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The full Arcalis Energy Glossary, with additional terms, in-document links and references to sources, discussions and organisations is available upon request. Please Contact us for the list. Please also see the Copyright Notice at the foot of this page.


GLOSSARY OF WIND ENERGY TERMS

A

  • Active Power (kW or MW) - (aka. Real Power or True Power). The power that is consumed or used in an AC circuit. It is calculated by multiplying voltage and current by the power factor (the efficiency of the power being used). Active Power is always a positive number and flows from the energy source to the Load. See also Reactive Power.
  • Adequacy - The ability of the electric system to consistently maintain the overall electrical demand and energy requirements of customers, despite scheduled and reasonably expected unscheduled outages.
  • AEP - Annual Energy Production - The energy generated by a wind farm per year.
    AEP = Rated Power x Capacity Factor x 8760 Hours/Year (GWh)
  • AIP - Approval in Principle
  • ALARP - As Low As Reasonably Practicable
  • ALS - Accidental Limit State
  • Anchoring - Multiple methods are available for offshore wind turbine anchoring. For a more comprehensive analysis see anchors.
  • Anemometer - A device for measuring wind speed.
  • Array Cable - The power cables that connect offshore wind turbines to each other, or to an offshore sub-station/collector point. 
  • AUV - Autonomous Underwater Vehicle. Also see ROV
  • Auxiliary Costs - Non-turbine costs such as foundation, cables, ducting, grid connection, electricals, access roads, financial fees etc.
  • Availability - The time (in hours) that the wind turbine is capable of generating power and not being serviced or malfunctioning.

B

  • Balancing - The process of adjusting wind turbine blade weight and its weight distribution through two axes to ensure balance. An unbalanced blade creates vibration and noise which over time can destroy the wind turbine.
  • Barbados Energy Policy & Regulations

               - 2014 Jan ELPA - Electric Light and Power Act

               - 2015 Jun RER - Renewable Energy Rider

               - 2019 Jun BNEP - Barbados National Energy Policy & Implementation Plan

               - 2019 Oct ELPA(A) - Electric Light and Power Act (Amendment) 2019-2038

               - 2019 Sep FTC FIT - Feed-in Tariff 

               - 2022 Dec FTC FIT - Feed-In Tariff (1 to 10MW) 

               - 2024 Nov BLPC FIT - Feed-In Tariff - replaces Renewable Energy Rider (RER)

               - 2022 Aug RTRE - Right to Renewable Energy

               - 2025 Feb Electricity Supply Act Draft

  • Baseline/Baseload Power - the continuous supply of electricity that power plants generate to meet the minimum energy demands of a region or country. This is the consistent power level required to keep air conditioners, fridges and other electrical devices constantly running, that is, without fluctuations in the frequency or volume of power. Baseline Powerdoes not address Peak Demand.
  • BEM - Boundary Element Method - A mathematical technique where boundary conditions are used to narrow the range of possible outcomes in partial differential equations. Used in fluid dynamics, acoustics, electromagnetics and other fields. 
  • Black Start - The ability of a wind farm or wind turbine to start generating power without being commanded to by the Grid. This is required for energy security and disaster resilience as wind energy so enabled can be started after a blackout to help re-power the Grid.
  • BOP - Balance Of Plant - Excluding the wind turbines, this includes all the other functioning components of a wind farm. Includes electrics, monitoring devices and systems, cables, energy storage, grid connection components etc.
  • Braking System - If the wind turbine rotates too fast, mechanical damage or fire can occur. A braking system slows awind turbine’s rotation down to allow safe energy generation. It functions via electrical and/or mechanical means. 
  • BSI - British Standards Institution
  • BV - Bureau Veritas
  • BWM - Ballast Water Management - Using either a sequential, flow-through or dilution method to replace/top-up the water ballast in a given container. See IRCLass - Guide. 
  • BWE - Ballast Water Exchange - Same as BWM

