You are referring to a hydraulic accumulator[0], such systems were built in the 19th century.  There is a modern effort to use the technology in a massively scaled up fashion by Heindl Energy[1]. Their concept uses pumped water to raise a rock weight 100 meters or more in diameter.<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Hydraulic_accumulator" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Hydraulic_accumulator</a><p>[1] <a href="http:&#x2F;&#x2F;www.heindl-energy.com&#x2F;hydraulic-rock-storage&#x2F;overview.html" rel="nofollow">http:&#x2F;&#x2F;www.heindl-energy.com&#x2F;hydraulic-rock-storage&#x2F;overview...</a>