Water is very incompressible, so you don't really get anything in addition to the potential energy. If you decompress water from 300 bar (equivalent to 1 kilome

Water is very incompressible, so you don't really get anything in addition to the potential energy. If you decompress water from 300 bar (equivalent to 1 kilometer height of rock above it) to 1 bar (atmospheric pressure) it only expands by 1.5%.