Capturing oceanic currents with turbines.
Strong ocean currents are generated from a combination of temperature, wind, salinity, bathymetry, and the rotation of the earth. The sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with no changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines.
Ocean currents are instrumental in determining the climate in many regions around the world. While little is known about the effects of removing ocean current energy, the impacts of removing current energy on the farfield environment may be a significant environmental concern. Additional concerns are similar to that of tidal energy turbines. There is concern about collision between turbine blades and marine organisms due to natural animal movements, attraction to the device, or inability to avoid the turbines within strong currents. It should be noted that these turbines spin much slower than propellers on ships. There is some concern that noise from the turbines can affect animals that use sound for communication, social interaction, orientation, predation, and evasion. As with all electricity generation, there is a slight concern that electromagnetic fields generated by power cables and moving parts may affect animals that use Earth's natural magnetic field for orientation, navigation, and hunting. Likewise, chemicals such as anti-corrosion paint and small amounts of oils and greases may enter the waterbody during spills, though some turbine designs do not require lubrication.