C

  • Capacity Credit - The percentage of conventional energy generation (e.g. a Diesel or LNG Electricity Generation Plant) that a wind turbine can replace. Also see Capacity Factor.
  • CAPEX - Capital Expenditure (also see Expenditure).
  • CAR - Construction All Risks - Insurance for all construction risks. 
  • CDM - Construction Design & Management
  • CEN -  European Committee for Standardization
  • CF - Capacity Factor - Also called the Load Factor. The capacity of the wind turbine to generate energy AFTER accommodating wake loss, wind turbulence, energy loss through cables, turbine rotation for wind direction, etc. Most northern latitude wind turbines have 35%-45% Capacity Factors. In the Caribbean, we expect much higher. This is also the ratio between the average generated power and the rated (installed) power.
  • CFD - Computational Fluid Design - A modelling program designed to project wind flows, turbulence, wake effects and wind shear at a given geographical site.
  • CfD - Contracts for Difference - A (UK) scheme designed to incentivize renewable energy projects by making wind energy contracts more lucrative for developers. Sometimes closely related to carbon offset programs. Closely associated with the ARn, offshore wind auction scheme. 
  • CoE - Centre of Excellence
  • COG - Centre of Gravity
  • Cogging - The variation in speed of a PMG-WT (Permanent Magnet Generator Wind Turbine) due to magnetic flux that occurs when rotor poles pass stator poles. Cogging in PMG-WTs can hinder the start-up of smaller wind turbines at low wind speeds.
  • Control Area - An interconnected, coherent and synchronised electricity network that a single TSO manages and provides service to, connecting Loads and generation facilities. It is usually the same state, country or a geographical area that the TSO has a contract to provide services to and physically bounded by interconnection points to other Control Areasmanaged by other TSOs. 
  • Control Block - One or more Control Areas working cohesively together to ensure smooth, consistent power over a wider area than a single TSO provides services to and typically providing either harmonious synchronisation or support for this.
  • CP - Corrosion Protection
  • CPI - Consumer Price Index - A measure of inflation
  • CPR - Construction Products Regulation
  • CPS - Cable Protection System - Devices or mechanisms which protect a subsea cable from various adverse events, such as buoyancy modules, bend restrictors, bend stiffeners, and cable cleaners etc.
  • CTV - Crew Transfer Vessel - A vessel used to transport wind farm maintenance and inspection personnel to the offshore wind farm. 
  • Curtailment - A utility-controlled temporary reduction, or cut-off, of power provided to the Grid.
  • Cut-In Speed - The wind speed at which a wind turbine's blades begin to turn and produce electricity. This is around 3 - 4m/s (6 - 9 mph), currently.
  • Cut-Out Speed - The wind speed at which a wind turbine's blades are stopped automatically and/or turned out of the wind so as to avoid damage. This is around 25 - 30m/s (55 - 65 mph), currently. 
  • CZMU - Barbados Coastal Zone Management Unit

D

  • DAF - Dynamic Amplification Factor - the multiplication factor for deflections and/or stresses which should be applied to static load(s) when a dynamic load is applied to a structure
  • Darrieus Turbine - A VAWT developed by French inventor G. Darrieus in 1929. Many variants exist.
  • DD - Direct Drive - a method of drive for a wind turbine in which in which there is no gearbox. The wind turbine rotor is connected directly to an electrical generator.
  • DEA - Drag Embedment Anchor - An anchor which is buried / embedded in the seabed. Anchoring capacity is directly related to depth of embedding. See Anchoring. 
  • DECEX - Decommissioning Expenditure (also see Expenditure)
  • DEVEX - Development Expenditure (also see Expenditure)
  • DFF - Design Fatigue Factor (always = 1) - A factor applied in the design of structural components (e.g. wind turbines, cables) to address uncertainties in fatigue assessment, failures (especially criticality), and the relative difficulty of inspection, repair and (especially preventative) maintenance. 
  • DFI - Development Finance Institution
  • Diffuser - A downwind device for a HAWT to diffuse the wind stream through a rotor and so increase the wind velocity.
  • Distributed Generation - Involves individual or small numbers of wind turbines at multiple locations, unlike a wind farm of multiple wind turbines at one location.
  • DLC - Design Load Case - A key concept in design. It describes the load (i.e. forces - static, dynamic, thermal, environmental etc.) which designed component(s) must be able to address. 
  • DNV - Det Norske Veritas
  • DOF - Degrees of Freedom - The number of components in an equation that must be known before a variable is fully determined.
  • Downwind Turbine - A HAWT where the hub and blades point away from the wind direction.
  • DP - Dynamic Positioning - systems that are designed to address environmental forces such as wind, waves, currents and loads, to maintain a vessel's position and heading and allow operations to be conducted safely. 
  • DRE - Distributed Renewable Energy (also Decentralized Renewable Energy) - Typically these are energy solutions that are not centrally managed, such as off-grid, microgrid and minigrid solutions, captive power (supporting a single industry, facility or factory) and e-Mobility solutions.
  • DSU - Delay in Start-Up - Usually this is an insurance cost

