Riverine energy technologies extract the kinetic energy from flowing water in rivers to generate electricity. Although not technically a marine resource, as part of the natural hydrological cycle, water from drainage basins, groundwater springs, and snow melt feed rivers that flow towards lakes, seas, and oceans. This movement of water downstream can be used to generate electricity via riverine turbines or hydroelectric dams.
Photo Credit: Ocean Renewable Power Company (ORPC)
Photo Credit: Martina Nolte / Creative Commons CC-by-sa-3.0 de
The main environmental concern is collision between turbine blades and marine organisms due to natural animal movements, attraction to the device, or inability to avoid turbines within strong currents. It should be noted that these turbines spin much slower than propellers on ships, and that marine mammals are typically less common in most rivers. 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 oil and grease, may enter the waterbody during spills and affect water quality. Large-scale changes in flow (from arrays) may alter the natural physical system, potentially affecting ecosystem processes, though this may be seen as a benefit for flood protection.