some ongoing progress in renewables

-in solar:

http://phys.org/news/2016-01-cheaper-solar-cells-percent-efficiency.html

-and wind:

http://phys.org/news/2016-01-denmark-energy-world.html#nRlv

-and here is yet more hard evidence to upset the man made global warming deniers:

http://phys.org/news/2016-01-man-made-oceans.html

Originally posted by humy
-and here is yet more hard evidence to upset the man made global warming deniers:

Global warming deniers, like creationists, never let evidence get in their way.

If you really want to upset them, mention a carbon tax.

Originally posted by humy
-and wind:

I have in the last few years been surprised by wind. It is now the cheapest source of energy bar none and set to be on of the largest renewable sources for many countries.

Originally posted by twhitehead
I have in the last few years been surprised by wind. It is now the cheapest source of energy bar none and set to be on of the largest renewable sources for many countries.

Is there a maximum you can draw energy from wind? Like, if you somehow technologically drew out 100% of the available wind power, would that effect the climate and if so, what level of energy extraction would put us over some cliff where we get unwanted changes in climate?

Originally posted by sonhouse
Is there a maximum you can draw energy from wind? Like, if you somehow technologically drew out 100% of the available wind power, would that effect the climate and if so, what level of energy extraction would put us over some cliff where we get unwanted changes in climate?

There is a maximum you can physically draw from wind in any given area. The wind downwind of a windfarm is significantly reduced.
How this affects the climate will vary from location to location. It has been argued on this forum in the past that we should deliberately erect wind farms in order to reduce the damaging effect of hurricanes. They may also help with tornadoes - a major hazard in the US.
I am sure there are some locations where it would be undesirable such as when the wind brings the rain or has a desirable cooling / warming effect between the land and ocean.

Overall, however, we can comfortably extract enough wind to power human civilization without destroying the climate, and if we pick and choose the locations wisely we can actually get significant benefits overall.

Originally posted by sonhouse
Is there a maximum you can draw energy from wind? Like, if you somehow technologically drew out 100% of the available wind power, would that effect the climate and if so, what level of energy extraction would put us over some cliff where we get unwanted changes in climate?

Globally, the current amount of kinetic energy taken out of wind power is massively totally dwarfed by that from trees, forests, sea waves, hills, mountains and buildings. So I think we could increase our current amount of wind power by something like at least 100 fold and we will still see only insignificant global climate effects from that.

Originally posted by humy
Globally, the current amount of kinetic energy taken out of wind power is massively totally dwarfed by that from trees, forests, sea waves, hills, mountains and buildings. So I think we could increase our current amount of wind power by something like at least 100 fold and we will still see only insignificant global climate effects from that.

That sounds logical. Wiki says the world as a whole is getting about 4% of it's total energy from wind, so it doesn't need to be 100X more, only 25X more and you are at 100%. Of course that won't happen but you can see putting up say 10X more turbines you would be up to 40% like Denmark. That would be significant.

Originally posted by humy
Globally, the current amount of kinetic energy taken out of wind power is massively totally dwarfed by that from trees, forests, sea waves, hills, mountains and buildings. So I think we could increase our current amount of wind power by something like at least 100 fold and we will still see only insignificant global climate effects from that.

It must be noted that mountains in particular have a significant effect on rainfall. I am less sure about what effects they have on the wind. In central Africa much of the rainfall comes from converging winds of hot and cold air. If the wind speeds were reduced this might have an effect on rainfall, I do not know. It would probably have some effect on where the rainfall took place, but that could be a good thing if done right.

Originally posted by twhitehead
It must be noted that mountains in particular have a significant effect on rainfall. I am less sure about what effects they have on the wind. In central Africa much of the rainfall comes from converging winds of hot and cold air. If the wind speeds were reduced this might have an effect on rainfall, I do not know. It would probably have some effect on where the rainfall took place, but that could be a good thing if done right.

So the question is how much energy in total is there in wind and how much would extracting 100% of our current needs, what would be that ratio? 1-1? Probably not.
1:1000? That is to say, even if we sucked up all the energy our civilization needs, there is a thousand times more in wind? 100 to 1? Any estimates?

I would think even if we extracted 1 percent and that represented our total usage of energy, there would not be much effect on the world.

But the numbers need to be run. Probably already has been somewhere.

Originally posted by sonhouse
That is to say, even if we sucked up all the energy our civilization needs, there is a thousand times more in wind?

Considerably more than 1000:1

But the numbers need to be run.
No, actually, they don't. We know there is more than enough wind without bothering running any numbers.
Denmark managed to get half its power from wind with no ill effects. If they were anywhere close to the limit we would know about it.

Probably already has been somewhere.
I am sure some calculations have been made for various types of wind power, but given the wide variety I doubt there are anything more than wild estimates for global availability.
Remember that the higher you go the more wind there is, so any such calculation must make a decision as to how tall your wind turbines are. And what about other types of wind generators such as flying ones?
And do you include all the worlds winds, open ocean and all, or just the most viable locations?
For example I bet a tiny area on Antarctica could supply all the worlds needs, but its not exactly practical.

With that said:

Abstract: The potential of wind power as a global source of electricity is assessed using winds derived through assimilation of data from a variety of meteorological sources. The analysis indicates that a network of land‐based 2.5 MW turbines restricted to non‐forested, ice‐free, non‐urban areas operating at as little as 20% of their rated capacity, could supply more than 40 times current worldwide consumption of electricity, more than 5 times    total global use of energy in all forms. Resources in the contiguous US, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the US.  Estimates are given also for quantities of electricity that could be obtained using a network of 3.6 MW turbines deployed in ocean waters with depths less than 200 m within 50 nm of closest coastlines

https://dash.harvard.edu/bitstream/handle/1/5029362/Lu_Wind_PNAS.pdf

Originally posted by twhitehead
Considerably more than 1000:1

[b]But the numbers need to be run.
No, actually, they don't. We know there is more than enough wind without bothering running any numbers.
Denmark managed to get half its power from wind with no ill effects. If they were anywhere close to the limit we would know about it.

Probably already has been somewhere.[/ ...[text shortened]... osest coastlines[/quote]

https://dash.harvard.edu/bitstream/handle/1/5029362/Lu_Wind_PNAS.pdf

They have to be with in 50 nanometers of the coastline?🙂

http://phys.org/news/2016-01-enormous-blades-offshore-energy.html
"...
Sandia’s 100-meter blade is the basis for the Segmented Ultralight Morphing Rotor (SUMR), a new low-cost offshore 50-MW wind turbine. At dangerous wind speeds, the blades are stowed and aligned with the wind direction, reducing the risk of damage. At lower wind speeds, the blades spread out more to maximize energy production.

...The exascale turbines would be sited downwind, unlike conventional turbines that are configured with the rotor blades upwind of the tower. ..."

-I am impressed.