Underwater storage of electricity with 70% efficiency

[Eric DUPONT]

concretely a concrete silo of 10 m side could store 1000 kwh

[sicetaitsimple]

At what storage pressure?

[Eric DUPONT]

20 bar. 1 kg of air = 60 wh

[ENERC]

Again, there is little need for short-term storage - 24-hour storage is enough to balance the power grid.
In addition, over 24 hours, we can do piloting (hot water tank, charging cars, hot / cold groups).

Regarding daily storage, I have no concerns because we have the technical solutions available and we are going to deploy hundreds of GWh in automobile batteries.

The real challenge is long term storage. And I don't believe in compressed air (even underwater), nor in liquid nitrogen: the storage volumes would be just insane.

I only see two solutions:
- a hydrogen + nitrogen solution (ammonia). Ammonia is very easily liquefied and easily used in a power plant (ammonium nitrate should be avoided anyway. )
- a hydrogen + carbon solution (methane, ethanol, methanol, alkanes, etc.). The advantage is that we can recover the carbon to store it with a view to sequestering CO2.

[Eric DUPONT]

By way of comparison 1 cubic meter of air at a depth of 200 m will store around 1 kWh while 1 cubic meter of liquid nitrogen at - 195 ° C would store around 160 kWh, that's nothing insane.
Hydrogen + carbon must be forgotten since it takes carbon and ammonia I think we must also forget.

So the underwater compressed air solution, for a 1 Mw wind turbine it would take a 10 m cube to store one hour of production, as we are no longer on 10 Mw wind turbines and we no longer need 200 hours of storage ...

[sicetaitsimple]

- a hydrogen + nitrogen solution (ammonia). Ammonia is very easily liquefied and easily usable in a power station

Is that so? Do you have a source?

[Christophe]

It seems to me, to verify, that ammonia is used in this technology, the ETM: energies-renewable / energy-heat-of-a-sea-of-energy-future-not realy-t4853.html

I found this too, a CNRS journal on energy storage

[Eric DUPONT]

to store hydrogen I think the simplest is low pressure tanks like 30 bar which avoids losing too much energy during compression. but the problem of hydrogen is the overall efficiency which does not exceed 50% in addition to all the problems of either ammonia safety or the cost of the platinum fuel cell.

I think that with liquid nitrogen there is a way to do better than 60% if already instead of storing liquid nitrogen we are content to store liquid air.

for underwater storage, if the concrete tank is simple, you need a surface station with air hose cables, to ultimately store a few hours of production, maybe it would be easier in a lake where there is not storms.

for the hydrogen there was solid storage with the ammonia but blah
https://www.usinenouvelle.com/article/d ... ene.N49298

[ENERC]

- a hydrogen + nitrogen solution (ammonia). Ammonia is very easily liquefied and easily usable in a power station

Is that so? Do you have a source?

The principle is to crack the ammonia into H2 / N2 and send it to the turbine.
Description of a project to convert a GTCC from CH4 to H2 here: https://www.mhi.co.jp/technology/review ... 554180.pdf

[sicetaitsimple]

Yes, we are not yet, and by far, at " and easily usable in a power station "