E

  • e-Mobility - Use of electric vehicle batteries to power tools, homes, etc. See keba for more information.
  • Edge Device - An IoT (Internet of Things) proprietary alternative to SCADA for monitoring and control of remote systems such as wind turbines. SCADA has suffered from cyber-attacks and compromises to operating systems in recent years. 
  • EEZ - Exclusive Economic Zone - An area of ocean extending to 200 nm beyond a nation's territorial sea, over which a coastal nation has jurisdiction and control over all resources.
  • Efficiency - The amount of active electrical power generated by a wind turbine as a percentage of the wind power on the rotors' total area. 
  • EIA - Environmental Impact Assessment (aka. ES or EIS). Includes impact studies such as Visual/Audible, Residential, Industry (Tourism, Agriculture, Fish), Flora and Fauna (Coral, Transient/Resident/Visitor Marine and Wildlife), Land (Water, Geology, Drainage) and Sea (obstruction, collision hazards, navigation). 
  • EIS - Environmental Impact Study. See EIA.
  • Electricity Demand - Total electric consumption of the Grid annually (in GWh or TWh).
  • Energy Payback - The time it takes for a wind turbine to generate as much energy as produced the turbine; it includes manufacture, shipping, installation, maintenance, decommissioning, scrapping etc. Typically, payback is about 2–3 months for an average site.
  • EOG - Extreme Operating Gust - A wind event where the speed is above standard normal deviation during a long reference period, such as 50 years. Sometimes called a "Mexican Hat" distribution curve. 
  • A "Mexican Hat" Distribution curve for Extreme Operating Gusts. 
  • EPC Engineering, Procurement and Construction 
  • EPIC Engineering, Procurement, Installation and Commissioning
  • ES Environmental Study. See EIA.
  • ETA - European Technical Assessment - a voluntary procedure which allows the specification and documentation of defined performance for a component and a CE mark to be applied to a product which is only partially (or not at all) covered by a harmonised European standard. See also EOTA
  • EU - European Union
  • EWEA - European Wind Energy Association, now called Wind Europe.
  • Expenditure - There are several types of costs and investment in a typical Wind Farm project: - OPEX (Operational Expenditure) - CAPEX (Capital Expenditure) - DECEX (Decommissioning Expenditure) - DEVEX (Development Expenditure)
  • Export Cable - The power cables that connect an offshore wind farm to shore-based Grid systems.
  • External Costs - costs incurred by wind farm activities that may cause damage to multiple Receptors (e.g. human health, natural ecosystems, industry and agriculture) but not reflected in the consumer price for electricity.

F

  • FAT - Factory Acceptance Test
  • FEED - Front End Engineering Design. Also see Pre-FEED.
  • FID - Final Investment Decision (also called the Financial Investment Decision). The project developer's formal approval to proceed with a project, marking the commitment to allocate capital resources and move from the project planning stages to execution. This could also be the point at which a project or Special Purpose Vehicle is sold to a major developer with a lower risk tolerance but higher capital assets. 
  • FIDIC - International Federation of Consulting Engineers
  • FIT - Feed-in Tariff (kWh or MWh) - The rate at which a utility will purchase energy from a producer of energy.
  • FLiDAR - Floating LiDAR - A LiDAR device mounted upon a buoy, wind turbine or other fixed (floating) object.
  • FLOW - FLoating Offshore Wind
  • FLS - Fatigue Limit State - The numerical assessment of fatigue damage over the life of a structure. Typically, this involves measuring multiple load factors and difficult-to-define variables, including uncertainty factors, over periods of time and it is therefore very computationally expensive. 
  • FOW - Floating Offshore Wind. Also Fixed Offshore Wind; this term depends on context. 
  • FOWT - Floating Offshore Wind Turbine; Also Fixed Offshore Wind Turbine; this term depends on context.
  • FPSO - Floating Production Storage and Offloading Unit
  • FRT - Fault Ride-Through - A requirement of the utility, where the wind turbine remains connected during storms or disturbances and returns to normal operation rapidly after the disturbance ends.
  • FT - Fixed Turbine - An offshore wind turbine fixed to the seafloor.
  • Full Load Hours - A turbine’s AEP divided by its Rated Power. The higher the number of full load hours, the higher the turbine’s production
  • Furling - A control mechanism which limits a turbine's blade's speed by turning the rotor, or the blade, or both, out of the wind direction.

