Criticism of the current electricity market, inconsistency and prospective for renewable energies

[SebastianL]

[Remundo]

in any case Sébastien is starting to admit that his storage/removal of electricity efficiency is around 50%

Which is very optimistic, but not absurd.

after having GWh stored at X00°C with I don't know what coolants (he was talking about molten zinc), you have to see the stuff and the losses....

[SebastianL]

in any case Sébastien is starting to admit that his storage/removal of electricity efficiency is around 50%

Which is very optimistic, but not absurd.

after having GWh stored at X00°C with I don't know what coolants (he was talking about molten zinc), you have to see the stuff and the losses....

I only admit a little, I will wait to have a specialist opinion able to calculate the maximum performance at 500°c 78bar (epr), technologically possible.
When we do the rankine cycle 220bar at 620°C, the calculator gives 44.5% the Germans do 47.5%, the road is not so clear.

There are no losses for the transport of vaporized zinc to liquid zinc in the superheater, theoretically we could even turbine from 1400°c to 600°c (I'll save you on this one). Any thermal losses from the tank are recycled from 285°c to 500°c, i.e. half if the final efficiency is 50%

[sicetaitsimple]

after having GWh stored at X00°C with I don't know what coolants (he was talking about molten zinc), you have to see the stuff and the losses....

As I said a bit above, I wasn't interested in the storage technology, I assumed that it could actually superheat steam from 286°C to 500°C whatever the load of the plant, in all my posts.
It's definitely a bit more complicated in real life...

[SebastianL]

I also have a hard time admitting that we do not find the improvement in the ratio of the 2 Carnot yields at temperatures of 285°c and 500°c.
We have a fixed auxiliary energy cost, proportional entropic losses, I admit I have no answer on this subject, I must have missed an episode with entropy

[sicetaitsimple]

I only admit a little, I will wait to have a specialist opinion able to calculate the maximum performance at 500°c 78bar (epr), technologically possible.

I wrote it to you on page 8: "" It's a steam turbine superheated to 500°C, whose cycle efficiency must be at the wet finger of 36 to 37%."
You have the right to doubt it, but you have to look for counterexamples....

[Remundo]

but still, why do you want to store in boiled zinc?

It's a pretty dangerous thing... in terms of industrial risks, good luck.

should rather see a solid-liquid transition with a metal with the right temperature, and under atmospheric pressure.

And still there will be plenty to do. A huge boiling liquid zinc, it radiates cheerfully and it loses a lot of conductoconvective...

We're talking in GWh here...

in comparison with turbine-pumping techniques that produce 80% efficiency, that leaves me wondering.

People will retort that we don't have the terrestrial sites to do enough. In my opinion on this subject, we must consider WWTPs at sea/ocean.

[SebastianL]

but still, why do you want to store in boiled zinc?

It's a pretty dangerous thing... in terms of industrial risks, good luck.

should rather see a solid-liquid transition with a metal with the right temperature, and under atmospheric pressure.

And still there will be plenty to do. A huge boiling liquid zinc, it radiates cheerfully and it loses a lot of conductoconvective...

We're talking in GWh here...

in comparison with turbine-pumping techniques that produce 80% efficiency, that leaves me wondering.

People will retort that we don't have the terrestrial sites to do enough. In my opinion on this subject, we must consider WWTPs at sea/ocean.

Zinc is just molten metal which evaporates at 920°C and which will condense further, the thermal flow is regulated by the return of condensate. It's low pressure.

I am happy to follow you on the STEPs at sea, even if I do not know the costs.

I would still like to deviate from the precise nature of this auxiliary overheating.
We read for a Rankine cycle 2→3: Isobaric and irreversible vaporization.

I would like to check if the choice of Rankine hirn (thus with overheating) is justified only for technical aspects of the turbine or if theoretically it is better than classic rankine.
Because if it is theoretically better, that means that we have a hot source which allows xBar of pressure but that we choose to have more entropy with a lower pressure. that would mean that the overheating as such has a positive effect and that would mean that the rankine calculation models applied to my gadget, could not take into account that I do not sacrifice the pressure to have a higher temperature at equal hot spring temperature!
In short, check that Rankine 2→3: Isobaric and irreversible vaporization applies flawlessly with auxiliary overheating.

[Remundo]

From memory, the Hirn cycle in terms of yield (useful work/costly heat) is worse than that of Rankine.

But it has other advantages: it dries out the steam at the end of expansion (which otherwise liquefies), and in gross power, it increases the production of the plant. It is therefore a technical compromise.

isobaric heatings always deviate from the Carnot efficiency. The longer isobaric transitions, the further away from the Carnot cycle (2 isothermal and 2 adiabatic). But technically isobaric heat transfers are simpler.

The only cycles that affect the yield of Carnot are the Stirling cycles and their variants: they rely on 2 isotherms, connected by isochores (Stirling cycle) or isobars (Ericsson cycle)

it is still necessary to provide for the recycling of heat transfers (role of regenerators).

In practice, all REAL cycles, due to losses and irreversibilities, have a yield lower than the theoretical predictions.

The Carnot cycle, theoretically the purest and most elegant, is in fact not used by any machine. Even the Stirling and Ericsson Cycles are abandoned (although they have demonstrated their feasibility and effectiveness). In the steam turbine industry, we do Rankine-Hirn; in the gas turbine, Brayton-Joule; in Diesel or Otto engines.

Raw power is favored, often to the detriment of thermodynamic efficiency.

[SebastianL]

I did a little tour of entropy in the physical sense of the molecule, and indeed it's a fundamental relationship between temperature and pressure, it's not a story of misinterpreted vapor tables to my exotic thingy!

I still have trouble understanding, how adding thermal energy to a vapor molecule increases its molecular entropy.
In my opinion we concentrate the energy in the water molecule but it is not the reality, remains to know why!

At first glance when looking at this steam couple:

773K 70bar 48L/kg 20.765kg/m3
558k 70bar 27L/kg 36kg/m3

The deal looks good giving 18.7% energy for a 77% volume boost but for a curious matter of entropy, in fact no!
I got entropy