OT sun and wind question

Well, solar panels over the sea stop sunlight hitting it, preventing photosynthesis and warming so certainly have a local effect. The wind question is meaningless. If you cram enough windmills close enough together they will interfere with each other and not be very efficient, but wind would still blow over the top of them, like it does over a forest, for example. I suppose if you built windmills all the way up to the stratosphere you could significantly affect atmospheric circulation as you would, for that matter, if you covered the planet with housing with its roof at around 10 km.

I think someone calculated the sum of tidal solar and wind energy and declared that if populatoin growth continued at its current rate, there wouldn't be enough renewable energy in the whole world to keep them alive beyond 2150 or so.

The earth receives more solar energy every hour than the human race consumes from all its sources (primarily fossil fuels) in a year. Nothing we can possibly do to tap into that source of power at our current level of technology or energy use requirement can make more than a miniscule blip on the general course of life on earth.

Total wind energy is only a tiny fraction of total solar energy, which drives it of course, but again we can't extract enough of it to make any real difference to the climate. We might manage to slightly slow the average wind speed at turbine height near ground level if we installed enough wind turbines but that wouldn't make a jot of difference to the wind energy at higher altitudes like the jet stream where it can be hundreds of mph.

JOOI and I'm sure we covered this before;!. Where does all the heat we use and waste go to over time seeing that energy cannot be destroyed ?.

This just heating up the earth which now seems to be debunked or does it just radiate off into space as Infra Red radiation and thats well, that?....

And then, we can start to build a Dyson Sphere :)

If you cover a field with PV, you can't grow crops there - it does obviously make a difference to photosynthesis in the shadow. But the effect is limited to the shadow. And if you've got it on somewhere you're not trying to grow stuff (buildings, etc), there's no difference.

With wind, yes, it's finite, but that finite number is way bigger than you can hope to affect with some piddly turbines - and even the biggest ones people are putting in now are piddly compared to the size of the atmosphere. So yes, in practice there's enough to not worry about using it up.

By a considerable margin:

I'm guessing that a similar question but on tidal power might have a different answer. It seem plausible that extracting enough energy from the tide could bring it to a standstill.

Good thing I read the whole thread - I was about to reply with that suggestion.

Don't the tides get two new boosts of energy every day as the earth spins with respect to the moon?

As the population of greens increases the speed of rotation of the earth slows down. Eventually tides stop. One side of the earth becomes a desert, the other side becomes icy cold. Global warming and cooling.

Simple answer, no we couldn't use it all, not without changing the climate and the environment. In fact if you believe the met offices claim that we have changed the global temps by 0.2% so far then using more than 0.2% of the energy is bound to have an effect on climate of at least as much. You would be moving energy from large areas and putting it into localised hotspots and that already affects the climate when you are just adding energy to the hotspot, taking it from elsewhere must be worse.

I wouldn't rely on that being true. If you stop the wind lower down then there will be less evaporation and less mixing of water vapour in the atmosphere, it would have significant climate change effects.

It does but, if you extract all the energy from the tides it will affect the environment. The energy currently does something to the natural environment and removing it cannot have zero effect. Silting of estuaries and the susequent floods would be one effect. There are going to be many that nobody has thought about yet.

You'd be extracting energy from the spin of the earth. Of course, the tides already do this and the energy is dissipated as heat. So the earth spins slightly more slowly as time passes and the day gets longer. And also in consequence the moon orbits further from the earth

Apparently when the earth/moon system first formed and there was first free water on earth, the tides were some km high.

In the long run when the moon moves far enough away, its gravity will no longer be enough to keep earth's spin axis stable, and it could tip over chaotically due to the gravitational influence of the giant planets.

Mind you, could be that the sun will have gone red giant by that time, so earth surface temps will be some hundred of degrees.

I wonder if scotty will get marooned on it.

well exactly.

depends how large the area is, have you ever been out when an eclipse occurs, the one is 1998 or was it 99 the brids stopped singing and tehre was a a errie silence so it might just not be crops that are affected y lack of light.

Wind is a starnge one as it;'s prioduced by changes in heat to if you have massive solar panles perhaps in orbit that could well change the amount and direction of winds.

It's very obvious that animal life is effected by lack of light - try walking anywhere with your eyes shut for an example.

But if you've removed the vegetation from a field for a PV array, you'll also get rid of pretty much all the animal life. There will still be a bit of light leaking through to see by, so it won't all go, but it'll be similar to building a big car park.