Further evaluation of windmills contributing to the Greenhouse effect as being pseudoscience.

[sjastro]

Here is the reference thread.

Question. Is extracting wind power causing some climate change problems?

From efficiency Wind farms take ( say) 40- 50 % of the available power. A plausibility argument: Wind is part of what is cooling land. So with less wind , the land WILL be hotter. That heat is part of the climate change problem. so is wind power extraction - at best unreliable - causing...

www.christianforums.com

Before going any further into the topic let’s introduce another ‘poster’ into the thread GPT-4o.
I have privately tested GPT-4o on various questions on general relativity and a question on quantum mechanics was addressed here.

AI learnt "something" from the Physical & Life Sciences Forum.

Can you try this with asteroid Vesta? What would the Bing AI say? I am betting it would say "The image contains a gray item in the center. It could be a hail stone on a black table or a pebble". :) This image summarizes the deficiencies in AI image recognition capabilities, in particular the...

www.christianforums.com

(Note the link incorrectly stated it was a GPT-3 response instead of GPT-4o.)

My opinion of AI being a valuable tool in science was sceptical to say the least until GPT-4o was released.
I tested GPT-4o on a third year applied mathematics exam on fluid mechanics, I took as an undergraduate many years ago.

If the OP had even a basic understanding of fluid mechanics, this thread would never have proceeded as it would have immediately been identified as pseudoscience.

GPT-4o’s initial exam result was very disappointing to say the least, it could not answer any of the questions.
It dawned on me however I may have added an extra layer of complexity by scanning the exam paper and inputting it into GPT-4o as an image file.
AI still has issues with understanding images so I decided to type the exam paper directly into GPT-4o’s input.
The results were chalk and cheese, in fact jaw dropping.

If I was to be nit-picky GPT-4o could have done a better job in detailing where some of the equations came from; fluid mechanics draws heavily on the pure mathematics subject of functions of complex variables and many of the equations are derived using Conformal map - Wikipedia.
GPT-4o passes the test and will be used to evaluate my comments and the OP’s in the following posts…….

 

[sjastro]

Now let’s get to GPT4-o’s evaluations starting with me.

The problems I had with the OP’s thread was a lack of science content which was based largely on personal opinion, a refusal to answer questions such as why his vague model was contradicted by temperature measurements, strawman comments and cherry picking of a reference which if quoted fully would have contradicted the model.

On top of this which puts the model fairly and squarely in the pseudoscience category was the insistence the downstream wind is permanently affected.
The difference between the velocity of the downstream wind tube and the surrounding wind is known as the velocity deficit and the only way to overcome the deficit is kinetic energy needs to be created which violates the conservation of energy which is the claim made by the OP.

This was a clear sign the OP either knows nothing about fluid mechanics or has an abysmal understanding of the subject.
As a result, I compiled a list of 10 criticisms with counterarguments where applicable based on the claims and actions taken by the OP in the thread. I asked GPT4-o to simply evaluate my criticisms/counterarguments and nothing more, as I did want to introduce the possibly of influencing GPT-o’s responses.

The comments are my criticisms/counterarguments and the evaluations are GPT4-o responses.

Your comments present a detailed critique of the original poster's (OP's) understanding of wind turbines and their environmental impact. Here's an evaluation of each point you made:

1. Confuses Turbulence Warming with Being a Greenhouse Effect

Comment:

• "Confuses turbulence warming with being a greenhouse effect."

Evaluation:

• Accurate: The OP seems to conflate local turbulence-induced warming with the greenhouse effect. The greenhouse effect is a specific process involving greenhouse gases trapping heat in the Earth's atmosphere, whereas turbulence-induced warming is a local effect due to kinetic energy dissipation.

2. Misunderstanding of Conservation of Energy and Turbulence

Comment:

• "Does not understand how the conservation of energy works; when air passes through the rotor blades heat is produced through turbulence. Since wind speeds very rarely reach up to 100 m/s, the upstream air is modelled as an incompressible fluid of low viscosity. On passing through the blades eddies are formed which carry TKE (Turbulent Kinetic Energy). Large scale eddies breakdown into a larger number of smaller eddies in an energy cascade process where the TKE is conserved. This process continues until the eddies reach a scale where further reduction is not possible and the eddies dissipate producing heat due to the internal friction of the air or in other words its viscosity."

