A lot (read most) is lost into space.Apart from wave power is there any other way of extracting energy from seawater? after all the sun has been beaming down on the sea for millions of years so it must contain a lot of energy.
However, water-source heat pumps can be used by homes close to an expanse of water (private lakes). Dont think they are allowed in the sea or a public lake due to freezing and ecosystem issues.
