4 ms·
No mention of how efficient a storage method, but certainly a simple solution and potentially cheap. One interesting aspect that is not mentioned, as wind is a
by Zenst 10y ago
No mention of how efficient a storage method, but certainly a simple solution and potentially cheap.
One interesting aspect that is not mentioned, as wind is a shift in air pressures, then if there is a low to high shift, the efficiency will be slightly lower than a high to low shift. Presuming the air is pumped down during the former air pressure. Not sure of the effect upon storage capacity and maybe negligible or balances out. But still a factor.
- jcoffland 10y agoNo air is pumped down. The diagram shows "Strom" going down. In German Strom means energy or in this case electricity. Remember air is quite compressible but water is not.
- madez 10y agoStrom does not mean Energy. It means stream, as in a stream of water, which could be a river, or as in a stream of electrons, which would be electricity. Strom most often refers to Elektronenstrom.
- jcoffland 10y agoIn English energy is a loose synonym of current. My point was that in this case Strom means electricity which you agree with so I'm not sure why you are arguing about semantics.
- rini17 10y agoIn such depth underwater, difference created by atmospheric pressure is negligible. If they pumped air in, energy would be lost by compressing the air to necessary high pressure. So I think they just pump out the water and create vacuum.
- usrusr 10y agoPumping air is more "springy" than pumping water. But "springy" isn't exactly the worst thing when it comes to energy storage. Pressurized air storage exists, even though it comes with certain disadvantages, namely thermal losses. Ideally you would want to somehow harvest at least some of the "cold" created during decompression. At least with the "diving bell" variation of compressed air storage, you would store some of the energy not as gas pressure but as lifted water, avoiding the thermal penalty for this part of total capacity. But you are right, FhG are working with a permanently contained gas bubble that is compressed/expanded as needed. Many of the experiments done with the prototype where about the effect of different amounts of air and about the efficiency difference between a local bubble and a passive air connection to the surface. I am sure that FhG have put more thought into the pneumatic link idea than I could ever do and they seem to have come to the conclusion that a pneumatic connection just isn't feasible, or maybe that losses along the connection would be too big. From what I could gather from other sites (e.g. http://forschung-energiespeicher.info/en/news/aktuelles-einzelansicht/45/Das_System_laesst_sich_flexibel_einsetzen-1/ http://forschung-energiespeicher.info/en/news/aktuelles-einz... ) they seem to have a strong focus on practicality, e.g. having all the electric and mechanic components concentrated in a module that is slotted into the sphere from the top, which might make it a candidate for removal/replacement.
- dttyde 10y agoThe linked project website [1] does say, that the charge-discharge efficiency is at 80-85 % [1] http://forschung-energiespeicher.info/en/projektschau/gesamtliste/projekt-einzelansicht/95/Kugelpumpspeicher_unter_Wasser/ http://forschung-energiespeicher.info/en/projektschau/gesamt...
- Zenst 10y agoAha thank you, though they do say "The underlying studies and calculations concerning the storage capacity assume a charge-discharge efficiency of 80-85 %" So will be interesting how results corelate towards that calculation.