G

  • Giromill (aka. cycloturbine) - A VAWT with articulating straight blades.
  • GIS Geographical Information System - A software system which gathers, analyses stores and presents geographical or spatial data.
  • Grid - A national energy transmission and distribution system for electricity, comprised of power lines and cables, sub-stations, switching and other infrastructure, which connects energy generating facilities to consumers.
  • Grid-Tied / Grid-Connected - A wind turbine is termed "Grid-tied" or "Grid-connected" when its energy is channelled directly into a Grid.
  • Governors - Physical devices on a wind turbine that limit and control the rotation of the blades so as to prevent damage and instability.
  • Geophysical Survey – A wide area; not in-depth, non-invasive study of the sea-floor involving the following types of analysis: Seismic, Magnetic, Ground-penetrating radar, 3D imaging of seabed and subsurface to perhaps 10m. NOTE: Arcalis Energy will NOT conduct seismic explosions or other activities which could irreparably damage sea-life or the marine environment.
  • Geotechnical Survey – Compared with a Geophysical Survey, this is a smaller area, more in-depth and invasive study of the seafloor and subsurface to 50m or deeper, and detailing the condition and composition of the ground or seafloor and identifying potential hazards (e.g. floods, slides, erosion, groundswell). NOTE: Arcalis Energy will NOT conduct seismic explosions or other activities which could irreparably damage sea-life or the marine environment. 

H

  • HAWT - Horizontal Axis Wind Turbine - a wind turbine where the rotor axis is horizontal and faces into or away from the wind. Many variants exist, including 2,3, or multi-bladed turbines, multi-rotor turbines, and with multiple blade types. By far the most common wind turbine type is a three-blade monopole that faces into the wind. 
  • HPS - Hybrid Power Systems - Combinations of renewable energy generation systems in a single energy generating facility. e.g. Wind and Solar, Wind and Biomass, Wind and Hydrogen. HPS can also be used to refer to energy generation from renewable energy and conventional energy sources (diesel, gas etc.)
  • HS - Health & Safety.
    Also, HSE - Health, Safety & Environment.
    Also, QHSE - Quality, Health, Safety & Environment. 
  • HSEx - Health and Safety Executive
  • Hub - The rotating centre to which the blades are connected on a wind turbine. Also called the nacelle. 
  • Hub height - The height of the centre of the hub above ground.
  • HV - High Voltage
  • HVAC - High Voltage Alternating Current
  • HVDC - High Voltage Direct Current

I

  • IALA - International Association of Lighthouse Authorities
  • ICAP- Installed Capacity (at Peak) - Also known as Rated Capacity. The sum of the Rated Power of all wind turbines in a wind farm (MW). This is the maximum power the wind farm could produce if Capacity Factor =100% and no variables such as calm days, turbulence, wake loss, and cable losses impacted performance. 
  • IEA - International Energy Agency
  • IEC - International Electrotechnical Commission.
  • IEC Classes - A set of standards published by the IEC, and in particular the definition of classes of wind turbine relative to the max wind speed it can accommodate.
  • IPP - Independent Power Producer - a privately owned and operated energy generation company that is not part of a utility.
  • ITT - Invitation to Tender
  • ISO - International Organization for Standardization.
  • ISO - Independent System Operator. See TSO. 
  • ILA - Integrated Loads Analysis - An analysis which confirms the integrated wind turbine (nacelle, tower, foundations/anchors, floater, blades etc.) addresses the loads and stresses identified in the design requirements for the site. 
  • IMCA - International Marine Contractors Association
  • IMO - International Maritime Organization

J

  • JIP - Joint Industry Project
  • JV - Joint Venture


K

L

  • LCOE - Levelized Cost Of Electricity - The average net present cost of electricity generation for a wind turbine over its lifetime.
  • LD - Liquidation Damages - Compensation for intangible losses.
  • Learning Rate - The achieved reduction in production costs achieved through learning more efficient approaches for a wind energy project.
  • Levelized Costs - The present-day average cost per kWh produced by the wind turbine over its lifetime, including costs such as re-investments, operation and maintenance. Levelized costs are calculated using the discount rate and the turbine lifetime.
  • LFC - Load Frequency Control - A system that spreads the Load between different generators, ensures reasonably uniform frequency, and manages interchange schedules between Control Areas. 
  • LiDAR - LIght Detection And Ranging - A remote sensing method that uses light in the form of a pulsed laser to measure meteorological conditions at a variety of heights and angles to the ground or sea.
  • Line - Utility electrical components that provide Grid and service infrastructure, including substations, transmission and distribution power-cables. 
  • LNTP - Limited Notice To Proceed
  • Load (1) - Consumer electrical devices that receive power from the Grid or Microgrid. Demand is a different concept and refers to the power that the Load receives. 
  • Load (2) - The forces (stresses, strains and other factors) bearing on a structure. 
  • LOLER - Lifting Operations and Lifting Equipment Regulations
  • LR - Lloyd’s Register
  • LRFD - Load and Resistance Factor Design - same as LSD
  • LSD - Limit State Design - The Limit State is the point at which a structure maximally satisfies the design requirements for load or other actions on the structure. Integrity, fitness for use, durability of the structure can no longer be predicted beyond this point. Also, LRFD.

