Questions about "renewable" energies

[Chuwee]

A small question,

By definition, renewable energies are those given by our planet or external elements.

With the basic principles of mechanics such as conservation of momentum, etc., if all of the energy needed on the planet comes from these energies, it would not affect temperature, strength and wind speed, etc?

[Cuicui]

A small question,
By definition, renewable energies are those given by our planet or external elements.
With the basic principles of mechanics such as conservation of momentum, etc., if all of the energy needed on the planet comes from these energies, it would not affect temperature, strength and wind speed, etc?

Earth's renewable energies come from the sun. They are mainly stored in biomass and in the transformation of liquid water into water vapor. Does the fact of capturing or not these energies modify the energy balance and the climate? This seems unlikely, given their insignificant level in comparison with the enormous amount of energy brought directly by solar radiation (1 kWh per m2). The problem lies rather in the combustion of fossil fuels, increasing the rate of CO2 that the biomass cannot store as it goes, hence the increase in the greenhouse effect.

[Chuwee]

As it stands, of course, it is fossil fuels that are penalizing us.



In 50 years, in a perfect world :

Based on your data, with an annual global consumption of the order of 2e12 Wh (roughly, 5x more than at present) and admitting that all the energy comes from solar it still makes 2e9 m² of solar panels, or 1 / 255th of the surface of the planet and again, with a yield of 100% and operating 24/24 (at night, it will be hard) !!!
It is as much energy which will be "lost" for the planet.
It will surprise me that it has no impact on our environment ...

[Christophe]

Chewee are you talking about electrical energy I guess? So photovoltaic panels with a yield of 10 to 15% is that right?

[Chuwee]

Indeed, I am talking about electrical energy, assuming that all the energy of the planet is consumed in this form and produced with cells with a yield of 100% (and not 10-15%) and an illumination of 24 hours by day.

In fact, this is just an example. We could sound the same way with wind turbines, etc.

It is not really our mode of energy production that is deplorable but our consumption. Even by producing the "cleanest" energy possible, therefore without CO2 emissions, etc., we are going straight into the wall ...

[Woodcutter]

[...] With the basic principles of mechanics like the conservation of the quantity of movement, etc, if the totality of the energy necessary on the planet come from these energies, it would not have there an incidence on the temperature, force and speed of winds, etc?

If, surely, but how to quantify it?

[Chuwee]

Quick calculation, I don't know if it's fair ...


With a maximum output, the wind speed at the exit of a wind turbine and 3x lower than that at entry.

For a 1MW wind turbine with a mechanical efficiency of 80%:

Energy to be supplied per second: 1e6 / 0.8 = 1.25e6 J
theoretical maximum efficiency of a wind turbine: 59.3%
The wind must therefore be a kinetic energy of 2.1e6 J
The wind energy loss is therefore 8.5e5 J ...

[Christophe]

Ok so some small remarks / suggestions regarding your calculations:

I think (I hope) that in 2050:

- there will no longer be an organized energy waste of the Vivrelec style systematically mounted (or almost) on all NEW apartments ...

- the technology of the panels and heating system will have largely evolved, as well as the standards of insulation ...

- people will have become aware of the "ENERGY PROBLEM" and will have adapted their behavior ... the x5 would therefore be highly overestimated

- cheap and highly energy-consuming Chinese products will no longer exist

The wind energy loss is therefore 8.5e5 J ...

Exact I had already asked myself the question but ... in my opinion (without just calculation by intuition) frankly negligible compared to the global power of the winds ...

Even if we have billions of wind turbines, the phenomenon would only be "negligible" compared to the winds (roughly we increase the average roughness of the ground and therefore the thickness of the boundary layer ...) especially those on average and high altitude which "make the climate"

You want to be sure: Are there studies on local climate change linked to the cutting down (or rather the growth) of forests?

[abyssin3]

Are there studies on local climate change linked to the cutting down (or rather the growth) of forests?

I do not have an example in mind, but in my opinion it is very likely, provided that the said forest is large enough (Ex Amazon).

Some may have already been seen on large forests or in the mountains after a great summer downpour of water vapor escaping high up. It shows that the very close air and the forest are linked.
As for higher altitude, I imagine that gas exchanges (CO² / O²) still have an impact. It also seems to me that ULMs and gliders are looking for wooded areas to gain altitude because there is an updraft, so hot air, so impact on the local climate.
And in general, any home of life has an impact on its environment, Ex: anthill, large agglomerations (gray cloud over Paris) in terms of animal life, so this must also be the case for plant life (which also includes a whole fauna). Without forgetting that it is from bacterial life that the climate of the whole Earth became habitable millions of years ago.
And when we see (Ex: Aral Sea) how the local environment can be sensitive, the idea that a forest influences its local climate seems almost certain to me ...But still no example
It also shows that we have long underestimated the effects that we could inflict on the environment: we have long thought that the sea was too big to be polluted one day, that the aral sea was too big so that we can dry it out, and we can always cut as many trees as we want in the Amazon, there are so many because we would never see the end of it. So many very false ideas.

[Cuicui]

It is as much energy which will be "lost" for the planet.
It will surprise me that it has no impact on our environment ...

I do not understand. No matter how much solar energy is collected, using it for work or heating will produce heat that returns to the planet. Where is the problem ?
On the other hand, nuclear energy produces energy in addition to solar energy. But the quantity is so low in proposal that it probably does not have a big impact.