wind power extracted for our use as electricity removes energy which otherwise would heat the air (kinetic energy) and our environment. Because we use this energy for running lights, refrigerators, and all the other conveniences of modern life, we are putting that energy back into the environment as heat. Our environment would be better off if we converted that electricity into microwave power and radiate it into interplanetary space.

5. Jun 19, 2009

### denisv

Define 'better'.

6. Jun 19, 2009

### Bob S

From Bob S
Our environment would be better off if we converted that electricity into microwave power and radiate it into interplanetary space.
"better" is equivalent to Global Cooling.

7. Jun 19, 2009

### diazona

When people talk about energy sources (coal, nuclear, wind, solar, etc.), I get the impression that "free" seems to mean something different than it does in physics - namely, "free" energy is energy which can be obtained with no adverse effects on the environment (i.e. no emission of CO2, no radioactive waste, etc.) Essentially it's "free" in the sense that there's no cost associated with cleaning up after it.

Although, it's far more common that I hear those forms of energy production being called "renewable" or "clean" or "green".

8. Jun 19, 2009

### denisv

How is that better, and according to whom is it better?

9. Jun 19, 2009

### RonL

According to me, I live in Texas and it's hotter than heck here.

10. Jun 19, 2009

### Phrak

Stored for the winter, it costs me anywhere from 200 to 300 dollars a cord.

Converted to electricity, no solar cell manufacturer would ever consider it worth collecting on the roof.

11. Jun 19, 2009

### Phrak

Even with this definition, the concept is delusional. It takes a large amout of coal and petroleum to mine, manufacture and dispose of solar cells, for instance.

Last edited: Jun 19, 2009
12. Jun 19, 2009

### diazona

Even if that's true now, it may not always be true in the future.

Do you have data regarding how the amount of energy released by burning a certain amount of coal/petroleum compares with the amount of energy that can be collected by using it to create solar cells?

13. Jun 19, 2009

### Phrak

I started on this, I couldn't find collaborating data, and found better things to do. About 20 to 50% if you are willing to pay 2 to three times the price, or create a third world economy by forcing everyone to do it.

14. Jun 19, 2009

### Phrak

You are speaking of abstract environs where people aren't in it. It's a little difficult to sell a point to humans on this thead where our welfare is discounted to nil.

15. Jun 19, 2009

### Staff: Mentor

I think someone has posted link on the subject last year on PF. Don't ask me about details, but if memory serves me well - there is already a net gain in energy (that is, amount of solar energy converted to electricty in the lifetime of cells is higher than amount of energy required to produce them). That was not always the case, it must have changed after 2000.

16. Jun 19, 2009

### Staff: Mentor

I think the OP's concern is the effect of harvesting that energy instead of letting it hit the earth.

Basically, one must consider these issues when harvesting energy from the environment, but I think you'll find that the amount of energy that we would/could harvest in the form of wind or solar is too small to affect the global energy balance. Other ecosystem issues may exist, though (such as wind farms killing birds).

The same cannot be said for hydro power, though....

17. Jun 19, 2009

### Pengwuino

That sounds strange. I can't imagine solar panels would be even close to a possible net loss in energy to create them. That wouldn't even make sense, why would we even bother if it's that bad? Maybe I'm not thinking about it right...

18. Jun 19, 2009

### Phrak

Now I recall. I considered, first, the cost of the solar panels and installation. There is also the dollars, energy cost and efficiency factor of the conversion equipment to put it in usable alternating current form--or not. Perphaps you will run staight DC. How much is the amortized battery storage cost? That depends on your preferences. Also, local insolation varies substancially from place to place and season to season--more variables.

So it depends on each implimentation.

19. Jun 20, 2009

### Staff: Mentor

It is not energy balance that counts, but cost of kWh at the place you need it. If it is cheaper using solar panels than connecting to the grid, panels win, no matter how much energy was needed to produce them.

20. Jun 21, 2009

### harvellt

Well I have a couple things.
No idea on the amount of fossil fuel energy spent vs return but this stuff is way cool!
One is Japan has a pretty serious plan for an orbiting solar array.

http://www.scientificamerican.com/article.cfm?id=farming-solar-energy-in-space
If this thing can orbit with little to no maintenance then energy produced should easily surpass the initial energy cost.

This one is just friken cool. If this becomes more efficient and we start extending it to all our gadgets (mp3, laptop, kindle, whatever...) I think energy "savings" would add up.
http://www.technologyreview.com/communications/22764/