The salinity of the Baltic varies but is generally below 13 g/kg, which is a lot less than the salinity of the Atlantic (around 35 g/kg). This corresponds to an osmotic pressure differential around 1.8 kJ/L (1.8 MPa). If you were to build a dam which had a gravity pressure which matched this pressure differential it would be about 180 m high. So, yes, there is plenty of energy in that salinity difference, but getting it out in a cost effective manner is an open problem.
The salinity of the Baltic varies but is generally below 13 g/kg, which is a lot less than the salinity of the Atlantic (around 35 g/kg). This corresponds to an osmotic pressure differential around 1.8 kJ/L (1.8 MPa). If you were to build a dam which had a gravity pressure which matched this pressure differential it would be about 180 m high. So, yes, there is plenty of energy in that salinity difference, but getting it out in a cost effective manner is an open problem.