Glossary

Term	Definition
Acoustic Pollution	Adverse effects that result from noise generated by a turbine or turbine blades
Aquatic	Anything that takes place in water
Barrage	A dam used to increase the depth of water or to divert water into a channel for navigation, irrigation, or flood control
Benthic	Of or relating to the bottom of a body of water. The sea floor is a unique benthic habitat that must be protected during tidal power scheme installation
Blades	The board, flat (or slightly rounded) arms of some turbines that capture kinetic energy from a fluid and convert it to mechanical energy
Current	A continuous movement of ocean water in s specific direction. Currents have been likened to rivers within the larger ocean itself. Famous currents include the Gulf Stream (Eastern North America and Western Europe), the Antarctic Circumpolar, the California, The South Equatorial, the Monsoon, and the North Equatorial
Dredging	Excavation under water to gather up bottom sediment. Dredging is often necessary during building and maintenance of barrages.
Dynamic Tidal Power	A type of tidal power in which a long (30 km or more) dam is built perpendicular to the land and jutting out into the ocean. It interferes with tidal flows to create head and thus generate electricity
Ecosystem	A community of living organisms along with their related physical and chemical environment
Entrainment	The trapping of smaller aquatic life in filters, sluices, etc.
Estuary	Any location where fresh river water meets salty ocean water. Estuaries are critical habitat for spawning and early life cycle stages of many ocean organisms as well as birds
Flow	The movement of a fluid in a stream
Francis Turbine	A reaction turbine in which water moves through a spiral trajectory to push curved blades connected to the rim or a wheel
Gigawatt	One billion watts
Gorlov Turbine	A turbine that makes use of a helical blade or foil. It is not directional and can be mounted horizontally or vertically
Grid	A reference to the electrical supply lines that connect electricity producers to consumers
Head	The highest part of a body of water where water pressure is measured from
Horizontal Axis Turbine	A turbine in which the axis is parallel to the ground
Hydrofoil	A wing-shaped structure that is design to alter the flow of water and react to it
Hydrokinetic	The energy of moving fluid
Impulse Turbine	A turbine in which rotation is derived by jets of fluid impinging against the blades. There is no pressure difference for the fluid between inflow and outflow of an impulse turbine, but there is a velocity difference.
Kaplan Turbine	A reaction turbine with adjustable blades
Kilowatt	One thousand watts
Lagoon	A shallow pond that can connect with or communicate with a larger body of water. A tidal lagoon is constructed of a 360 degree barrage in a tidal basin or estuary
Lunar	Having to do with the moon
Lunar Tide	The part of the tide that results from the gravity of the moon
Marine	Anything having to do with the sea or seashore
Megawatt	One million watts
Neap Tide	A tide that occurs when the difference between high tide and low tide is the least. In other words, the lowest high tide in a month that occurs when the moon is ¼ or ¾ full. Neap tides occur when gravitational forces from the sun and moon are at right angles (perpendicular) to one another.
Ocean Thermal Power	Power derived by exploiting differences in water temperature between the surface of the ocean and deeper parts of the ocean
Osmotic Power	Power derived from water flowing between areas of low solute concentration and high solute concentration
Pelton Wheel	An impulse turbine in which cup-shaped buckets attached to the rim of a wheel are pushed by gets of water moving at high velocity.
Rance River	A river and estuary system in France that is the site of the first commercial-scale tidal barrage power system
Reaction Turbine	A turbine with curved blades in which rotation results from the pressure of a fluid. There is a pressure drop in the fluid between inflow and outflow
Salinity	The level of salt dissolved in a given quantity of water
Saltwater Intrusion	The movement of salty ocean water into fresh lake or groundwater
Scheme	In tidal energy, a scheme is a reference to the specific type of technology used to harness tidal energy. For instance, a tidal barrage scheme.
Sediment Damming	The trapping of sediment, by a dam or barrage, that would normally have flowed into the open ocean
Silt	Sand and clay that is captured by moving water and eventually deposited by it
Sluice	An artificial passage for water that usually has a gate to obstruct flow as desired
Solar Tide	The part of the tide that results from the gravity of the sun
Spring Tide	The tide that occurs when the difference between high and low tides is greatest. In other words, the highest high tide in a month. It occurs when the moon is new or full. Spring tides result when the gravitation forces of the sun and moon are parallel to one another.
Terawatt	One trillion watts
Tidal Kite	A buoyant hydrofoil that is tethered to the ocean floor by a capable and can thus “fly” or move about in the water as currents and waves push it
Tidal Mill	A system that converts energy from the tides into mechanical energy to do work
Tidal Phase	A reference to whether water is at its highest point during a 24 hour cycle (high tide) or at its lowest point (low tide)
Tidal Range	The vertical difference between high tide and low tide
Tidal Stream Generator	A tidal power scheme that uses the kinetic energy of water moving with tides to produce energy.
Turbidity	The measure of the clarity of water as a result of debris and silt
Turbine	A rotational machine that spins under force of a fluid (water, wind, steam, ammonia, etc.)
Turbine Death	The death of wildlife as a result of direct contact with the blades of a turbine
Venturi Tube	A simple, hollow structure that is widest at both ends and narrowed in the middle. It accelerates a fluid flowing through it
Vertical Axis Turine	A turbine in which the axis is perpendicular to the ground
Watt	A unit of power, defined as one joule per second that measures the rate of energy conversion or transfer.
Wave Energy	Kinetic energy that results from the oscillation of water