3 ms·

Then technically neither is wind, since it slows down surface air currents and widens the effective boundary layer of the atmosphere. Technically-technically,

by uoaei 3y ago

Then technically neither is wind, since it slows down surface air currents and widens the effective boundary layer of the atmosphere. Technically-technically, no forms of energy "generation" (technically just conversion) are 100% efficient so something is always lost to heat. I guess the important question is, what is the net effect in changing that kind of energy into purely thermal energy?

jval43 3y ago
Isn't wind created by temperature and pressure differentials between regions? How much is due to earth's rotation?
- uoaei 3y ago
  Quite a lot because of thermal expansion/contraction of air and differentials in incident sunlight heating the surface at different points at different times. Albedo, thermal mass of the objects being heated, etc., all contribute to a complex system of air and energy transport via air currents. It would take quite a lot of planning and work but maybe there are ways to mitigate these losses by balancing out the effects between different processes. Typically nature finds such dynamic equilibria as a matter of course -- I suspect anything humans attempt to control will not be as resilient or sound.
- btilly 3y ago
  A lot. Look up Hadley cells. https://groups.seas.harvard.edu/climate/eli/research/equable/hadley.html https://groups.seas.harvard.edu/climate/eli/research/equable... Warm air rises near the tropics, rotating with the Earth. It then goes towards the temperate zone, still rotating with the Earth to form the jet stream. It then falls, creating the trade winds as it slows down. It then is sucked back towards the tropics, creating a reverse trade wind because it is only going as fast as the temperate zone. And then it rises, completing the cycle. The prevailing wind in both temperate zones and the tropics is therefore due to the Earth's rotation.
  - dredmorbius 3y ago
    Hadley cells determine wind patterns but not the energy content of the wind, to any appreciable degree, which comes from solar flux. Wind energy is solar energy once removed. Wave energy is solar energy twice removed (solar -> wind -> waves).
    - btilly 3y ago
      Yes, the energy driving the entire system comes from the Sun. But the fact that it takes the form of wind rather than rising/falling columns of air has to do with the rotation of the Earth. Ditto for hurricanes. Hurricanes turn rising/falling air into cycling air into hurricane force winds because the Earth rotates. But the energy for it came from the Sun. Often removed by another factor, Sun warms ocean, ocean drives the storm.
      - dredmorbius 3y ago
        Wind is due to Earth's rotation much in the same way that airflow through ducts is due to the ducts. Earth's rotation directs the energy imbued by the Sun, much as ductwork directs airflow through a structure imbued by blower motors. But neither wind, nor ducted airflow, originate from, are driven by, or otherwise exhaust the Earth's rotation, or the containing ductwork, respectively. (Yes, there are frictional forces of the atmosphere against the Earth's surface. On balance these probably net out, as atmospheric flows at large scale are balanced, else we'd end up with a zone of vacuum and one of infinite pressure on the Earth's surface.) The original question was "How much [wind] is due to earth's rotation?", in the context of whether or not wind is a renewable energy resource. Given that wind is fundamentally driven by solar flux, wind is renewable, and it is not driven (vs. directed or influenced) in any meaningful way by Earth's rotation.
    - pyaamb 3y ago
      if we harvest wind do we still deplete waves?
      - dredmorbius 3y ago
NBJack 3y ago
Air currents have a purpose, and I actually believe large scale wind farming will have negative impacts on climate. Not to mention the impact on birds killed by the things. I would even go as far to say nuclear energy has less of an impact (as long as all goes well). The question few seem to ask is should we be this (literally) power hungry in the first place?
- uoaei 3y ago
  > The question few seem to ask is should we be this (literally) power hungry in the first place? Absolutely!! Reducing excess consumption will always be easier than making up for it later because the latter inevitably causes losses which become heat from which "useful work" can never be recovered. We can avoid those losses by simply never requiring them in the first place. But too many have the Myth Of Progress burrowed deep into their core ideologies and will fight tooth and nail to keep the trivial conveniences they've built their daily routines around. On your first point, though, I'm not sure it will be a net negative considering the human component in the equation, and anyway, outdoor cats are orders of magnitude worse for birds than wind turbines are, not to mention concrete jungles with no trees and high average noise levels.
- hedora 3y ago
  Nuclear does have less impact than wind, in terms of human lives lost volume of waste, and land usage. However, bird strikes can be mitigated via careful placement, etc. Also, we are not close to the point where wind farms impact wind currents.
- sgu999 3y ago
  Your first paragraph really made the second one a pleasant surprise! No we shouldn't be this power hungry, we've effectively never replaced an energy source by another... we keep on stacking the new ones on top of more of the old ones [1]. [1] https://ourworldindata.org/grapher/global-energy-substitution https://ourworldindata.org/grapher/global-energy-substitutio...
- hkt 3y ago
  > The question few seem to ask is should we be this (literally) power hungry in the first place? Nobody asks because the answer is "no" - huge parts of our lives are absurdly inefficient, wasteful, or just gratuitous when it comes to energy usage. Heating, transport, all of it. Computing, too.
dredmorbius 3y ago
No, wind is ultimately fed by solar energy and is driven by differential heating of Earth's atmosphere and surface. That is, there's a constant incoming energy flux. That's not to say that there isn't some maximum amount of available wind energy, or some maximum amount of energy that can be extracted from wind without causing other effects (even excepting, say, bird strikes and the like). But wind isn't "used up", there will be more wind tomorrow, so long as the sun shines and there's an atmosphere.
- pcthrowaway 3y ago
  But capturing wind surely creates a local warming effect? I believe I read that somewhere. Enough wind energy could accelerate global warming.
  - dredmorbius 3y ago
    That energy is already present in the environment, as kinetic energy of wind, which will ultimately be reduced to entropic heat. A wind turbine doesn't affect that fact, though it may change the location at which the kinetic -> thermal energy transformation occurs. The more likely impact would be of wind turbines removing sufficient energy from wind that thermal transport of the atmosphere itself is disrupted, though this would occur only within an immediate locale and at lower altitudes. Even very high turbines are only about 260 m (850 ft) tall. The mechanism here would be a reduction in the distribution of solar heating within the immediate vicinity, similar to urban heat island effects. And searching as I write this for "wind turbine heat island" I find precisely that mechanism described in this paper: Wind plants can also impact local atmospheric conditions through their wakes, characterized by reduced wind speed and increased turbulence. We explore the extent to which the wind plants near an atmospheric measurement site in the central United States have affected their long-term measurements. Both direct observations and mesoscale numerical weather prediction simulations demonstrate how the wind plants induce a wind deficit aloft, especially in stable conditions, and a wind speed acceleration near the surface, which extend ~30 km downwind of the wind plant. Turbulence kinetic energy is significantly enhanced within the wind plant wake in stable conditions, with near-surface observations seeing an increase of more than 30% a few kilometers downwind of the plants. "Wind plants can impact long-term local atmospheric conditions", Nicola Bodini, Julie K. Lundquist & Patrick Moriarty, Scientific Reports volume 11, Article number: 22939 (2021) <https://www.nature.com/articles/s41598-021-02089-2 https://www.nature.com/articles/s41598-021-02089-2> But that's not from energy transferred from the wind via the turbine, but of disruption of existing wind flows.

