Glossary

​This page contains a list of terms and definitions relevant to offshore wind. These terms aid in the full understanding of concepts within the modules.

Term Definition
AC transmission Often the economical solution for offshore wind facilities that are reasonably close to the final interconnection point (e.g. less than 30 to 50 miles). Cables generate reactive charging currents that use up a portion of the cable capacity needed to transmit the wind-generated power.
Anchor Piles Hollow steel pipes driven into the seabed by piling hammers.
Anemometer Measures the wind speed and transmits wind speed data to the controller.
Array Cables A network of array cables link the wind turbines together and deliver power from the turbines to the offshore substation.
Blades Blades capture the wind's energy and convert it into mechanical energy. Turbines have two or three blades. Wind blowing over the blades causes the blades to "lift" and rotate.
BOEM Bureau of Ocean Energy Management.
Cable Landing Horizontal direction drilling, a common method for landing export transmission cables from offshore wind farms, minimizes environmental impacts and disruption to beaches and the shoreline.
CAPEX All expenditure in the period of construction up to the date the wind farm is commissioned (first power).
Controller Starts up the machine at wind speeds between 8-15 mph and shuts off the machine at about 65 mph.
Converter Converts direct current into alternating current.
Converter station Converts electricity between Alternating Current (AC) and Direct Current (DC). AC is used in each country’s transmission system, while DC is used for sending electricity long distances along the subsea cables.
Crane Barges & Jackup Barges Widely used to lift pre-assembled wind turbines or support structures during installations.
Decomissioning Completely dismantling the wind farm.
Drag Anchor Composed of a fluke and a shank, which are dragged into the seabed.
Dredging Clean out the bed of (a harbor, river, or other area of water) by scooping out mud, weeds, and rubbish with a dredge.
Export Cable The export cable is buried deep enough to avoid disturbing ocean users and wildlife, and it transmits power from the offshore substation to the onshore substation.
Foundation Foundations secure the tower and above-water turbine components to the sea floor. A variety of technologies are available, including jackets, monopiles, and gravity-based foundations.
Gearbox Connects low-speed shaft to high-speed shaft and increases rotational speeds from 30-60 rotations per minute to 1200 to 1500 rpm.
Generator Transforms kinetic energy it recieves into electricity.
Gravity Anchor Hollow boxes filled with high-density material.
Gravity Base Concrete based structure which consists of sand, rock-filled and iron ore filled inside the base and a central concrete or steel shaft from the transition piece to the turbine tower. The GBS is suited for water depths greater than 20 m.
GW Gigawatt.
GWh Gigawatt hour.
Heavy Lift Cargo Vessels Feature large cargo areas which ensure the vessels to carry heavy modular components to suit specific project requirements.
High-speed shaft Drives the generator.
Horizontal-axis Turbines Has three blades and operate "upwind," with the turbine pivoting at the top of the tower so the blades face into the wind.
Hub The hub supports the blades and houses the pitch system, which optimizes blade angle and rotation speed.
Hydraulic hammer Used to drive the monopile into the seabed.
Interconnectors Huge deep undersea cables that bring electricity onshore.
Jacket Structure Four-legged piles with interconnected cross braces having a diameter of about 2 m. The base piles are nailed inside the seabed to the adequate water depth with the support of pile sleeves. These offshore structures are suitable for locations having a water depth between 25 m and 50 m.
Landfall Refers to the point at which the cables carrying power from an offshore wind farm reach the shore.
Levelized cost of energy (LCOE) The price at which the generated electricity should be sold for the system to break even at the end of its lifetime.
Module Offshore Substation Divided into several parts including transformer module, medium voltage module, backing power module, auxiliary system module, control module, etc. Each module is firstly installed on land and then transported to destination by ship. Finally all modules is installed and connected to become a offshore substation.
Monopile The installation involves hydraulic hammering of the monopiles into the seabed, which is typically 500–800 tons in weight with a diameter of 5 m–6 m, and 50 m–60 m in length. These types of structures are suitable for sites having a water depth ranging from 0 to 30 m.
Monopoles The steel structures on which wind turbines are mounted.
MW Megawatt.
Nacelle The nacelle houses the components that convert mechanical energy to electrical energy.
New Jersey Offshore Wind Supply Chain Registry "Create a free online portal where investors exploring offshore wind-related projects in New Jersey will be able to find Jersey-based companies to partner with or purchase from."
OCS Outer Continental Shelf.
Offshore Substation The offshore substation collects and stabilizes the power generated by the turbines, preparing it for transmission to shore.
Onshore Connection Electricity is transferred to the existing transmission network.
Onshore transsion grid Distributes the electricity to ratepayers.
Ornithological surveys Establish the presence and behaviour of birds within the wind farm boundary and surrounding areas.
OWF Offshore wind farm.
Power Transmission type Meaning high voltage AC or high voltage DC (HVDC).
Repowering Replacing the old turbines with the latest larger and more efficient models.
Rotor The blades and the hub together.
Semi-Submersible A number of large columns linked by connecting bracings / submerged pontoons. The columns provide the hydrostatic stability, and pontoons provide additional buoyancy. The foundation is kept in position by catenary or taut spread mooring lines and drag anchors.
Spar Buoy A cylinder with low water plane area, ballasted to keep the centre of gravity below the centre of buoyancy. The foundation is kept in position by catenary or taut spread mooring lines with drag or suction anchors.
Staging Port The base for all shore operations and logistics.
Substation Where electricity is converted to high voltage current (+150 kV).
Suction Bucket Visualised as upside-down buckets, which are lowered into the seabed to anchor the offshore structures. The water is pumped out of the bucket, thereby reducing the pressure inside the bucket skirt.
Suction Caisson Hollow cylinder with a cap, which is installed by the pressure difference created by pumping water from the caisson.
Tension Leg Platform Highly buoyant, with central column and arms connected to tensioned tendons which secure the foundation to the suction / piled anchors.
Tower The tower supports the mass of the nacelle, hub, and blades.
Transformer Raises the voltage (33 kV - 66 kV) in order to transport it across the wind farm.
Transition Piece Connecting monopile foundation with turbine tower.
Tripod Lightweight three-legged steel jacket compared to a standard lattice structure. Under the central steel column, which is below the turbines, there is a steel frame that transfers the forces from the tower to the three steel piles. Piles are installed at each leg position to anchor the tripod to the seabed. The three piles are driven into the seabed a range between 10 m and 20 m.
Tugboat The most economical and are often used for towing non-self-propelled barges or floating foundations. maneuvers other vessels by pushing or pulling them either by direct contact or by means of a tow line.
TWh Terawatt hour.
Upwid Turbine Operates facing into the wind.
Vertical-axis Turbine Omnidirectional, meaning they don’t need to be adjusted to point into the wind to operate.
Voltage Source Converter (VSC) Converts DC to AC, can operate better with the limited system strength provided by the offshore wind generators.
Wind Shadow Occurs when turbines reduce the wind’s strength as it travels downstream (onshore wind).
Wind Vane Measures wind direction and communicates w/ yaw drive to orient the turbine properly with respect to the wind.
Yaw Drive Keeps rotor facing into the wind as the wind direction changes.
Yaw Motor Powers the yaw drive.