Evaluation:

• Accurate and Detailed: Your explanation correctly describes the process of energy dissipation through turbulence and the concept of turbulent kinetic energy (TKE). It addresses the OP's misunderstanding of how energy conservation and dissipation work in the context of wind turbines.

3. Local Environmental Effects Due to Convergence

Comment:

• "Does not understand that while heat dissipation occurs inside the downstream wind tube, warming or cooling outside the tube which affects the local environment depends on the degree of convergence between the airflow inside the downstream tube with the exterior airflow."

Evaluation:

• Accurate: The degree of convergence between different airflows indeed affects local warming or cooling, which is a nuanced point that the OP seems to miss. This adds depth to the understanding of local environmental impacts.

4. Evidence of Local Warming and Cooling

Comment:

• "Ignores the evidence which supports point (3) where local warming occurs at night due to greater convergence as the thermal gradient is more stable at night with cooler air near the surface and warmer air above. During the day updrafts reduce the stability of the thermal gradient and less convergence occurs resulting in local cooling. During the day local cooling occurs as the sun heats the ground causing natural convection and mixing of air layers. Wind turbines enhance the mixing, resulting in a more even heat distribution which reduces temperatures at and near the surface. This totally contradicts windmills causing a global increase in temperatures."

Evaluation:

• Accurate: Your comment correctly points out the diurnal variations in thermal gradients and how wind turbines can enhance mixing, leading to local cooling during the day. This contradicts the OP's claim about a global temperature increase.

5. Concept of Reynolds Number

Comment:

• "Does not understand the concept of Reynolds Number which is the ratio of the inertial forces acting on a fluid divided by its viscosity. A practical demonstration of the Reynolds number is dipping one’s finger into a container full of air which has a high Reynolds number and into a container of maple syrup of low Reynolds number. On withdrawing the finger air immediately replaces the air displaced by the finger due to inertial forces while in the maple syrup the finger impression takes much longer to disappear."

Evaluation:

• Accurate and Informative: This is a good explanation of the Reynolds number and its practical implications, highlighting the difference between high and low Reynolds number flows. It underscores the OP's lack of understanding of fluid dynamics.

6. Limited Range of Downstream Wind Tube

Comment:

• "Does not understand the downstream wind tube has a limited range not global due to air’s high Reynolds number which causes it to dissipate rapidly and is also subject to local conditions."

Evaluation:

• Accurate: You correctly identify that the impact of the downstream wind tube is limited in range due to the dissipation of turbulence and local atmospheric conditions.

7. Physical Evidence from Radar

Comment:

• "Ignores the physical evidence provided by radar which shows the downstream wind tube has a limited range and not global."

Evaluation:

• Accurate: Radar evidence supports the limited range of the downstream effects, further contradicting the OP's claim of a global impact.

8. Continuity Equation and Downstream Tube Diameter

Comment:

• "Does not understand the diameter of the downstream wind tube is small due to the continuity equation which states the mass flow rate of the upstream wind equals the mass flow rate of the downstream wind. The diameter of the upstream wind tube cannot be any larger than the diameter of the circle swept out by the windmill rotor blades. Since the wind velocity is reduced on passing through the rotor, in order for the continuity equation to hold, the downstream tube cross sectional diameter equals A(v₁/v₂) where A is the cross-sectional diameter of the upstream tube and v₁, v₂ are the velocities of the upstream and downstream winds respectively."

Evaluation:

• Accurate: Your explanation of the continuity equation and its implications for the downstream tube diameter is correct. It emphasizes the OP's misunderstanding of basic fluid dynamics principles.

9. Local Scale Temperature Changes

Comment:

• "Ignores the physical evidence provided by temperature measurements, changes occur at a local scale due to the small diameter of the downstream tube and its rapid dissipation."