by uoaei 3y ago

jval43 3y ago

Isn't wind created by temperature and pressure differentials between regions? How much is due to earth's rotation?

uoaei 3y ago
Quite a lot because of thermal expansion/contraction of air and differentials in incident sunlight heating the surface at different points at different times. Albedo, thermal mass of the objects being heated, etc., all contribute to a complex system of air and energy transport via air currents. It would take quite a lot of planning and work but maybe there are ways to mitigate these losses by balancing out the effects between different processes. Typically nature finds such dynamic equilibria as a matter of course -- I suspect anything humans attempt to control will not be as resilient or sound.
btilly 3y ago
A lot. Look up Hadley cells. https://groups.seas.harvard.edu/climate/eli/research/equable/hadley.html https://groups.seas.harvard.edu/climate/eli/research/equable... Warm air rises near the tropics, rotating with the Earth. It then goes towards the temperate zone, still rotating with the Earth to form the jet stream. It then falls, creating the trade winds as it slows down. It then is sucked back towards the tropics, creating a reverse trade wind because it is only going as fast as the temperate zone. And then it rises, completing the cycle. The prevailing wind in both temperate zones and the tropics is therefore due to the Earth's rotation.
- dredmorbius 3y ago
  Hadley cells determine wind patterns but not the energy content of the wind, to any appreciable degree, which comes from solar flux. Wind energy is solar energy once removed. Wave energy is solar energy twice removed (solar -> wind -> waves).
  - btilly 3y ago
    Yes, the energy driving the entire system comes from the Sun. But the fact that it takes the form of wind rather than rising/falling columns of air has to do with the rotation of the Earth. Ditto for hurricanes. Hurricanes turn rising/falling air into cycling air into hurricane force winds because the Earth rotates. But the energy for it came from the Sun. Often removed by another factor, Sun warms ocean, ocean drives the storm.
    - dredmorbius 3y ago
      Wind is due to Earth's rotation much in the same way that airflow through ducts is due to the ducts. Earth's rotation directs the energy imbued by the Sun, much as ductwork directs airflow through a structure imbued by blower motors. But neither wind, nor ducted airflow, originate from, are driven by, or otherwise exhaust the Earth's rotation, or the containing ductwork, respectively. (Yes, there are frictional forces of the atmosphere against the Earth's surface. On balance these probably net out, as atmospheric flows at large scale are balanced, else we'd end up with a zone of vacuum and one of infinite pressure on the Earth's surface.) The original question was "How much [wind] is due to earth's rotation?", in the context of whether or not wind is a renewable energy resource. Given that wind is fundamentally driven by solar flux, wind is renewable, and it is not driven (vs. directed or influenced) in any meaningful way by Earth's rotation.
  - pyaamb 3y ago
    if we harvest wind do we still deplete waves?
    - dredmorbius 3y ago

