Glossary

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 Active power

A real component of the apparent power, usually expressed in kilowatts (kW) or megawatts (MW), in contrast to reactive power.

 Adequacy

A measure of the ability of the power system to supply the aggregate electric power and energy requirements of the customers within component ratings and voltage limits, taking into account planned and unplanned outages of system components. Adequacy measures the capability of the power system to supply the load in all the steady states in which the power system may exist, considering standard conditions.

 Ancillary services

Services such as provision of reactive power, or frequency response, necessary for control or operation of the power system, and which it may be beneficial to provide from generators or other system users.

 Annualised net metering

The same as net metering, but in this case the regulator averages a user’s net electricity consumption or production over the span of one full year, rather than a shorter period.

 Biofuel

One definition of is "any fuel with an 80% minimum content by volume of materials derived from living organisms harvested within the ten years preceding its manufacture".

 Black start capability

The ability to start up independently of a power grid. This is an essential prerequisite for system security, as these plants can be called on during a blackout to re-power the grid.

 C.O.S.T

European Cooperation in Science and Technology

 Capacity

The rated continuous load-carrying ability of generation, transmission or other electrical equipment, expressed in megawatts (MW) for active power or megavolt-amperes (MVA) for apparent power.

 Capacity credit

A wind turbine can only produce when the wind blows and therefore is not directly comparable to a conventional power plant. The capacity credit is the percentage of conventional capacity that a given turbine can replace. A typical value of the capacity credit is 25 per cent

 Climate change

Change of climate attributed directly or indirectly to human activity which alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.

 Confinement time

The time the plasma is maintained at a temperature above the critical ignition temperature. To yield more energy from fusion than has been invested to heat the plasma, the plasma must be held up to this temperature for some minimum length of time, calculated from scaling laws.

 Contingency

The unexpected failure or outage of a system component, such as a generator, transmission line, circuit breaker, switch or other electrical element. A contingency may also include multiple components which are related by situations leading to simultaneous component outages.

 CORDIS

Community Research and Development Information Service

 Current distribution

The variation of plasma current density within the plasma, usually expressed as a function of the distance from the magnetic axis.

 Distributed generation

Single or small clusters of wind turbines spread across the landscape, in contrast to the concentration of wind turbines in large arrays or wind power plants.

 EESD

Energy Environment and Sustainable Development: one of the four Specific Thematic Programmes of the 5th RTD Framework Programme (1998-2002).

 Efficiency

For a wind turbine describes the amount of active electrical power generated as a percentage of the wind power incident on the rotor area.

 Electricity demand

The total electricity consumption in GWh consumed by a country annually.

 Electron cyclotron resonant heating, ECR(H)

Additional heating method using Radio Frequency waves to accelerate electrons orbiting in the magnetic field.

 Emissions

The discharges of pollutants into the atmosphere from stationary sources such as smokestacks, other vents, surface areas of commercial or industrial facilities, and mobile sources such as motor vehicles, locomotives and aircraft. With respect to climate change, emissions refer to the release of greenhouse gases into the atmosphere over a specified area and period of time.

 Energy payback

The time period it takes for a wind turbine to generate as much energy as is required to produce the turbine in the first place, install it, maintain it throughout its lifetime and, finally, scrap it. Typically, this takes 2–3 months at a site with reasonable exposure.

 EURATOM

European Atomic Energy Community Treaty. Research and training activities in the nuclear sector are implemented under the EURATOM section of the Framework Programmes. Click here for details of activities implemented under FP7.

 European Fusion Development Agreement, EFDA

The European Fusion Development Agreement that coordinates the work within the European Union and Switzerland on controlled thermonuclear fusion. EFDA has been in force since 1 January 1999.

 Fast wave current drive

Current drive produced by a fast wave, as opposed to a lower hybrid wave. The wave can penetrate the plasma more easily than a lower hybrid wave.

 Fault ride-through

(FRT) is a requirement of many network operators, such that the wind turbine remains connected during severe disturbances on the electricity system, and returns to normal operation very quickly after the disturbance ends.

 Fission

The process by which a neutron strikes a nucleus and splits it into fragments; during the process of nuclear fission, neutrons are released at high speed, and heat and radiation are released.

 Fossil fuels

Hydrocarbons, primarily coal, fuel oil or natural gas, formed from the remains of dead plants and animals. Fossil fuel is a general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth's crust over hundreds of millions of years.

 Fuel cell

An electrochemical energy conversion device. It produces electricity from external supplies of fuel (on the anode side) and oxidant (on the cathode side). These react in the presence of an electrolyte. Generally, the reactants flow in and reaction products flow out while the electrolyte remains in the cell. Fuel cells can operate virtually continuously as long as the necessary flows are maintained.
Fuel cells differ from batteries in that they consume reactants, which must be replenished, while batteries store electrical energy chemically in a closed system. Additionally, while the electrodes within a battery react and change as a battery is charged or discharged, a fuel cell's electrodes are catalytic and relatively stable.

 Fusion reaction

A fusion reaction occurs when two light nuclei (ions) approach each other so closely that their Coulomb (charge) repulsion is overcome, allowing the nuclei to fuse. The total mass of the fusion products is lower than that of the two original nuclei; the difference is converted to kinetic energy which is distributed between the products. The fusion product in a future fusion power plant, is an alpha-particle and a neutron in a deuterium-tritium plasma.

 Grid-connected

A wind turbine, for example, is grid-connected when its output is channelled directly into a national grid.