Evaluation:

Accurate: Temperature changes due to wind turbines are localized, which is supported by empirical evidence. Your comment accurately reflects this understanding.​

10. Misquoting Sources

Comment:

• "Engages in straight out lying by deliberately misquoting a source to support the case that windmills cause global warming when in fact the source supports the very opposite. This is what the authors actually wrote, “THEY FIND THAT DEPENDING ON THE ATMOSPHERIC CONDITIONS, the velocity deficit of the wind farm wake can be observed up to 100 km behind the wind farm, while the enhanced turbulence intensity can be observed up to 20 km DOWNSTREAM.” The capitalised parts are what were deliberately omitted in order to misquote the authors to create a completely different context."

Evaluation:

• Accurate: Deliberately misquoting sources to fit an argument is a serious issue. Your identification of the correct context provided by the authors helps clarify the misunderstanding or misrepresentation by the OP.

Overall Evaluation

Your comments provide a well-rounded, technically accurate, and detailed critique of the OP's assertions. They demonstrate a solid understanding of fluid dynamics, the principles of energy conservation, and the localized effects of wind turbines. Additionally, you correctly highlight the limitations of the OP's arguments and provide empirical evidence and theoretical principles to support your points.

The next post is for GPT4-o to evaluate a couple of the OP's comments.

 

[sjastro]

Here is GPT4-o's evaluation of two of the OP's posts.

Question. Is extracting wind power causing some climate change problems?

Do I need to remind you this thread is about the real effects of wind farms on the climate, not hypothetical turbine arrays numbering tens of thousands of wind turbines changing the path or strength of hurricanes. To coin your own phrase spare me this simplistic nonsense. If it is true you are...

www.christianforums.com

1. Energy Removal and Conservation:

The post correctly identifies that wind turbines remove kinetic energy from the wind, which affects downstream conditions. This is in line with the principle of conservation of energy. However, the explanation lacks detail on how this energy extraction manifests in changes to pressure, temperature, and velocity fields downstream.

2. Permanent Downstream Effects:

The assertion that downstream areas are "permanently affected" oversimplifies the situation. In fluid mechanics, the effects of energy extraction by wind turbines are significant in the near wake but diminish further downstream due to turbulent mixing and natural dissipation of energy. The term "permanently" is misleading because the impacts are not constant over long distances or time scales.

3. Basic Understanding of Fluid Dynamics:

The post rightly points out that changes in kinetic or potential energy must occur to balance the energy extracted by the turbines. However, it oversimplifies by not discussing the complex interactions and redistribution of energy within the flow, such as the conversion of kinetic energy into turbulent energy and its eventual dissipation.

4. Turbulence and Wake Dynamics:

The statement "Only the turbulence has finite trail" is correct, but it doesn't capture the complexity of wake dynamics. The wake created by turbines can persist for several kilometers, depending on factors such as atmospheric stability and turbine spacing. The turbulence within the wake is characterized by vortices and complex flow structures that influence how quickly the wake dissipates.

5. Historical Concerns and Expertise:

Mentioning Prof. BJ Cory and historical concerns is valuable for context. It is true that early researchers raised valid points about the potential impacts of wind turbines. However, fluid mechanics has advanced significantly since then, and many of these concerns have been studied extensively.

6. Ad Hominem and Tone:

The tone of the post is confrontational and includes ad hominem attacks, which are not productive in a scientific discussion. It would be more effective to focus on the scientific arguments rather than questioning the understanding or intelligence of others.

7. Synthetic Aperture Radar (SAR) Data:

The post mentions SAR data and its limitations but does not clearly link this to the discussion on wind turbines and energy extraction. While SAR is useful for mapping wind speeds and directions, its limitations in capturing the full complexity of wind turbine wakes and downstream effects should be better explained.

Question. Is extracting wind power causing some climate change problems?

You continue with blinkered vision, so your model is not useful at all. The question posed is the extent to which windmills alter microclimate , which they clearly do. As various others have noted in literature. But there is little consensus or indeed systematic testing, yet humanity races...

www.christianforums.com

1. Hurricanes and Microclimate:

• Overstated Claim: The comment suggests that technologies capable of changing the path or strength of hurricanes should not be considered as affecting only microclimates. While altering hurricanes is a significant intervention, the post's context seems to be wind turbines, which primarily affect local and regional scales rather than directly influencing large-scale phenomena like hurricanes.

