What PV surface for the world's energy?

[Grelinette]

I often hear this question and the answers given are very different.

I found this site which addresses the question and gives an argued answer:

"to meet global energy needs: being located in France, 1 km² is needed, that is to say that it would practically be necessary to cover twice the surface of mainland France to supply the planet. Placed at the heart of the Sahara, it takes only 050 km², which is roughly the surface of Somalia. "

Or a large rectangle of 1000 km by 636 km would be enough! ...

source: http://www.ddmagazine.com/314-combien-p ... monde.html

It's very theoretical but fun.

[Grelinette]

I add after reading the comments on the link site, that making a large area of ​​a block in one place is not the most effective because the sun is turning.

A PV belt which follows the equator would therefore be more effective, but as another comment points out, a PV in a hot place loses its efficiency!

Not to mention the effect of the seasons which changes the angle of the sun's rays.

Oulala, not easy this question !!!

But it is a good question what the ideal PV surface would look like to optimize the production of energy for global human activities (simply 'necessary and sufficient') from the sun !!!!

[Obamot]

Bof, bof, photovoltaic panels to cover the "full-need"is that reasonable !?

And what, all types of energy combined? On the contrary, it is simple to answer.

For what is called the "FULL NEED"
If yes, why 636 km² when 000 would be enough for thermal solar energy? This would multiply by six the risks due to the problems of geopolitical instability, much longer distances to travel, multiply by six the environmental footprint ... also multiply by six a possible royalty to the states for the occupation of land, and their corollary the cost of operation, costs of use, maintenance and cleaning of the panels higher ... I think it is impracticable for this last point, there is no water in the deserts available to clean them! While thermal solar is efficient enough to desalinate seawater and route it by penstocks ... And after that be used for watering plantations! Even even make deserts bloom again with factories which would advance at the rate of the advance of the new vegetation ... (Let's be crazy!)

Furthermore, if we want to do things well, we need power stations that are distributed in latitude to make a belt of power stations to cover the day / night cycles without interruption!

And that is not possible with PV farms, which can only operate at full capacity for a few hours a day, while solar thermal can store heat in the ground (in the form of salts or molten silica, even concrete blocks) and allows an almost uninterrupted cycle of electricity production. whereas there is no efficient "economical" and high efficiency storage for PV electricity in the current state.

PS: I saw that you had completed, the equator is located far too south for Europe, at latitude 30 ° North it is perfect (North Africa) the sunshine is ideal. Solar thermal eventually, but for PV it's niet. On the other hand, we should not think in terms of a single supply, of a single type of production, but of an energy supply mix! So the "FULL NEED" is very theoretical, and will never be provided by a single source!

[dede2002]

Hello

I think the calculation is wrong, because "full need" represents the consumption of a wealthy minority.

If we redo the calculation in relation to the world population, because there is no reason that the south has less than the north (especially if production is "delocalized" to the south), the result will differ significantly ... ?

[Ahmed]

Dede, your remark is very relevant (and I am happy that it can make someone else react!) and the way in which this school exercise is treated is profoundly revealing of the conservatism which governs our societies, which augurs ill for its ability to overcome contradictions other than from a symbolic angle, another way of denying reality ...

[dede2002]

Basically, the full-need cited is "the production of energy for global human activities (simply" necessary and sufficient) ".

Currently, by dividing consumption by the number of inhabitants, 1/3 or even 1/4 of the world population consumes more than the average, and 2/3 or even 3/4 is below the average.
For example, a Frenchman consumes 3 times more than the world average, a Malagasy 4 times less. *

* this is only an average per country, within each country there are also big individual differences.

We must therefore review the basic equation ...

[Ahmed]

"We must therefore review the basic equation ...", except that what is "necessary and sufficient" is not more negotiable than "the standard of living of Americans" (dixit Bush).
A decrease in our level of comfort which would result from greater equity, a prerequisite for an improvement in the lot of the greatest number, is utopian; this troublesome contradiction has long been circumvented thanks to the conceptual sleight of hand of "development".

[Grelinette]

Your comments appeal to me because they make me review this question from another angle.

Indeed, when we talk about the amount of energy that the species consumes around the world, we completely hide the fact that this consumption is completely unbalanced.

Evaluating this quantity therefore does not make sense, and, more serious, denotes, as Dédé and Ahmed underline, of a reflex that we have (and that I have) to accept or more exactly to turn a blind eye to the human injustices and inequalities in terms of energy consumption.

We must therefore review the basic equation ...

Important parameters are missing, the first one being assess the amount of energy needed, sufficient (and reasonable) for each country, each population, to get the global human need ... reasonable.

[Ahmed]

Your last question, Grelinette does not include a possible answer until the criteria for what is really necessary are defined; however, what is "necessary" essentially stems from a social need, which is a subjective notion and not necessarily quantifiable ...

If we are content to choose the current criteria (therefore, in a given system), the minimum "needs" applied to each member of the human species result in a physical impossibility *: our system is intrinsically unequal ...

The concepts of "underdeveloped countries", then of "developing countries" are formatted to camouflage the predation of the countries enriched at their expense: if we follow what these names suggest, they would be countries destined for us join, as long as they apply to imitate our approach. This is obviously absurd, since they do not have countries to the detriment of which to "develop"!

* It goes without saying that I am not only considering energy, but also the use that is made of it.

[dede2002]

We also talk about "emerging countries", it reminds me of someone who tries to get his head out of the water so as not to drown, but the "rescuer" reaches out to him and pushes him back with his foot ...

As Ahmed points out, a reduction in the level of comfort (and waste) of the wealthy is utopian.
On the other hand, an increase in the level of comfort of the great majority seems legitimate, in "emerging countries" people dream of beautiful villas and big cars that they see in pictures (and in the street ...), or simply to have a fridge and electric lights ...

To further distort the equation, to the energy consumption of rich countries must be added the import of gray energy never counted, or rather which is counted in the consumption of the producer "emerging countries". (ex: beans, cotton, fertilizers, mines, manufactured products, etc.)