There is a new energy storage innovation from Finnish company Teraloop .
It is supposed to be a solution to large scale energy storage problems. They plan to store 16GWh (!!!) of energy using a large underground moving mass. Kinda enormous maglev train on circular track  .
“Put simply, the Teraloop system could be described as rotating masses which operate underground, guaranteeing a minimal environmental footprint, while staying conveniently out of sight.”
.. read more on Teraloop
Yeah, 16GWh equals the energy of an atomic bomb… whooaa. I hope they build it sturdy.
Basic physics suggests something may be wrong as shown in Finnish blog by a group of technology and physics experts . The base line is, there is no technology nor material to ever build such a thing even if you wanted to.
Since I am a kind person, I sincerely hope there is an explanation that makes sense. I really hope what they are planning really can work in this universe, and is not just meant to create an ego trip for the founders.
It seems they got some money/loan from Tekes (Finnish Funding Agency for Innovation). If they did, I sure hope it is not for innovation with mentioned specifications.
That would make we very pissed off, it’s Finnish tax payers money, damn it. I hope it is not true and this is a misunderstanding.
 Patent application
 https://kaikenhuippu.com/2016/04/12/teraloop-onko-idea-fysikaalisesti-realistinen/ (unfortunately in Finnish)