Wind Power Long Term Sustainability

[fiveworlds]

What is the long term effect of wind energy on the planet? Is it really as sustainable as it is made out to be? 
We see videos about dams in china that supposedly slowed down the rotation of the earth. If wind power was to be scaled out what would the effect be?

How sustainable are the parts used in wind farms. There are various articles about them winding up in landfills after a few years what are the challenges around recycling them and how many years do they need to operate to recoup the energy costs associated with building and recycling them?

[swansont]

9 hours ago, fiveworlds said:

What is the long term effect of wind energy on the planet? Is it really as sustainable as it is made out to be? 
We see videos about dams in china that supposedly slowed down the rotation of the earth. If wind power was to be scaled out what would the effect be?

Can you post the info here, so we don’t have to wade through a video?

[John Cuthber]

14 hours ago, fiveworlds said:

dams in china that supposedly slowed down the rotation of the earth.

"NASA has calculated that the dam only slows the rotation by 0.06 microseconds"
Watch me not care.

The effects of harvesting wind power will be comparably small.

[TheVat]

3 Gorges project concentrates an enormous mass of water, 42 billion tons, in a small area.   Wind installations do nothing remotely comparable in shifting large masses.   

Turbine blades are presently difficult to recycle, but they last decades and produce an amount of KwH which,  if produced by fossil fuels, would involve far more CO2 release, as well as potential methane release from leaky extraction operations, and groundwater pollution.   

Say hello for me to your pals at the Heartland Institute!  

[Ken Fabian]

It is not that renewable energy tech has no problem waste, but that fossil fuel use makes so, so, so much problem waste - without any real way to reduce it. Even leaving aside CO2, the waste from fossil fuels is enormous, such as 1 billion metric tons a year of heavy metals contaminated coal ash alone. But there is no leaving aside CO2; that is the point of shifting away from fossil fuels. We might visit municipal landfill sites and think that is a lot of waste but coal ash (fly ash) waste pits and ponds are much larger - just out of sight and usually off limits to the public. And leaving enduring problems.

The wind power (and solar and battery waste) problem looks small in comparison; the RE industry would have to try hard at being dirty to come anywhere close.

The renewable energy sector in most developed nations support the development of recycling as safe waste management - even willing to include pre-payment provisions in purchase contracts to support it. The fossil fuel sector still fiercely opposes any accountability for their waste.

[mistermack]

On 9/5/2021 at 11:14 PM, fiveworlds said:

We see videos about dams in china that supposedly slowed down the rotation of the earth.

The good news is that the melting of the Greenland ice sheet will speed it back up. So no need to adjust your alarm clock just yet. 

[ScienceNostalgia101]

Wind is basically a massive convection current, lifting warm air over the tropics and sinking it over the poles. It stands to reason that if we built enough wind turbines to harness a non-trivial fraction of the wind's kinetic energy, the poleward transfer of heat would be somewhat reduced, and the polar amplification aspect of climate change in particular would in turn be reduced. This on the whole would be a good thing; less Arctic/Antarctic ice melt. (However much wasn't also prevented by the implied transition to renewables.)

[studiot]

4 hours ago, ScienceNostalgia101 said:

Wind is basically a massive convection current, lifting warm air over the tropics and sinking it over the poles. It stands to reason that if we built enough wind turbines to harness a non-trivial fraction of the wind's kinetic energy, the poleward transfer of heat would be somewhat reduced, and the polar amplification aspect of climate change in particular would in turn be reduced. This on the whole would be a good thing; less Arctic/Antarctic ice melt. (However much wasn't also prevented by the implied transition to renewables.)

 

Since this thread is in Earth Science, I suggest you get your old Geography books out and look at them, as you have several serious misconceptions in that post.

 

Wind blows essentially horizontally, not vertically.
Different winds blow horizontally at different altitudes and rarely direct connect.

 

Luckily for you the main transfer of (solar) heat from the tropics to the poles is by ocean currents, not winds.
This redistribution is vital to making vast areas of the planet's dry land habitable.
When talking of currents, the water rises and descend in 'gyres', currents like winds, are more or less horizontal.
You should also distinguish between tidal streams which use gravitationally derived energy and currents.

 

 

[TheVat]

Plus one.   Yes,  winds are a complex phenomenon where topography, uneven land surface heating,  the earth's rotation and Coriolis effect,  altitude,  and an array of influences all play a role. 

 

We could never place enough windmills to have more than a miniscule effect on the overall transfer of thermal energy on the planet. 

 

[Ken Fabian]

The changes to the climate and weather patterns from global warming will have a bigger impact on winds, local and global average, than the atmospheric impacts of wind farms.

[swansont]

18 hours ago, ScienceNostalgia101 said:

Wind is basically a massive convection current, lifting warm air over the tropics and sinking it over the poles. It stands to reason that if we built enough wind turbines to harness a non-trivial fraction of the wind's kinetic energy, the poleward transfer of heat would be somewhat reduced, and the polar amplification aspect of climate change in particular would in turn be reduced. This on the whole would be a good thing; less Arctic/Antarctic ice melt. (However much wasn't also prevented by the implied transition to renewables.)

What is the amount of wind power in the world, that we might harness a non-trivial fraction? I would expect a lot of it is away from the ground, like the jet stream.

