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Question. Is extracting wind power causing some climate change problems?
- Thread starter Mountainmike
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Hans Blaster
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Wind extraction involves converting wind energy into mechanical energy using wind turbines.
It is not like a greenhouse effect as the process does not generate greenhouse gases.
The carbon footprint of wind turbines comes from the materials used in its construction.
The whole point behind wind turbines is to replace fossil fuel driven turbines to reduce CO₂ greenhouse emissions to allow more heat to radiate into outer space.
Here is some basic mathematics which shows land temperature does not play a role in the conversion of wind energy into mechanical energy.
The kinetic energy KE is defined by the equation.
KE = (1/2)mv².
Consider a cylindrical segment of moving air (wind) with velocity v, thickness x and diameter D corresponding to the diameter swept out by the blade of a wind turbine.
The wind has a velocity v and KE of the wind is.
KE = (1/2)mv² = (1/2)ρVv²
ρ is the air density (kg/m³).
V is the volume of the cylinder (m³).
The volume V = π(D/2)²x = π(D/2)²vt
where x = vt and t is the time (s).
The wind energy Ew in joules j is therefore.
Ew = (1/2)π(D/2)²ρv³t = (1/2)πr²ρv³t
where r=D/2 is the radius.
The energy from a wind turbine Ewt also in joules j is the mechanical energy and defined by the equation.
Ewt = (ηwt/100)Ew
ηwt is the wind turbine efficiency (%).
In theory the maximum efficiency of a wind turbine is 59% as governed by the Betz limit as explained in this video.
It is not like a greenhouse effect as the process does not generate greenhouse gases.
The carbon footprint of wind turbines comes from the materials used in its construction.
The whole point behind wind turbines is to replace fossil fuel driven turbines to reduce CO₂ greenhouse emissions to allow more heat to radiate into outer space.
Here is some basic mathematics which shows land temperature does not play a role in the conversion of wind energy into mechanical energy.
The kinetic energy KE is defined by the equation.
KE = (1/2)mv².
Consider a cylindrical segment of moving air (wind) with velocity v, thickness x and diameter D corresponding to the diameter swept out by the blade of a wind turbine.
KE = (1/2)mv² = (1/2)ρVv²
ρ is the air density (kg/m³).
V is the volume of the cylinder (m³).
The volume V = π(D/2)²x = π(D/2)²vt
where x = vt and t is the time (s).
The wind energy Ew in joules j is therefore.
Ew = (1/2)π(D/2)²ρv³t = (1/2)πr²ρv³t
where r=D/2 is the radius.
The energy from a wind turbine Ewt also in joules j is the mechanical energy and defined by the equation.
Ewt = (ηwt/100)Ew
ηwt is the wind turbine efficiency (%).
In theory the maximum efficiency of a wind turbine is 59% as governed by the Betz limit as explained in this video.
Last edited:
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Neutral Observer
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I fail to see the correlation. Friday was windy and 85 degrees, today it's windy and 40 degrees. One things for certain, if wind actually made things warmer I'd be living in one of the warmest places on earth, instead I'm wondering where the heck spring went.
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Walled gardens too have a microclimate , warmer than areas outside.
the question is not whether wind power extraction alters climate, it is by how much
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Bradskii
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I did some back of the envelope calcs just for fun. I worked out the total area of all the wind farms on the planet. Then the total area of all the sheep. There's not much of a difference.
What doesn't help is all the hot air being spouted by people who deny climate change.
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Bradskii
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If you watch trees closely it's pretty obvious that the more the branches are waving about, the windier it gets. But if a tree falls over in the forrest and there's no-one about, then we don't get wind of it.
High speed travel will actually cause a breeze. So if you get stopped for speeding, plead climate change in mitigation.
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An irrelevant calculation . To either the topic or science, can you stay on topic for once?
Who is denying climate change? Windmills are creating more of it.
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I see the argument that wind turbines can contribute to climate change as a direct feedback still has legs.
In my previous post the equations for the kinetic energy of the wind Ew and the energy of the wind turbine Ewt were derived.
To nip this argument once and for all the 1st law of thermodynamics needs to be brought into the picture.
The 1st law requires ΔE(universe) = 0 which is the conservation of energy law and ΔE(system) = q + w where q and w are the heat and work exchanged with the thermal and mechanical reservoirs respectively.
ΔE(system) is a constant and an increase in q results in a decrease in w and vice versa.
We can consider the Earth as being the system of the universe and the wind turbine as being the system.
In this case ΔE(system) = Ewt – Ew.
The engineering design for wind turbines is to maximize w so all the wind energy within the Betz limit is converted to mechanical energy which can only occur if q = 0.
Hence ΔE(system) = Ewt – Ew is the energy supplied by the wind as work, no heat is exchanged and therefore no direct impact on the climate.
In my previous post the equations for the kinetic energy of the wind Ew and the energy of the wind turbine Ewt were derived.
To nip this argument once and for all the 1st law of thermodynamics needs to be brought into the picture.
The 1st law requires ΔE(universe) = 0 which is the conservation of energy law and ΔE(system) = q + w where q and w are the heat and work exchanged with the thermal and mechanical reservoirs respectively.
ΔE(system) is a constant and an increase in q results in a decrease in w and vice versa.
We can consider the Earth as being the system of the universe and the wind turbine as being the system.
In this case ΔE(system) = Ewt – Ew.
The engineering design for wind turbines is to maximize w so all the wind energy within the Betz limit is converted to mechanical energy which can only occur if q = 0.
Hence ΔE(system) = Ewt – Ew is the energy supplied by the wind as work, no heat is exchanged and therefore no direct impact on the climate.
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Bradskii
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'...the Vikings going down by 12 points. And now some good news! Jessica?
'Yes, Pete. Severe winds have been forecast for the Mississippi area in the next couple of days. Apart from some minor structural damage, these winds will certainly help to reduce the effects of global warming by cooling the state down significantly. And I went down to the Delta wind farm in Tunica County to ask the operators if they will be turned off during the storm to help maximise airflow across the delta.'
'Sounds great, Jessica. And their response?'
'Well, Pete. Nothing we can actually show you as the language some of them used would not suitable for broadcast'.
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Hans Blaster
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