The hydrokinetic turbines sector is growing fast with several new concepts and prototypes being developed in many countries. Nonetheless, the hydrokinetic technology is currently in its development stage comparable to where wind turbines were 30 years ago. However, this development is expected to be faster due to the favorable political and social contexts, and to the many technological advances realized since then (new composite materials, advanced numerical simulation tools, etc).

The purpose of a hydrokinetic turbine is to extract a fraction of the kinetic energy contained in a water current in much the same way as one does with air using a wind turbine.  However, to extract energy from river and tidal flows rather than from the wind offers significant advantages, among which:

• a greater energy density — at equal rated power, a hydrokinetic turbine will have an area 20 times smaller than that of a wind turbine [1].

• a good predictability  — tidal flows can be predicted with accuracy years in advance, which is not the case for wind. River and man-made channel flows are also typically well predictable and dependable.

• a more discreet impact — visually and audibly, hydrokinetic turbines should be much more easily acceptable by the population. Indeed, when deployed on the seabed, they don't spoil the landscape and become essentially invisible.
  

[1] Considering a 4 knots (2m/s) water flow velocity and a wind speed of 25km/h (7m/s).