[Ken Fabian]

On 11/4/2021 at 2:34 AM, ScienceNostalgia101 said:

Wind is basically a massive convection current, lifting warm air over the tropics and sinking it over the poles

Convection from the tropics doesn't carry air to the poles, just to mid-latitudes - with global warming causing the Hadley cells to expand to higher latitudes, something of concern here in Australia, as Hadley cells are associated with the high pressure systems that bring dry weather and push hot air from Australia's inland to the coast and are making the dry zones bigger.

Not sure if enough warming could cause merging of Ferrel and Hadley cells or otherwise change this basic pattern of air circulation - messing with the climate has consequences -

[ScienceNostalgia101]

21 hours ago, swansont said:

What is the amount of wind power in the world, that we might harness a non-trivial fraction? I would expect a lot of it is away from the ground, like the jet stream.

How much more expensive would it be to harness jet stream wind, though? If the gov't were to impose on aircraft manufacturers a requirement to build wind turbines fitted to their aircrafts, would this constitute a significant impediment on their ability to be flown, or a minor one? If one were to structurally reinforce a several kilometre tall wind turbine to withstand the torque applied by the wind, would this require significantly more maintenance costs than an ordinary wind turbine, or would it be a one-time investment that would pay for itself?

 

My apologies for neglecting to consider ocean currents. That said, I am aware of Hadley Cells and was referring to the net effect of the atmosphere in the "initial position, final position" sense (ie. treating the horse latitude downdrafts and midlatitude updrafts as cancelling out).

[swansont]

3 hours ago, ScienceNostalgia101 said:

If one were to structurally reinforce a several kilometre tall wind turbine to withstand the torque applied by the wind, would this require significantly more maintenance costs than an ordinary wind turbine, or would it be a one-time investment that would pay for itself?

Nobody has built a structure that tall. And it would likely cost a minimum of a billion dollars (4x the cost of the CN tower)

 

added:

Lets say you could get a 10MW system on the tower; you'd generate a little less than 100,000 MWh if it ran at full capacity 100% of the time.  That's 10^8 kWh, and if you could sell the electricity at $0.10 per kWh, that's $10 million a year. It would take 100 years to pay off a  structure 

[John Cuthber]

There is a fundamental difference between the dam and a wind turbine.

The dam moves a huge mass slightly further from the centre of the Earth; this changes the moment of inertia of the earth and therefore affects the rate of rotation because the angular momentum is fixed.

The wind turbine doesn't.

So it won't affect the rotation rate.

[swansont]

17 minutes ago, John Cuthber said:

There is a fundamental difference between the dam and a wind turbine.

The dam moves a huge mass slightly further from the centre of the Earth; this changes the moment of inertia of the earth and therefore affects the rate of rotation because the angular momentum is fixed.

The wind turbine doesn't.

So it won't affect the rotation rate.

Wind has momentum, and that's reduced when the turbine harvests some of its KE. I think the argument here is that wind direction is not uniform (especially near the surface) and momentum is a vector, so these effects tend to cancel.

 

 

[John Cuthber]

On 11/5/2021 at 11:37 AM, swansont said:

Wind has momentum, and that's reduced when the turbine harvests some of its KE. I think the argument here is that wind direction is not uniform (especially near the surface) and momentum is a vector, so these effects tend to cancel.

 

 

No.

Not "tends to cancel" but "absolutely has to cancel".

The Earth is pretty much isolated so the angular momentum is conserved. (Ignoring tidal coupling to the moon etc)

Since the moment of inertia is also unchanged the rate of rotation can not change.

 

Yes, the wind provides a torque on the turbine, but only because the planet provided a torque on the wind in the first place.

[swansont]

34 minutes ago, John Cuthber said:

No.

Not "tends to cancel" but "absolutely has to cancel".

The Earth is pretty much isolated so the angular momentum is conserved. (Ignoring tidal coupling to the moon etc)

Since the moment of inertia is also unchanged the rate of rotation can not change.

 

Yes, the wind provides a torque on the turbine, but only because the planet provided a torque on the wind in the first place.

The rotation rate changes all the time; the length of the day fluctuates on the scale of a millisecond over perhaps a month

The angular momentum of the entire earth is basically constant, but that does not mean the rotation rate is. Mass moves around. Hurricanes/typhoons/tornadoes rotate and have angular momentum.  Ocean currents change. The earth shape is slowly changing as ice melts (one of the suspects in the recent speedup of earth rotation)

https://hpiers.obspm.fr/eop-pc/page_princ_frame2.html

https://www.nasa.gov/centers/goddard/news/topstory/2003/0210rotation.html

The variability of earth rotation is why it’s not used for precision timekeeping.

[John Cuthber]

The Earth's rotation slows slightly when I go upstairs and rises again when I come back down.
But the point remains that apart from the tiny effect of lifting some mass- that of the turbine and tower- using  a wind turbine won't stop the earth rotating.

Building the tower makes a difference, using it doesn't.

If the wind didn't hit the tower then it would be slowed down by drag against the earth anyway.

The rotation of the rock we are stood on changes.

The rotation of the atmosphere also changes.

But the rotation of the whole earth- including the geosphere and atmosphere pretty nearly doesn't. There's a tiny effect because, when the earth is nearer the sun, it warms and the atmosphere expands.

The reason you can't use the rotation of the earth as a much better clock is that you only measure the rotation of part of it.
If you could include the air as well, the whole earth would keep much better time.