M

  • MAIB - The UK Marine Accident Investigation Branch
  • MET - Met Mast - Meteorological Evaluation Tower. A mast or tower which provides a platform for meteorological instruments (e.g. anemometers, wind speed transducers, air temperature and pressure transducers) to measure wind at (usually) 3 different heights.
  • Meteorology - the study of atmospheric conditions above ground and above the sea. Meteorology includes the study of: - Weather and Storms (frequency / path / intensity / size / type) - Wind (speed at different heights, direction, gusts, rose, spectrum) - Humidity - Temperature - Sunlight - Precipitation
  • Metocean - An analysis in which Meteorology and Oceanography studies are undertaken. 
  • MHWS - Mean High Water Spring Tide
  • MIC - Microbiologically Influenced Corrosion 
  • Microgrid - An energy distribution network, independent of the Grid, providing electrical connectivity between energy generation facilities and energy use facilities usually for a specific (and relatively small) area. The area may be larger or smaller than a given community. 
  • Minigrid - An energy distribution network providing electricity supply to a specific community. 
  • MLA - Mechanical Load Assessment 

  • Multi-Rotor - A wind turbine with two or more rotors (many variants exist). Two examples are shown on the left.

N

  • N-1 - A design rule that requires that if any single component of an electric system fails, the system as a whole will remain functional. Also termed (N-1)-safety, this is a common utility requirement for energy providers.
  • N+1 - A design rule that ensures there is a spare component available for every major component of a system, that can easily replace a single failed component. Note: N-1 and N+1 are not the same but can be complementary.
  • NA, NavAids - Navigational Aids (e.g. navigation lights on a wind turbine)
  • Nacelle - The component structure that sits at the hub of the wind turbine blades, where the generator, gearbox, and other key components are located. 
  • NCR - Non-Conformity Report
  • NDT - Non-Destructive Testing
  • Net Metering - A mechanism implemented by some utilities to allow energy generated by a consumer to be absorbed into the Grid and then to offset the bills of (or provide payment to) the consumer on the basis of the net import from (or net export to) the Grid. 
  • NIMBY - "Not In My Back Yard" - An acronym for a common attitude regarding local technological projects. 
  • Non-Spinning (Non-Synchronized) Reserve - Also called TMNSR (10-Minute Non-Spinning Reserve) - Not online and not synchronized, these reserve generation sources must be operational within a specified time (e.g. 10 minutes) and capable of sustaining this load for a specified time (e.g. 2-3 hours). Typically, these resources are expensive to start and run operationally and may use even larger quantities of fuel than Spinning Reserves. 
  • NTP - Notice to Proceed. Also, see LNTP. 
  • NWP - Numerical Weather Prediction - Weather forecasting by computational simulation of the atmosphere.

O

  • O&G - Oil and Gas
  • O&M - Operations and Maintenance 
  • Oceanography - Analysis of the ocean from the surface to the seabed. Oceanography includes the study of: - Surface (Water levels [fluctuation, history, expected vs maximum/minimum, seasonal changes], storm surges, tides, tsunamis, seiches, waves/swells [type, frequency, period, height, propagation direction, direction spectra]) - Water Composition (salinity, acidity, temperature/heat, pollution, minerals, oxygen content - Water Dynamics (stratification, currents and internal waves) - Flora and Fauna analysis (for EIS/ES) - Bathymetry – i.e. a seafloor map of crevasses, canyons, plains, bottom conditions, ideal locations for anchors etc. 
  • OCS - Outer Continental Shelf
  • OEM - Original Equipment Manufacturer
  • OMA - Operations and Maintenance Agreement 
  • OPEX - Operational Expenditure (also see Expenditure) - Costs associated with operating a wind farm.
  • OR - Operational Reserve - There are several types of reserve power used by Utilities to maintain a constant supply of electricity - See Spinning Reserve, Non-Spinning Reserve and Replacement Reserve. 
  • OSDR - Offshore Safety Directive Regulator
  • OSPAR - Convention for the Protection of the Marine Environment of the North-East Atlantic
  • OSS - Offshore Sub-Station
  • OWF - Offshore Wind Farm
  • OWT - Offshore Wind Turbine. Can be Fixed or Floating.