2. Adiabatic Effects:

• Lack of Clarity: The reference to adiabatic effects causing condensation is somewhat vague. In fluid mechanics, adiabatic processes involve temperature changes due to pressure changes without heat exchange, but the specific mechanisms by which wind turbines induce these effects need clearer explanation.

3. Unmodeled Feedback Effects:

• Insufficient Detail: The mention of "second order unmodeled feedback effects" lacks specifics. While it is true that complex systems can have unanticipated feedbacks, a more detailed discussion of what these might be and how they could be studied or mitigated would strengthen the argument.

4. Thermoclines and Radar:

• Irrelevant Example: The reference to thermoclines and their impact on radar detection seems tangential. While it underscores the complexity of modeling and the importance of considering various factors, it is not directly related to the primary discussion on wind turbines and energy balance.

5. Ad Hominem Attacks:

• Unconstructive Tone: The comment contains several ad hominem attacks and a confrontational tone, which detracts from the scientific argument. Statements like "you seemingly can’t see past the end of your nose" are unhelpful and do not contribute to a productive discussion.

GPT4-o is far more diplomatic than I could have been, the thread is pseudoscience.
In the next post post GPT-4o is given free rein to give a comprehensive explanation as to why the velocity deficit can never be permanent.

 

[sjastro]

Finally GPT4-o gives a comprehensive explanation as to why the thread is pseudoscience, there are no permanent effects and the velocity deficit disappears.
I found GPT4-o's explanation most educational as it went beyond a purely fluid mechanics context.

1. Wake Mixing and Turbulence:

• Turbulent mixing in the wake of the turbine helps to transfer momentum from the surrounding higher-speed air into the slower-moving wake, gradually increasing the wind speed within the wake.
• As turbulence breaks down the wake structure, it aids in homogenizing the velocity field, reducing the velocity deficit over distance.

2. Atmospheric Stability and Turbulence:

• The stability of the atmosphere affects how quickly the wake recovers. In unstable atmospheric conditions, enhanced turbulence can lead to faster mixing and a quicker reduction of the velocity deficit.
• Conversely, in stable conditions, the wake may persist longer, and the velocity deficit may reduce more slowly.

3. Wind Shear:

Wind shear, the variation of wind speed with height, can contribute to the recovery of the wake. As higher-speed winds at different altitudes mix with the lower-speed wake, the overall wind speed within the wake increases.

4. Distance from the Turbine:

• The further downstream you go from the turbine, the more time and space there is for the turbulent mixing and momentum transfer processes to occur, leading to a gradual reduction of the velocity deficit.
• Typically, the velocity deficit diminishes with increasing distance from the turbine, eventually reaching the undisturbed wind speed far downstream.

5. Rotor Design and Operating Conditions:

• The design of the turbine rotor, including blade shape, size, and pitch, affects how the energy is extracted from the wind and how the wake is formed and dissipates.
• Optimized rotor designs can create a more efficient wake structure that recovers more quickly.
• The operating conditions, such as rotational speed and yaw angle, also influence wake characteristics.

6. Turbine Spacing and Wind Farm Layout:

• In wind farms, the spacing between turbines can affect wake recovery. Adequate spacing allows for more mixing and momentum transfer, reducing the overall impact of velocity deficits from upstream turbines on downstream turbines.
• The layout of the wind farm can be designed to optimize the flow and minimize the cumulative wake effects.

7. Ambient Wind Conditions:

• Ambient wind conditions, including wind speed and direction, play a crucial role in wake dynamics. Higher ambient wind speeds can help mix and disperse the wake more effectively.
• Changes in wind direction can also affect how the wake interacts with the surrounding air and other turbines.

8. Ground Roughness and Terrain:

• The roughness of the terrain and the presence of obstacles can influence wake behavior. Rougher terrains induce more turbulence, which can enhance wake recovery.
• Complex terrain, such as hills and valleys, can lead to varying wind patterns that affect wake dissipation.

9. Thermal Effects:

• Thermal stratification and heating effects can create buoyancy-driven flows that influence wake behavior. For instance, solar heating of the ground can create thermals that mix the air and enhance wake recovery.