NBJack 3y ago

Air currents have a purpose, and I actually believe large scale wind farming will have negative impacts on climate. Not to mention the impact on birds killed by the things. I would even go as far to say nuclear energy has less of an impact (as long as all goes well). The question few seem to ask is should we be this (literally) power hungry in the first place?

uoaei 3y ago
> The question few seem to ask is should we be this (literally) power hungry in the first place? Absolutely!! Reducing excess consumption will always be easier than making up for it later because the latter inevitably causes losses which become heat from which "useful work" can never be recovered. We can avoid those losses by simply never requiring them in the first place. But too many have the Myth Of Progress burrowed deep into their core ideologies and will fight tooth and nail to keep the trivial conveniences they've built their daily routines around. On your first point, though, I'm not sure it will be a net negative considering the human component in the equation, and anyway, outdoor cats are orders of magnitude worse for birds than wind turbines are, not to mention concrete jungles with no trees and high average noise levels.
hedora 3y ago
Nuclear does have less impact than wind, in terms of human lives lost volume of waste, and land usage. However, bird strikes can be mitigated via careful placement, etc. Also, we are not close to the point where wind farms impact wind currents.
sgu999 3y ago
Your first paragraph really made the second one a pleasant surprise! No we shouldn't be this power hungry, we've effectively never replaced an energy source by another... we keep on stacking the new ones on top of more of the old ones [1]. [1] https://ourworldindata.org/grapher/global-energy-substitution https://ourworldindata.org/grapher/global-energy-substitutio...
hkt 3y ago
> The question few seem to ask is should we be this (literally) power hungry in the first place? Nobody asks because the answer is "no" - huge parts of our lives are absurdly inefficient, wasteful, or just gratuitous when it comes to energy usage. Heating, transport, all of it. Computing, too.

dredmorbius 3y ago

No, wind is ultimately fed by solar energy and is driven by differential heating of Earth's atmosphere and surface. That is, there's a constant incoming energy flux. That's not to say that there isn't some maximum amount of available wind energy, or some maximum amount of energy that can be extracted from wind without causing other effects (even excepting, say, bird strikes and the like). But wind isn't "used up", there will be more wind tomorrow, so long as the sun shines and there's an atmosphere.

pcthrowaway 3y ago
But capturing wind surely creates a local warming effect? I believe I read that somewhere. Enough wind energy could accelerate global warming.
- dredmorbius 3y ago
  That energy is already present in the environment, as kinetic energy of wind, which will ultimately be reduced to entropic heat. A wind turbine doesn't affect that fact, though it may change the location at which the kinetic -> thermal energy transformation occurs. The more likely impact would be of wind turbines removing sufficient energy from wind that thermal transport of the atmosphere itself is disrupted, though this would occur only within an immediate locale and at lower altitudes. Even very high turbines are only about 260 m (850 ft) tall. The mechanism here would be a reduction in the distribution of solar heating within the immediate vicinity, similar to urban heat island effects. And searching as I write this for "wind turbine heat island" I find precisely that mechanism described in this paper: Wind plants can also impact local atmospheric conditions through their wakes, characterized by reduced wind speed and increased turbulence. We explore the extent to which the wind plants near an atmospheric measurement site in the central United States have affected their long-term measurements. Both direct observations and mesoscale numerical weather prediction simulations demonstrate how the wind plants induce a wind deficit aloft, especially in stable conditions, and a wind speed acceleration near the surface, which extend ~30 km downwind of the wind plant. Turbulence kinetic energy is significantly enhanced within the wind plant wake in stable conditions, with near-surface observations seeing an increase of more than 30% a few kilometers downwind of the plants. "Wind plants can impact long-term local atmospheric conditions", Nicola Bodini, Julie K. Lundquist & Patrick Moriarty, Scientific Reports volume 11, Article number: 22939 (2021) <https://www.nature.com/articles/s41598-021-02089-2 https://www.nature.com/articles/s41598-021-02089-2> But that's not from energy transferred from the wind via the turbine, but of disruption of existing wind flows.