Editing Wave power (section)

=== Submerged pressure differential ===
Submerged pressure differential based converters<ref>{{Cite journal |last1=Kurniawan |first1=Adi |author-link2=Deborah Greaves |last2=Greaves |first2=Deborah |last3=Chaplin |first3=John |date=December 8, 2014 |title=Wave energy devices with compressible volumes |journal=Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences |volume=470 |issue=2172 |pages=20140559 |issn=1364-5021 |doi=10.1098/rspa.2014.0559 |pmc=4241014 |pmid=25484609 |bibcode=2014RSPSA.47040559K}}</ref> use flexible (typically reinforced rubber) membranes to extract wave energy. These converters use the difference in pressure at different locations below a wave to produce a pressure difference within a closed power take-off hydraulic system. This pressure difference is usually used to produce flow, which drives a turbine and electrical generator. Submerged pressure differential converters typically use flexible membranes as the working surface between the water and the power take-off. Membranes are pliant and low mass, which can strengthen coupling with the wave's energy. Their pliancy allows large changes in the geometry of the working surface, which can be used to tune the converter for specific wave conditions and to protect it from excessive loads in extreme conditions.

A submerged converter may be positioned either on the seafloor or in midwater. In both cases, the converter is protected from water impact loads which can occur at the [[free surface]]. Wave loads also diminish in [[Nonlinear system|non-linear]] proportion to the distance below the free surface. This means that by optimizing depth, protection from extreme loads and access to wave energy can be balanced.