5 ms·

Another thing I heard about wind energy recently was that the friction of the blades significantly warms the air, so if deployed at scale, the total effect on a

Another thing I heard about wind energy recently was that the friction of the blades significantly warms the air, so if deployed at scale, the total effect on atmospheric warming would not be as beneficial as hoped. Not sure how valid it is, but I thought it was interesting and hadn't heard it before.

63 5y ago
I'm by no means an expert here, but wouldn't the energy that is expressed as heat in that friction just be the energy that's already in the air? Wouldn't it just be expressed as heat and friction anyway as air moves past other objects and other air? It doesn't make sense that turbines would be putting more energy into the system than they're taking out.
- kergonath 5y ago
  That would be another kind of perpetual motion/unlimited energy production device.
- Arnavion 5y ago
  In an ideal frictionless encounter between air particle and turbine blade, the particle loses some kinetic energy and the blade gains the same kinetic energy. In a real encounter with friction, some of the KE is lost to heat. The initial source of the particle's KE was heat from the Sun causing weather. So the net energy is constant, the local temperature is higher because the blade has heated up at the cost of the air particle's motion, but overall temperature is the same because more heat from the sun will be needed to restore the air particle's motion that was lost to friction. It all balances out in the end. The fact that the total energy is the same doesn't necessarily mean it's okay. Hypothetically if wind turbines set up a gradient so that the first few meters of atmosphere become hotter and the rest of the atmosphere becomes colder, total energy is conserved, but it's not a desirable outcome. But I don't know if humans can build enough wind turbines to make that possible; the Earth is very big and the atmosphere has a lot of mass.
colechristensen 5y ago
That is not even remotely valid, the easiest way to think about it is through energy conservation: the atmosphere would have to be significantly heating itself from energy it already had.
- tzs 5y ago
  Does all the energy to run a wind turbine come from the energy produced by that turbine's blades? I'd expect several components of a wind turbine to require power. Its electronic components may need power for cooling or heating depending on the season. The motors that change the blade pitch need power. Some of these things need to work when the blades are stopped. One way to do that would be to power them from the grid instead of from the turbine. If those things are grid powered, then a wind turbine might actually very very very slightly raise local atmospheric temperature. Anyone here happen to know if they actually do power anything in the turbine from the grid, or if they do something else like power such things from batteries that get recharged by the turbine when it is generating power?
kergonath 5y ago
That's bullshit. They can plausibly cause some surprising changes by disturbing the local air circulation patterns (which can either increase or decrease temperatures at a very local level), but increasing the temperature because of friction is a fantasy. If this were happening at a significant scale, it would decrease atmospheric temperatures, because the energy that ends up heating the blades would have to come from somewhere, and the air would lose some of its kinetic energy.

63 5y ago

I'm by no means an expert here, but wouldn't the energy that is expressed as heat in that friction just be the energy that's already in the air? Wouldn't it just be expressed as heat and friction anyway as air moves past other objects and other air? It doesn't make sense that turbines would be putting more energy into the system than they're taking out.

kergonath 5y ago
That would be another kind of perpetual motion/unlimited energy production device.
Arnavion 5y ago
In an ideal frictionless encounter between air particle and turbine blade, the particle loses some kinetic energy and the blade gains the same kinetic energy. In a real encounter with friction, some of the KE is lost to heat. The initial source of the particle's KE was heat from the Sun causing weather. So the net energy is constant, the local temperature is higher because the blade has heated up at the cost of the air particle's motion, but overall temperature is the same because more heat from the sun will be needed to restore the air particle's motion that was lost to friction. It all balances out in the end. The fact that the total energy is the same doesn't necessarily mean it's okay. Hypothetically if wind turbines set up a gradient so that the first few meters of atmosphere become hotter and the rest of the atmosphere becomes colder, total energy is conserved, but it's not a desirable outcome. But I don't know if humans can build enough wind turbines to make that possible; the Earth is very big and the atmosphere has a lot of mass.

colechristensen 5y ago

That is not even remotely valid, the easiest way to think about it is through energy conservation: the atmosphere would have to be significantly heating itself from energy it already had.

tzs 5y ago
Does all the energy to run a wind turbine come from the energy produced by that turbine's blades? I'd expect several components of a wind turbine to require power. Its electronic components may need power for cooling or heating depending on the season. The motors that change the blade pitch need power. Some of these things need to work when the blades are stopped. One way to do that would be to power them from the grid instead of from the turbine. If those things are grid powered, then a wind turbine might actually very very very slightly raise local atmospheric temperature. Anyone here happen to know if they actually do power anything in the turbine from the grid, or if they do something else like power such things from batteries that get recharged by the turbine when it is generating power?

kergonath 5y ago

That's bullshit. They can plausibly cause some surprising changes by disturbing the local air circulation patterns (which can either increase or decrease temperatures at a very local level), but increasing the temperature because of friction is a fantasy. If this were happening at a significant scale, it would decrease atmospheric temperatures, because the energy that ends up heating the blades would have to come from somewhere, and the air would lose some of its kinetic energy.