In summary, the reduction of the velocity deficit downstream of a wind turbine is a complex process influenced by aerodynamic, atmospheric, and environmental factors. Turbulent mixing, atmospheric conditions, rotor design, turbine spacing, ambient wind conditions, terrain, and thermal effects all play a role in how quickly and effectively the wake recovers, ultimately reducing the velocity deficit to zero.

 

[sjastro]

As an experiment I made a statement which had a built in subtle error involving the Navier Stokes equation.

These equations are extensively used in physics, climate models are an important application but they present a challenge in mathematics as no one has been able to prove whether the momentum equations in three dimensions have smooth solutions (infinitely differentiable at every point).
A million dollars waits for any mathematician who is able to solve this problem.

The statement I made for GPT4-o to evaluate was "The Navier Stokes equation has a diffusion term µ∇²v which means the range of the downwind stream tube has a local scale."

I'll leave it to GPT4-o to show the error.

Evaluation of the Statement:

"The Navier-Stokes equation has a diffusion term μ∇²v which means the range of the downwind stream tube has a local scale."

Breakdown of the Statement:

1. Navier-Stokes Equation and Diffusion Term:
   
   • The Navier-Stokes equation is a fundamental equation in fluid mechanics that describes the motion of fluid substances. The term μ∇²v, where μ is the dynamic viscosity and ∇²v is the Laplacian of the velocity vector v, represents the diffusion of momentum due to viscosity. This term is responsible for the spread of momentum in the fluid, smoothing out velocity gradients.
2. Interpretation of the Diffusion Term:
   
   • The diffusion term μ∇²v indeed indicates how momentum diffuses through the fluid. It describes how viscosity acts to dissipate energy and smooth out variations in the velocity field.
3. Range of the Downwind Stream Tube:
   
   • The term "range of the downwind stream tube" refers to the extent to which effects such as changes in velocity and turbulence propagate downstream of an obstacle (like a wind turbine). The statement implies that this range is determined by the local scale of momentum diffusion.

Accurate Points:

1. Presence of Diffusion Term:
   
   • It is correct that the Navier-Stokes equation contains a diffusion term μ∇²v, which represents viscous diffusion in the fluid.
2. Local Scale of Viscous Effects:
   
   • The diffusion of momentum due to viscosity does act on a local scale, influencing the immediate vicinity around points of velocity gradients.

Problematic Points:

1. Simplification of Downwind Effects:
   
   • The statement oversimplifies the range of the downwind stream tube by attributing it solely to the viscous diffusion term. While μ∇²v affects the dissipation of energy and smoothing of velocity gradients, the range of downstream effects is also influenced by other factors, including:
     
     • Inertia: The convective term (u·∇)u in the Navier-Stokes equation, representing the transport of momentum by the flow itself.
     • Turbulence: Turbulent flows introduce complex interactions and energy cascades that significantly extend the range of downstream effects.
     • Boundary Conditions: The physical boundaries and obstacles in the flow field also impact the behavior of the downstream stream tube.
2. Viscous Dominance vs. Turbulent Flow:
   
   • In many practical applications, especially at high Reynolds numbers (indicative of turbulent flow), the convective and inertial effects often dominate over viscous diffusion. The local scale effect of viscosity is more pronounced in laminar flows, where the Reynolds number is low.

Revised Statement for Clarity:

"The Navier-Stokes equation includes a diffusion term μ∇²v, which represents the local-scale effects of viscous diffusion. However, the range of the downwind stream tube is influenced by a combination of viscous diffusion, convective transport, and turbulent mixing. In high Reynolds number flows, inertial and turbulent effects often play a more significant role than viscous diffusion in determining the extent of downstream effects."

Summary:

• The Navier-Stokes equation indeed has a diffusion term μ∇²v, which represents the local-scale diffusion of momentum due to viscosity.
• The range of the downwind stream tube is not determined solely by this diffusion term. It is also influenced by convective transport and turbulence, especially in high Reynolds number flows.
• The statement oversimplifies the complexity of downstream effects by focusing only on viscous diffusion.

I felt like I was being given a lecture.

 

[Nithavela]

TL/DR