P

  • PLF - Partial Load Factor
  • PSF - Partial Safety Factor
  • P-Value Probability Value - The probability of certainty in a variable associated with a project. Commonly measured as P20, P50 or P90, this denotes a 20% level of certainty in project variables, a 50% level of certainty or a 90% level of certainty. Examples: a P90 AEP value indicates that AEP is expected to be exceeded 90% of the time. A P50 risk value indicates that investment has a 50% chance of payback over the project payback period. 
  • PCC - Point of Common Coupling - The point on the Grid at which other customers are, or could be, connected. This is commonly a Substation; it is not necessarily the same location as POC.
  • Peak Demand / Peak Load / On-Peak - energy demand management terms identifying the highest demand occurring over a specific period for Grid electricity. Typically periods are measured in units of power per hour, day, season or year. During the Peak Demand period, electricity must be provided at a consistent level that is significantly above average supply level (i.e. Baseload or Baseline) for an extended time. 
  • Pitch - The rotation of a wind turbine blade into or away from the wind.
  • POC - Point of Connection - The location where a wind farm's power connects to the Grid.
  • Power Curve - A graph that shows the net electricity output of the turbine versus the wind speed at hub height - usually at 10-minute intervals. 
  • PMG - Permanent Magnet Generator - A wind turbine that uses neodymium magnets to emit a magnetic field as the rotor turns, eliminating the need to create a magnet with electricity. Permanent Magnets eliminate the need for gearboxes, and are therefore more cost-efficient, reliable and lower maintenance.
  • PPA - Power Purchase Agreement
  • Primary Control - an automatic function that uses turbine speed governors to adjust power output from the wind turbine generator, maintaining a balance between energy generation and energy demand, and so enhancing operational reliability for all power systems in a Control Area. Also, Frequency Control or Primary Frequency Control.
  • PPR - Project Performance Report - Identifies the progress, possible losses and uncertainties associated with a wind energy project, and how these affect the AEP. Typically, energy production is summarised by turbine, by month, and for different P-values.
  • Primary Control Power - The power output of a WTG with Primary Control.
  • Progress Ratio - The inverse of the Learning Rate. For example, if a wind energy project has a Learning Rate of 10%, meaning that costs have reduced 10% as the project developers have learned to optimise construction, then the Progress Ratio is 90%.
  • PtX - Power-to-X - the conversion of renewable energy sources, such as solar or wind power, into different forms of energy or materials that can be stored, transported and used in a variety of applications.
  • PX - Power Exchange - A powerful software system capable of providing power, arranging, scheduling and completing power contracts, futures, options and managing power over a large area (typically a continent or portion of the world) that is independent of TSOs, Governments and all other market participants. For example: epexspot.

Q

R

  • R&D - Research and Development
  • RAG - Red/Amber/Green
  • Rated Capacity - see ICAP (Installed Capacity At Peak)
  • Rated Wind Speed - The lowest steady wind speed at which a wind turbine can produce its rated output power.
  • RCS - Recognised Classification Society
  • Re - Reynolds Number - The ratio of Inertial Force to Viscous Force in a flow of wind or liquid, such as the aerodynamic state of an operating aerofoil or turbine blade. This number is often used, with the angle of attack, to describe a blade's lift-to-drag ratio and when a stall will occur. The larger a Reynolds Number, the greater the turbulence over an airfoil or blade. 
  • Re-Powerment - The update of an outdated wind turbine with modern, more efficient technology or stronger technology, materials and components. Typically, re-powering occurs after 10-12 years and results in a higher energy output for the wind turbine. 
  • Reactive Power - Power provided by generators, synchronous condensers or via capacitors to magnetic components, for example electric motors and transformers, to condition and manage the supply of electricity. It directly influences AC electric system voltage and is part of the complex product of voltage and current.
  • Receptor (1) - A lightning reception point on a wind turbine's blade that is fed back to the lightning conductor located at the hub or nacelle. 
  • Receptor (2) - An EIA (Environmental Impact Analysis) factor such as a human, ecosystem, community or industry that may be impacted by a stressor. 
  • Reinvestments - The costs involved to replace major components of a wind turbine.
  • Reliability - The degree of performance of a system that provides electricity to customers within accepted standards and the amount desired. Reliability at a transmission level is measured by the frequency, duration, magnitude and probability of negative effects on the process of electricity generation, transmission, distribution and generation. 
  • Replacement (Regulating) Reserve - Also called TMOR - Thirty Minute Operating Reserve, Supplemental Reserve or Backup Reserve. These reserves must be fully operational in 30 minutes and must be capable of sustaining this power for two to four hours or more. It can be obtained from utility or non-utility sources, as well as from online and offline generation, and from interrupting loads. These reserves are mostly used to reduce costs by replacing the faster and more expensive reserves. 
  • RFF - Request For Feedback
  • RFI - Request For Information
  • RFP - Request For Proposal
  • RFQ - Request For Quotation
  • RNA - Rotor Nacelle Assembly
  • RoHS - Restriction Of Hazardous Substances in electrical and electronic equipment
  • ROV - Remotely Operated Vehicle - remotely-guided underwater mobile devices, usually deployed from a support vessel. ROVs are used for survey, maintenance and inspection functions. See also AUV.
  • ROW - Right of Way
  • RP - Recommended Practice

