Sorcery wrote:Pumped storage with concrete. I wonder if it's economically feasible.
For storage you need to start with the science and particularly the second law of thermodynamics. The big question for grid AC is what proportion of the energy is lost as you go into storage and come out of it. (Round Trip Efficiency)
I found this page on Round Trip Efficiency
https://energymag.net/round-trip-efficiency/I was interested in the reference to ETES (partially because I didn't believe the quoted figure which as you will see later is at least 20% too high) so I found this page
https://www.siemensgamesa.com/en-int/pr ... -with-etesI don't like the way they highlight this
The project achieved 95% heat storage efficiency
because I know that the second law of thermodynamics will constrain electrical efficiency to around 50% at best. Any to be fair to them they do reference this in the graphic with a figure of 45% which is probably about right.
Water pumped storage has quite a high efficiency which is almost as high as batteries. I think the hassle of getting enough weights up and down with a table and the friction of moving them around will reduce the energy efficiency and unless it can be done a lot cheaper than batteries it won't beat batteries.
There was an interesting story in New Scientist today about potentially replacing Lithium Batteries with Sodium Ion Batteries. These would have the advantage of a more readily available element (Na). However, the batteries will weigh more so they are probably really grid backup batteries rather than moving batteries.
My expectation personally is that whether are a result of action to reduce climate change or whether because of geological constraints (peak oil) we will have a lower availability of energy in the future than today hence energy efficiency will be key to everything.
In the end the laws of physics will trump the laws of economics.