PowerSwitch

http://www.energybulletin.net/stories/2 ... -gigawatts

Through the clouds of wishful thinking that too often make up what we are pleased to call a collective conversation on the subject of energy, a ray of common sense occasionally shines through. This week’s ray came by way of a study on the Earth’s thermodynamic balance, soon to be released in no less a scientific publication than the Proceedings of the Royal Society. The study found among other things that there’s a fairly modest upper limit to the amount of energy that wind farms can extract from the atmosphere without changing the climate.

So far, at least, the peak oil blogosphere hasn’t responded to this study at all. That’s not surprising, since the idea that renewable energy resources might also be subject to environmental limits is about as welcome in most alternative circles these days as a slug in a garden salad. These days, for many people who consider themselves environmentally conscious, a vision of giant wind turbines in serried ranks as far as the eye can see fills a pivotal emotional need; it allows them to pretend, at least to themselves, that it’s possible to support today’s extravagant lifestyles on renewable energy – to have our planet, one might say, and eat it too.

There are a number of limits to the spread of renewables (in their current form), this is just one of them.

Before jumping to conclusions one should follow the linky tree, via the archdruid to New Scientist http://www.newscientist.com/article/mg2 ... print=true , Cornell http://arxiv.org/abs/1103.2014 and the Kleidon paper, http://arxiv.org/format/1103.2014


Planting a forest, having the wind energy converted to heat via bending tree trunks back and forth, has a bigger effect, what with there being a lot of trees in a forest.

Interesting..

I often wondered about the mechanics of extracting power from the wind..

With enough wind turbines taking power out of the wind, what actually happens to the now power depleated wind?

Also we know apparantly that wind energy can be converted to electrical or mechanical power..wind turbine/windmill.

But energy use creates heat in most cases..I.E. boiling a kettle, toaster/microwave/tv light bulb, electrical motor etc...

I suppose super cooled motors might be different but how do you create the super coling coolant without creating heat?

The study mentioned above seem to say that taking so much energy out of the wind to make power thats use releases heat means that it would heat the earth just as much as Co2 production from fossil fuels...

I often wonder about things like cars..each one producing far more heat than a 5 bar electric fire.. all those 5 bar electric heaters travelling up and down the roads, or sitting still..even if 100% clean burning, the heat is still released...

So tell me this.. A large sailing ship.. blown along by the wind is taking energy out of the wind in the same way a wind turbine does yes?
A fuel oil or gas turbine powered ship creates heat from combustion of the fuel YES?

But where is the heat from a sailing ship ? Do sails get "hot".. they certainly dont produce a form of power that seems to produce heat, not like a wind turbine that generates electricity via a gear set and generator.. where the produced electrical power creates heat in transmission and often in it's end use...

Is the energy taken from the wind by a sailing ship turned into heat by the friction of water agains the hull as it moves through it?

Is direct mechanical power produced by a windmill far better than electrical power produced by a wind turbine?

If so then bring back windmills and wind pumps and wind hammers...
Tap the energy supply of rivers and waves and make sailing ships again with motors only for harbour manouvering...

Use wind turbines at sea to make fresh water from sea water along the african coast and irregate new rain forrests..

Pie in the sky you think.. well just as much as a realistic grid connected wind farm network that would actually save any Co2 in the long run...

Is the energy taken from the wind by a sailing ship turned into heat by the friction of water agains the hull as it moves through it?

That's the one. Exactly so. All kinetic energy in the air (wind) ends up as thermal energy (heat). Some goes to the fish, some to the squirrels some to your tea pot. Eventually it all, every last joule of it, radiates off into outer space, spreading to infinity, towards the ultimate heat death of the universe. Our wind turbines just divert a little bit of the energy for a short time for our convenience.

Glow Worm wrote:Use wind turbines at sea to make fresh water from sea water along the african coast and irregate new rain forrests..

Sounds like a very good idea indeed: use windmills to produce desalinised water rather than electricity.

The end product is immensely useful and desperately needed in the south and east of the UK, and the idea avoids trying to integrate variable, intermittent, non-despatchable wind power into a sophisticated, island grid.

The large scale desalination of sea water is an excellent use for renewable energy.
There two main ways of removing salt from sea water, evaporation and reverse osmosis.
Evaporation needs a lot of heat, which is easily obtained from solar thermal sources. This is low technology and the plant may be built with basic building skills and fairly basic materials. For extremely small scale use the sea water may be fetched in buckets, though pumps are better, preferably PV powered.
Reverse osmosis needs a lot of electricity* which may be obtained from wind turbines. Manufacture and maintenance involves a lot of high technology.
*In theory, other sources of mechanical power such as direct drive from a wind turbine or an engine could be used, but in practice electric power is normally used. Very small units used in lifeboats are hand powered.