S

  • S-Rotor Savonius Rotor - A VAWT design producing high starting torque developed by the Finnish inventor Sigurd J. Savonius. See VAWT. 
  • S/S - Substation
  • S&I - Supply and Installation 
  • SAT - Site Acceptance Test
  • SB - Spar-Buoy (type of FLOW turbine)
  • SCADA - Supervisory Control And Data Acquisition - A world standard for monitoring functional and process components such as pipelines, industrial plants and wind turbines. It provides capability for notifications, alerts and alarms, as well as to remotely start and stop wind turbines and other electrical components, and review operating statistics.
  • Security Limits - The operating boundaries (thermal, voltage and stability limits) of the TSO (Transmission Service Operator - commonly the utility). Lack of adherence to these limits over a prolonged period of time will cause damage to other connected units or components and cause service interruptions, a cascading service interruption, or worse.
  • Service Point - The demarcation point between the Load side and the Line side of electricity supply. For a utility, this is commonly, though not always, a meter point. 
  • Shadow Flicker - The flickering shadow of a wind turbine's blades turning. This can cause issue to multiple receptors at great distance, especially at sunrise and sunset. 
  • SHM - Structural Health Monitoring
  • SLS - Serviceability Limit State
  • SMA - Service and Maintenance Agreement
  • Small-Signal Stability - The ability of an electric system to manage small events or issues without a loss of synchronism in the synchronous components of the system, and ensuring system oscillations are within the margins of acceptable stability. 
  • SOV - Service Operation Vessel - A support vessel for offshore wind farms that provides accommodation, workshops and/or equipment for personnel during survey and operations procedures. These are typically up to 90m in length (300ft) and can accommodate 50-75 people, staying on-location at the off-shore wind farm for days or weeks. A CTV is a specialised type of SOV. 
  • SOW - Scope of Work 
  • Spinning (Synchronized) Reserve - Also called TMSR (10-Minute Spinning Reserve) - Online and synchronised though perhaps not at full power, these generation sources must be operational immediately and fully responsive within a short time (e.g. ten minutes). Typically these resources are expensive to run operationally and use large quantities of fuel.
  • SPV - Special Purpose Vehicle. A sub-company, organisation or group which develops a concept or project into a purchasable entity with value. Commonly used for renewable energy projects to de-risk a large-scale project, it is frequently sold as an asset in its own right, once complete.
  • Stability - The ability of an electric system (Grid, energy generating facility etc.), to maintain a state of equilibrium whether in normal or abnormal system conditions or disturbances.
  • Stand-Alone Systems - Electric generation and distribution components independent of the public network or Grid, often used in remote locations where Grid connectivity is cost-prohibitive.
  • Static Load Flow Calculations - These identify the risk of system overload, voltage instability and (N-1)-safety problems. System overload can occur if transmitted power connecting through lines or transformers is above specified capacity loads.
  • Stressor - An EIA (Environmental Impact Analysis) factor that may cause stress or have an impact on a receptor. e.g. - Noise, Light, Shadow Flicker, Vibration, Seismic Disturbance. 
  • Synchronous Area - A geographic area with interconnected and synchronous electric systems that has no synchronous interconnections to any other interconnected systems outside the area. Within a synchronous area the system frequency is commonly steady (e.g. at 60Hz).

T

  • T&I - Transport and Installation
  • TAT - Technical Assistance and Training
  • Thrust Curve - A graph which shows the force applied by the wind at the top of the tower as a function of wind speed.
  • Tip Speed - Speed (m/s) of the wind turbine blade tip as it passes through the air. 
  • TLP - Tension Leg Platform (type of FLOW Turbine)
  • Transformer - An electrical component used to step up or down the voltage of an electric signal. Most wind farms have one or more dedicated transformers to step up or step down their voltage output to the Grid voltage.
  • Transient Stability - The ability of an electric system to stay synchronised when subjected to a disturbance of specified severity and also the ability to return to a state of equilibrium after this disturbance.
  • TRL - Technology Readiness Level
  • TSO - Transmission System Operator - (aka. ISO). A company that is responsible for operating, maintaining and developing a transmission system for a specific area and its interconnections.
  • Turbine Lifetime - The expected lifetime of the turbine (normally 20-30 years). Recent designs may provide a lifetime of 30-40 years. 
  • Turbulence Intensity - A measure of the turbulence of the wind over time as a function of wind speed. It is calculated for a time series of wind speed data as the standard deviation divided by the mean wind speed.

