Physics of wind power

smudge · #1 by **smudge** » Jun 13, 2011 9:01 am

I was debating Climate change with a denier recently and the subject of wind power came up.
He was suggesting that if you take power from wind you will eventually run out of wind! My response was to laugh, we are never going to build enough turbines to effect the wind to that extent. But it got me thinking. There must be some sense to this (though I doubt that we will run out of wind)! Physics is not my strong point but the law of conservation of energy must come into play. There must be an effect on wind itself if we take power from it. Right?

Wave power too. If it is the case that taking energy from waves depletes that energy, then are we actually depleting waves? Sounds dumb, but there must be some sense to it...?!

Can somebody please set me straight on the science?

z8000783 · #2 by **z8000783** » Jun 13, 2011 9:03 am

Not dumb at all, entirely correct except what we take is so minuscule you will never notice it.

John

Animavore · #3 by **Animavore** » Jun 13, 2011 9:13 am

Wait - how is that correct? I thought wind was driven by the rotation of the Earth. Wind turbines surely can't take from the mechanism. Won't it just keep generating wind?

z8000783 · #4 by **z8000783** » Jun 13, 2011 9:24 am

The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Animavore · #5 by **Animavore** » Jun 13, 2011 9:33 am

You're taking the piss. Right?

LucidFlight · #6 by **LucidFlight** » Jun 13, 2011 9:52 am

Where Does The Wind Come From?

The source of the wind is the sun. The winds come from the suns energy falling on the earth’s surface. Due to the orientation of the earth’s surface to the sun’s rays near the equator the rays strike the surface at more optimum angles. The effect is that the air near the surface in tropical regions is heated more than the air near the surface of the polar regions. This leads to convection currents in the atmosphere, ie the movement of air due to changes in its density and pressure. This air movement is the principal cause of the winds.

http://www.claverton-energy.com/where-d ... there.html

How much wind is there?

Smil gives a figure, 3.8 x 1022 Joules, for the annual flux for the winds in the atmosphere below a height of 1km(2). He puts the maximum convertible at 3.8 x 1021 Joules or 1.1 x 106 TWh.

http://www.claverton-energy.com/how-muc ... n-ltd.html

campermon · #7 by **campermon** » Jun 13, 2011 6:44 pm

z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

...but if you jumped up the ground would rotate beneath you so you wouldn't be affected by the time travelling backwards..

:coffee:

z8000783 · #8 by **z8000783** » Jun 13, 2011 6:46 pm

magikrooster · #9 by **magikrooster** » Jun 27, 2011 6:59 am

z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Surely then, we can just turn the windmills the other way?

hackenslash · **#10** by **hackenslash** » Jun 27, 2011 7:10 am

Wind is just the equalisation of pressure differentials. As with all processes involving energy, it is subject to entropy, so it is finite. However, the energy we extract from it is immeasurably insignificant, and will remain so, quite probably. I doubt we'll ever have the means to seriously affect the distribution of atmospheric pressure differentials, and they continue to be produced, as Jay rightly pointed out.

z8000783 · **#11** by **z8000783** » Jun 27, 2011 7:13 am

magikrooster wrote:
z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Surely then, we can just turn the windmills the other way?

No, we can't do that because they would then suck all the electricity back in again and the lights will go out.

John

hackenslash · **#12** by **hackenslash** » Jun 27, 2011 7:19 am

The_Metatron · **#13** by **The_Metatron** » Jun 27, 2011 10:06 am

John's in rare form today.

magikrooster · **#14** by **magikrooster** » Jun 27, 2011 2:04 pm

z8000783 wrote:
magikrooster wrote:
z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Surely then, we can just turn the windmills the other way?

No, we can't do that because they would then suck all the electricity back in again and the lights will go out.

John

Wow sounds like some kind of high tech weapon. Does the military know about this?

rEvolutionist · **#15** by **rEvolutionist** » Jun 27, 2011 2:20 pm

I just thought of a killer idea for the mother of all wind turbines. Stick a giant turbine/windmill thingo (probably about the size of England, say) in space so that as the earth rotates, its atmosphere passes over the windmill thingo and produces so much power that we could leave our tv's on 24 hours a day. We just need somewhere to anchor the thing so that the earth doesn't drag it along with it. Maybe a wormhole or something. :think:

RobbieN30 · **#16** by **RobbieN30** » Jan 05, 2012 8:17 am

z8000783 wrote:
magikrooster wrote:
z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Surely then, we can just turn the windmills the other way?

No, we can't do that because they would then suck all the electricity back in again and the lights will go out.

John

WHAT?!?!

hahaha, but funny as it is,

the idea of the wind losing power, really maybe could be affected,
its power could be lessened after they go through turbines.

Rob

rainbow · **#17** by **rainbow** » Jan 05, 2012 8:37 am

magikrooster wrote:
z8000783 wrote:
magikrooster wrote:
z8000783 wrote:The Earth will slow down as well and if you take to much wind we will start rotating backwards.

John

Surely then, we can just turn the windmills the other way?

No, we can't do that because they would then suck all the electricity back in again and the lights will go out.

John

Wow sounds like some kind of high tech weapon. Does the military know about this?

The Controllers are aware.
...and they know where you live.

Tyrannical · **#18** by **Tyrannical** » Jan 05, 2012 9:03 am

I suppose in theory many windmills could alter local weather / wind patterns.

Slightly scarier would be water turbines sapping energy from the Gulf Stream. If that altered the stream's course it could throw the UK into a deep freeze.

wikipedia

The Gulf Stream transports about 1.4 petawatts of heat, equivalent to 100 times the world energy demand,[35] and research into different ways to tap this power is being undertaken. One idea, which would supply the equivalent power of several nuclear power plants, would deploy a field of underwater turbines placed 300 metres (980 ft) under the center of the core of the Gulf Stream, such as being developed by Aquantis, LLC.[36] Ocean thermal energy could also be harnessed to produce electricity utilizing the temperature difference between cold deep water and warm surface water.[37]

rainbow · **#19** by **rainbow** » Jan 05, 2012 9:11 am

Tyrannical wrote:I suppose in theory many windmills could alter local weather / wind patterns.

Slightly scarier would be water turbines sapping energy from the Gulf Stream. If that altered the stream's course it could throw the UK into a deep freeze.

OK. Why is this a problem?

LucidFlight · **#20** by **LucidFlight** » Jan 05, 2012 9:14 am

rainbow wrote:
Tyrannical wrote:I suppose in theory many windmills could alter local weather / wind patterns.

Slightly scarier would be water turbines sapping energy from the Gulf Stream. If that altered the stream's course it could throw the UK into a deep freeze.

OK. Why is this a problem?

Exactly. Bring it on, I say! :nod: