5 ms·

Given that wind turbines are universally(?) white, I've always assumed it is to minimize heat absorption. If so, painting 1/3 of the blades black would increase

by driggs 4y ago

Given that wind turbines are universally(?) white, I've always assumed it is to minimize heat absorption. If so, painting 1/3 of the blades black would increase heating of the painted blade, especially in lower latitudes (this study was done at high latitude in Norway). What's the side effect? Also, this strategy will obviously have zero impact on bat deaths, given that a white blade and a black blade are identical to echolocation at night. Curtailment of turbines in low wind condition - which is when bats are able to fly, and when turbines produce the least amount of energy - is the proven way to minimize bat deaths. But wind farms want to maximize energy production (profit), so are not fond of curtailment as a strategy.

actually_a_dog 4y ago
A lot of things are painted white because titanium dioxide is a super cheap, white pigment.
- exmadscientist 4y ago
  Is carbon black not a super cheap, black pigment?
  - samatman 4y ago
    A lot of things are painted black as well.
daniel-cussen 4y ago
Echo-reflective surfaces. Plus I agree bats have worth, but these guys carry crazy amounts of diseases like cough cough Covid-19 cough.
- unethical_ban 4y ago
  Not really, and they are great pest control. In South Texas we have bat colonies under freeway overpasses, and trust me, bats are not a source of disease concern here beyond "don't mess with them even if injured".
- o_1 4y ago
  Oh i forgot we blamed rats for the plague too, bats definitely caused covid we can't be wrong twice.
- driggs 4y ago
  No, bats do NOT carry Covid-19. We were actually prevented by the USFWS from performing winter hibernacula counts for fear that we humans might spread Covid to bats, whose immune system practically shuts down during hibernation, until it was determined that this isn't possible. Besides, the bats which are primarily killed by wind turbines are not cave-roosting bats, but high-flying tree bats. Bats either have a strategy of hibernation or migration, and it is these larger migratory tree bats which fall prey to turbines. Echo-reflective surfaces wouldn't make a difference. Bats aren't killed by colliding with turbine blades, they are killed by barotrauma when flying NEAR the high-velocity low-pressure turbine blades when they try to investigate the large, moving, novel objects. I repeat, the most effective way to prevent bat deaths at wind farms is to curtail (brake) turbine blades during low-wind conditions; a 25-gram bat doesn't fly in high winds, and turbines are least efficient in low winds. Source: I perform bat echolocation surveys, including on wind farm sites.
  - solardev 4y ago
    Is there something special about bats that make them immune to covid-19? Why can't they carry it the way that deer, cats, etc. can?
    - driggs 4y ago
      Disclaimer: This is out of my area of expertise. Bats, in general, are susceptible to coronaviruses, in general, as are all mammals. But not all mammals are susceptible to all coronaviruses. The disease Covid-19 is caused by the specific coronavirus SARS-CoV-2, and that specific mutated virus only affects certain mammals, notably humans. It is apparently contagious to some other mammals, including deer, cats, minks, but not contagious to some other mammals. I have read that coronaviruses similar to SARS-CoV-2 have been found in Horseshoe Bats in Asia (note: there are no Horseshoe Bats in North America), but that do not have a binding protein which would allow them to infect humans; I believe the opposite is true of SARS-CoV-2, it binds to a human receptor but not to bats'. It is hypothesized that SARS-CoV-2 may have mutated from a bat-borne coronavirus, but several intermediate links between species must have been involved (Pangolins?), and it is perhaps this chain of binding mutations responsible for this difference in hosts. Though we no longer handle bats with bare hands these days (to protect bats from us!), this was common practice for decades. Other than rabies (which can be spread by any mammal, and occurs in bats in no higher percentage than in skunks, foxes, etc), I'm not aware of any known disease which can be spread from North American or European microbats to humans. I don't have specific knowledge about megabats (fruit bats) or Asian or African species.
upofadown 4y ago
The blades are made of composite materials that involve some sort of epoxy binder. So heat would be important to avoid. Composite aircraft are white for that reason.
Smoosh 4y ago
Here in Australia, kangaroos colliding with cars are a problem. Wind powered "whistles" are available which claim to ward off the kangaroos (eg https://www.motoquipe.com.au/buy/animal-repeller-black-sonic-whistle-shuroo-shoo-ro/3084 https://www.motoquipe.com.au/buy/animal-repeller-black-sonic...). I wonder if something similar would work for bats (and maybe birds too)? But then again I'm dubious about their efficacy for kangaroos. It would be worth investigating though.
- driggs 4y ago
  Ultrasonic deterrents have been experimented with, and have shown reduction in bat kills, but there are many challenges with respect to efficiency and reliability. Technically, ultrasound is attenuated significantly in the atmosphere, so it takes a lot of amplification to broadcast ultrasound significant distances. Not to mention that the bats are often flying with the wind, not against it, which means the ultrasonic transducers are projecting into the wind. Certain signals and sample playbacks might be effective for one bat species, say Hoary Bats, but not deter another species like Red Bats. Detecting bats' echolocation calls, however, is much easier. A brilliant researcher in Arcata CA has a working system installed in a commercial wind farm which detects the presence of migratory bats, and brakes the wind turbines until no bat calls have been detected for some some period of time. Bats don't fly all night, and migrating bats may travel together.
solardev 4y ago
Is that going to cause a rotational imbalance, like a radiometer? https://en.wikipedia.org/wiki/Radiometer https://en.wikipedia.org/wiki/Radiometer
- NavinF 4y ago
  Crookes radiometers only work in a partial vacuum. The effect is way too weak to measure at 1atm.
chaxor 4y ago
A better proposal might be to put solar cells (dark to absorb light) on the towers and blades. Dual power generation would be nice. Putting them on the coast could generate power from sun, tide, and wind.
- adrianN 4y ago
  Solar cells are pretty heavy.
- chriswarbo 4y ago
  Forming a reliable, low-maintenance electrical connection between the spinning blades and the tower seems difficult.
- NavinF 4y ago
  >I want to send kilowatts over slip rings You’re in for a world of hurt.

