8.1: Introduction

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There are several ways of extracting energy from the oceans and seas. We will list them in the order of the most realistic −→the least realistic:

Wave energy (the most realistic option);
Tidal energy (already being used, but at a small scale);
Thermal methods (based on the difference of surface water tempera- ture, and deep water temperature (prototypical installations);
Energy of oceanic currents (possible, but not yet harnessed – and maybe it’s better to leave it like that?).
Osmotic (salinity gradient) power generation

A good auxiliary text to the introduction to this chapter may be this European Commission document which provides a brief but comprehensive review of what energy resources the world has in oceans. Current research on renewable ocean energy resources is focused primarily on wave energy. If one assumes that all current research projects sum up to 100%, then – according to a very rough estite by the author – 50% are projects in this area; 25% are those on the energy potential of tidal currents; 10% each are those on tidal barrages and on Ocean Thermal Energy Conversion (OTEC), and 5% are dedicated to the exploitation of water salinity gradient using methods based on the phenomenon of osmosis.

As far as wave power is concerned, it should be stressed that it receives a strong interest from OSU researchers. OSU is a member of the Pacific Ma- rine Energy Center (PMEC), the other two university partners of which are University of Washington (UW) and University of Alaska Fairbanks (UAF). The OSU’s research in this partnership is focused primarily on wave energy. UW’s research on tidal energy, and UAF’s research generally on hydrokinetic energy. OSU and UW are additionally linked in the Northwest National Marine Renewable Energy Center (NNMREC) partnership.

Hydrokinetic energy harnessing, by the way, is a general term meaning “extracting energy from flowing waters”. It comprises technologies that are already close to their maturity (wave energy harnessing) as well as technolo- gies that are just emerging (extracting energy from river and tidal currents). For reviews, please see, for example: one review, or another review.