U

  • U-Shaped Curve - A common model which shows the attitudes of people to wind-farms change: positive before announcement, negative when announced, positive after completion. This is probably related to a familiarity factor. 
  • ULS - Ultimate Limit State. See Limit State
  • UNEP-GEF - United Nations Environment Programme, Division of Global Environment Facility Coordination
  • Unity - the degree to which people perceive wind turbines to be integrated with the landscape. 
  • Utility - The electricity supplier to consumers which owns and operates public electricity supply assets, including transmission, distribution and generation. On Barbados, this is Barbados Light and Power Company (BLPC).

V

  • Value Chain - Integrated but discrete activities of value-adding market segments that combined together are an industry. In the case of the wind energy industry, this could include for example wind turbine manufacturing, port development or expansion, project development, local content manufacture/assembly, financing, asset ownership, operations and maintenance, and energy distribution.
  • VAWT - Vertical Axis Wind Turbine - a wind turbine with a vertical rotor axis. Many variants exist.
  • VIV - Vortex Induced Vibration
  • Voltages - Multiple standards exist (and different ranges within those standards). In the US, in particular, there is little agreement on standard voltage ranges. The NEC is typically used for Load services (i.e. Consumer devices) and the NESC for Line services (i.e. Utility services) though there is considerable overlap and disagreement on application and jurisdiction. In the UK, 230V is used for single phase and 400V for three phase. The table on the left may help:
  • ·  VPT Variable Pitch Turbine - A wind turbine which can alter the attack angle of the blades can be dynamically rotated into or away from the wind, either manually or automatically.

  • VAWT - Vertical Axis Wind Turbine - examples shown here L-R: Helix  H-Rotor  Darrieus  Savonius

  • Voltages - Multiple standards exist (and different ranges within those standards). In the US, in particular, there is little agreement on standard voltage ranges. The NEC is typically used for Load services (i.e. Consumer devices) and the NESC for Line services (i.e. Utility services) though there is considerable overlap and disagreement on application and jurisdiction. In the UK, 230V is used for single phase and 400V for three phase. The table on the left may help:

W

  • WAsP - Wind Atlas Analysis and Application Program - A software system for predicting wind climate and energy production from wind farms produced by DTU Wind and Energy Systems.
  • WF - Wind Farm 
  • WFDT Wind Farm Design Tool - A software system that aids in the design / optimisation of a wind farm.
  • Wind Rose - A circular diagram illustrating the history of wind speed from different directions at a specific location.
  • Wind Shear - The drop in wind speed that occurs when wind moves over a surface (the sea, land obstructions like cliffs, buildings, trees, heat sinks etc.). Also, high-altitude winds that move in opposite directions to lower altitude thunderstorms, thereby "shearing" off the tops of thunderstorms and preventing further development into major storms or hurricanes. 
  • Wind Shear Profile - The increase in wind speed with height above ground or sea-level, typically shown as a curve on a graph of height vs wind speed. 
  • WOWO - Walk-On-Walk-Off - A support vessel with a gimballed gantry that connects to an offshore wind turbine, enabling maintenance and inspection personnel to access the wind turbine with minimal risk of incident in high seas. 
  • WSD - Working Stress Design
  • WT - Wind Turbine
  • WTG - Wind Turbine Generator - Another name for a wind turbine, or the generator inside the nacelle of the wind turbine.
  • WTIV - Wind Turbine Installation Vessel 

Y

  • Yaw - The rotation of a wind turbine about the tower on a horizontal axis.

Z

  • Zº  Surface Roughness - A variable that describes the "roughness" of the surface of the ground, and a variable in determining wind shear and turbulence.
  • ZVI - Zone of Visual Influence - the area around a wind farm from which wind turbines can be seen. This is usually a map with coloured areas representing the visibility of wind turbines.

MEASUREMENTS

  • D (metres)  Wind turbine rotor diameter
  • Kilowatts (kW)  A measure of energy equal to 1000 watts
  • Megawatts (MW)  A measure of energy equal to 1000 kilowatts. This is also the usual way to measure a wind farm's power - e.g. a 150MW wind farm can theoretically produce 150MW of energy per hour. However, this amount does NOT take into account the Capacity Factor. 
  • Gigawatts (TW)  A measure of energy equal to 1000 megawatts
  • Terawatts (TW)  A measure of energy equal to 1000 gigawatts
  • Microvolts (μVcm−1)  A unit of measurement of electrical fields.
  • Millitesla (mT)  A unit of measurement of static magnetic fields.
  • Wind Shear Exponent (α)  A variable to help measure a site's Wind Shear Profile above different types of terrain.

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