by driggs 4y ago

actually_a_dog 4y ago

A lot of things are painted white because titanium dioxide is a super cheap, white pigment.

exmadscientist 4y ago
Is carbon black not a super cheap, black pigment?
- samatman 4y ago
  A lot of things are painted black as well.

daniel-cussen 4y ago

Echo-reflective surfaces. Plus I agree bats have worth, but these guys carry crazy amounts of diseases like cough cough Covid-19 cough.

unethical_ban 4y ago
Not really, and they are great pest control. In South Texas we have bat colonies under freeway overpasses, and trust me, bats are not a source of disease concern here beyond "don't mess with them even if injured".
o_1 4y ago
Oh i forgot we blamed rats for the plague too, bats definitely caused covid we can't be wrong twice.
driggs 4y ago
No, bats do NOT carry Covid-19. We were actually prevented by the USFWS from performing winter hibernacula counts for fear that we humans might spread Covid to bats, whose immune system practically shuts down during hibernation, until it was determined that this isn't possible. Besides, the bats which are primarily killed by wind turbines are not cave-roosting bats, but high-flying tree bats. Bats either have a strategy of hibernation or migration, and it is these larger migratory tree bats which fall prey to turbines. Echo-reflective surfaces wouldn't make a difference. Bats aren't killed by colliding with turbine blades, they are killed by barotrauma when flying NEAR the high-velocity low-pressure turbine blades when they try to investigate the large, moving, novel objects. I repeat, the most effective way to prevent bat deaths at wind farms is to curtail (brake) turbine blades during low-wind conditions; a 25-gram bat doesn't fly in high winds, and turbines are least efficient in low winds. Source: I perform bat echolocation surveys, including on wind farm sites.
- solardev 4y ago
  Is there something special about bats that make them immune to covid-19? Why can't they carry it the way that deer, cats, etc. can?
  - driggs 4y ago
    Disclaimer: This is out of my area of expertise. Bats, in general, are susceptible to coronaviruses, in general, as are all mammals. But not all mammals are susceptible to all coronaviruses. The disease Covid-19 is caused by the specific coronavirus SARS-CoV-2, and that specific mutated virus only affects certain mammals, notably humans. It is apparently contagious to some other mammals, including deer, cats, minks, but not contagious to some other mammals. I have read that coronaviruses similar to SARS-CoV-2 have been found in Horseshoe Bats in Asia (note: there are no Horseshoe Bats in North America), but that do not have a binding protein which would allow them to infect humans; I believe the opposite is true of SARS-CoV-2, it binds to a human receptor but not to bats'. It is hypothesized that SARS-CoV-2 may have mutated from a bat-borne coronavirus, but several intermediate links between species must have been involved (Pangolins?), and it is perhaps this chain of binding mutations responsible for this difference in hosts. Though we no longer handle bats with bare hands these days (to protect bats from us!), this was common practice for decades. Other than rabies (which can be spread by any mammal, and occurs in bats in no higher percentage than in skunks, foxes, etc), I'm not aware of any known disease which can be spread from North American or European microbats to humans. I don't have specific knowledge about megabats (fruit bats) or Asian or African species.

upofadown 4y ago

The blades are made of composite materials that involve some sort of epoxy binder. So heat would be important to avoid. Composite aircraft are white for that reason.

Smoosh 4y ago

Here in Australia, kangaroos colliding with cars are a problem. Wind powered "whistles" are available which claim to ward off the kangaroos (eg https://www.motoquipe.com.au/buy/animal-repeller-black-sonic-whistle-shuroo-shoo-ro/3084 https://www.motoquipe.com.au/buy/animal-repeller-black-sonic...). I wonder if something similar would work for bats (and maybe birds too)? But then again I'm dubious about their efficacy for kangaroos. It would be worth investigating though.

driggs 4y ago
Ultrasonic deterrents have been experimented with, and have shown reduction in bat kills, but there are many challenges with respect to efficiency and reliability. Technically, ultrasound is attenuated significantly in the atmosphere, so it takes a lot of amplification to broadcast ultrasound significant distances. Not to mention that the bats are often flying with the wind, not against it, which means the ultrasonic transducers are projecting into the wind. Certain signals and sample playbacks might be effective for one bat species, say Hoary Bats, but not deter another species like Red Bats. Detecting bats' echolocation calls, however, is much easier. A brilliant researcher in Arcata CA has a working system installed in a commercial wind farm which detects the presence of migratory bats, and brakes the wind turbines until no bat calls have been detected for some some period of time. Bats don't fly all night, and migrating bats may travel together.

solardev 4y ago

Is that going to cause a rotational imbalance, like a radiometer? https://en.wikipedia.org/wiki/Radiometer https://en.wikipedia.org/wiki/Radiometer

NavinF 4y ago
Crookes radiometers only work in a partial vacuum. The effect is way too weak to measure at 1atm.

chaxor 4y ago

A better proposal might be to put solar cells (dark to absorb light) on the towers and blades. Dual power generation would be nice. Putting them on the coast could generate power from sun, tide, and wind.

adrianN 4y ago
Solar cells are pretty heavy.
chriswarbo 4y ago
Forming a reliable, low-maintenance electrical connection between the spinning blades and the tower seems difficult.
NavinF 4y ago
>I want to send kilowatts over slip rings You’re in for a world of hurt.