Energy storage gravity

[Meszigues3]

ah so ... fortunately the STEP exist and allow the equilibrium of the electrical network, with a very correct performance of restitution with respect to the pumping energy (around 80%) ...

The STEPs produced in France 5,8 TWh in 2016 on 500 TWh, ie around 1%; negligible.

[sicetaitsimple]

ah so ... fortunately the STEP exist and allow the equilibrium of the electrical network, with a very correct performance of restitution with respect to the pumping energy (around 80%) ...

The STEPs produced in France 5,8 TWh in 2016 on 500 TWh, ie around 1%; negligible.

Negligible in volume, certainly. I don't really know the installed power, a little less than 5GW? It would in this case (for 5,8TWh) about 1200h full power equivalent, which would still be not bad! In service rendered, at least.

This is the confusion that often exists when we talk about electricity storage. The value is the service rendered, not just the quantity that can be stored, which will necessarily be limited, unless you have infinite pockets.
And the more the quantity increases, the more the value decreases, message to those who would say "yaka do storage".

[Remundo]

ah so ... fortunately the STEP exist and allow the equilibrium of the electrical network, with a very correct performance of restitution with respect to the pumping energy (around 80%) ...

The STEPs produced in France 5,8 TWh in 2016 on 500 TWh, ie around 1%; negligible.

they are not designed to produce, but to store and return.

in absolute terms, a WWTP that does not have an altitude stream that feeds it consumes net energy.

[lilian07]

It is a shame that STEP is not more exploited to store the surplus energy from renewable energies. It could come very quickly with a good RE mix.

[sicetaitsimple]

It is a shame that STEP is not more exploited to store the surplus energy from renewable energies.

Ah there you can register for the competition for "the best sentence of the green business coffee"!

A STEP does not work according to the origin of the electrons, but according to the value (as a first approximation the market price) between the electricity which it must use to pump and that which it will restore by turbining, knowing that between the two there is a loss (in volume of MWh) of around 20%.

Whether it is nuclear, renewable energies, coal or gas, or even "fatal" hydroelectric power over the water does not change anything.

So the operation of a WWTP is not linked to the electricity mix, but to variations in market prices. Of course, a very "intermittent renewable" mix will occasionally cause strong variations.

[sicetaitsimple]

Complement: note that it has nothing to do (in terms of economic model) with an individual who would like to be equipped with batteries to store the solar electricity that he produces on his roof. In this case, he will save on his bill for transport and distribution costs, which can make his model interesting.

[chatelot16]

big difference between step and drums:

the step step turbine pumps have a very long lifespan, and do not depend very much on the number of kWh stored: it is therefore profitable as soon as the price difference exceeds the yield

for batteries on an individual scale, in general lead acid battery, the lifespan is quite limited in number of cycles, so it is necessary to add to the price of stored energy the price of the battery divided by the energy that the battery can store in its number of cycles ... and the result of this calculation gives a price per stored kwh of the same order as the normal price of electricity: no profitability possible even using energy that is considered free because lost if we don't store it

conversely a storage with turbine pump and reservoir, will store a much lower energy with reasonable means, but we can fill and empty the reservoir a huge number of times without using it

alas a storage system with water tank is too expensive if we have to build it only for energy storage, but if we need to store water for a fire safety reason for example ... if we have need to keep the pumps in good working condition for safety reasons too, we can design an installation also used for a certain energy storage ... and the total can become profitable

the same goes for compressed air: it is also a means of energy storage allowing a much greater number of cycles, bad because of the price of the tanks, but not bad at all at the price of the stored kwh if we take into account long service life: it is therefore too expensive a means only for energy storage, but in a workshop where there is a large compressed air tank, it is enough to modify the pressure regulation to inflate in tank in priority when electricity is the cheapest

the same for refrigerators and freezers: it would be possible to make intelligent thermostat to favor the operation when the electricity is the cheapest

When there is a need for electricity storage, the electric company will have to set up a variable rate to encourage all consumers to make this variable consumption easier than real storage.

why no such variable tariff exists? maybe because there is not enough photovoltaic and wind power yet

[sicetaitsimple]

why no such variable tariff exists? maybe because there is not enough photovoltaic and wind power yet

It happens, slowly. Engie, EDF and perhaps others have already launched "weekend" offers, we are not yet at variable rates hour by hour!

Well, you must have a Linky counter to be able to take advantage of it, of course.

[lilian07]

For the WWTP in France obviously the stock potential with the existing dams is badly exploited (10 to 15%).
With the multiplication of renewable energies, more sustained pumped storage could perhaps provide solutions to intermittency.
In general, going further, nothing is yet really optimized for renewable energies and this is normal in view of the marginal portion of the park.

[sicetaitsimple]

With the multiplication of renewable energies, more sustained pumped storage could perhaps provide solutions to intermittency.

It depends on which ENRs and at what level they are deployed. The initial deployment of PV capacities, for example the approximately 7GW that we have today in France, has a smoothing effect on market prices, because they produce during the day and therefore "plan" the price peak ( mid-day market). And therefore the WWTPs run less! It might be counterintuitive, but that's how it is!

Now, the day when there will be 50GW of PV in France, of course the STEP will pump to death all day long in the summer.