The French Agency for Ecological Transition


The Regulated Access to Legacy Nuclear Power mechanism (accès régulé à l’électricité nucléaire historique) grants to retailers the right to purchase part of EDF’s production at a set price. The price and volumes are set by the regulator (CRE).


The Nuclear Safety Authority (Autorité de sûreté nucléaire) is the public entity which carries out, on behalf of the French state, the missions of nuclear safety control, radiation protection (workers in the nuclear industry, environment, local communities) and the public’s information, “to protect workers, patients, the public and the environment from the risks associated with nuclear activities”.

Adjusted (for weather and/or calendar effects) consumption

The consumption that would have been observed if temperatures had been normal (as defined below “Normal temperatures”) and excluding the consumption of 29 February for leap years.

Ancillary services

Automatic frequency reserves to contain the frequency deviation of the power system in the event of a contingency and restore the frequency to 50 Hz.


Consumption, by a consumer, of all or part of the electricity generated by their own production installation. Closely related to the English-language concept of “prosumer”.


Production, by their own production installation, of all or part of a consumer’s electricity consumption. Closely related to the English-language concept of “prosumer”.

Balance responsibility party

Balance responsibility party are players in the electricity system (suppliers, consumers, electricity traders, etc.) who enter into a contractual commitment with RTE to ensure that injections and extractions within their so-called balance perimeter are matched. In the event of an overall imbalance between all the Balance responsibility parties, RTE activates the various balancing capacities (adjustment mechanism and ancillary services) to absorb the imbalance. The balancing costs are then passed on to the parties which were unbalanced within their perimeter.

Balancing mechanism

The mechanism whereby RTE procures dispatchable reserves of supply to balance supply and demand close to real time. RTE can activate production and/or load ramp-up and/or ramp-down offers from participants in the mechanism.


Alternative fuels obtained from biomass (raw material of plant, animal or waste origin). They are generally incorporated into fossil fuels.


Carbon dioxide equivalent : a comparative emissions measurement index of different greenhouse gases representing their global warming potential. The volume of gas emitted is converted into the equivalent quantity of carbon dioxide needed to reach the same global warming potential.


French domestic tax deducted from the electricity bill of electricity suppliers (Contribution au service public de l'électricité).

Capacity factor

For a given production type, the capacity factor is defined as the ratio between production and installed capacity. In RTE’s Electricity report, the monthly and yearly capacity factors correspond to the monthly or yearly average of the half-hourly capacity factors. 


Climate is a statistic on long time scales of meteorological conditions (from a few months to a few million years) for a given region. Example: oceanic climate, temperate climate, etc.

Combined-cycle gas turbine plant (CCGT)

A technology consisting of the association of a steam turbine and a gas turbine, which results in a better heat rate than conventional gas turbines.

Commercial / physical exchanges

Commercial exchanges are the result of a commercial transaction bewteen market participants which are located in different countries (or bidding zones). Physical exchanges account for the actual electricity flows on interconnectors between countries, and can differ from commercial exchanges

Commission de Régulation de l’Énergie (CRE)

The French Energy Regulatory Commission (Commission de régulation de l’énergie – CRE) is an independent administrative authority created when the energy markets were opened up to competition. The law of 10 February 2000 on the modernisation and development of the public electricity service, now codified in the Energy Code, gave it the task of regulating these markets. The CRE contributes to the smooth operation of the electricity and natural gas markets for the benefit of end consumers and in line with energy policy objectives.

Core (CWE)

Region for calculating exchange capacity and market coupling, including France, Germany, Belgium and the Netherlands, Austria, Slovenia, Poland, the Czech Republic, Slovakia, Croatia, Hungary and Romania.

Coverage rate

The consumption coverage rate is the ratio between the output of a given generation type, and demand. In the Electricity review, the monthly and annual coverage rates correspond to an average of half-hourly coverage rates.

Demand peak

Time steps when electricity demand is highest.

Dispatchable production unit

A production unit which can be started up and/or modulate its output on demand (thermal and nuclear power plants, hydroelectric plants with pumped storage, etc.).


European Network of Transmission System Operators for Electricity: a European association of electricity transmission system operators (TSO), with 35 member countries and 42 TSOs. Its aim is to promote important aspects of electricity policy, such as safety, the development of renewable energies and the electricity market.


One of the power exchange operator among those designated by regulators. Power exchange operators are tasked with the organisation of market coupling, and provide insurance for transactions on the day-ahead and intraday markets. The operators approved for France by the Commission de régulation de l’énergie (see "CRE") are EPEX SPOT and Nord Pool.


The European Pressurized Reactor, or EPR, is a nuclear reactor design of the pressurized water reactor (PWR) type. The EPR is part of the so-called 3rd generation of PWR.


Means of production, consumption or other (storage type) that can be modulated up or down for the needs of the electrical system or its operation

Forward price

Price negotiated in advance with a delivery date that may be a long way off, for a period ranging from a week to a year.

Fossil (fuel)-fired power generation

Production of electricity in thermal power stations fuelled by fossil fuels: gas, coal or fuel oil.

Grand Carénage

Investment programme to refurbish the existing nuclear fleet approved by EDF's Board of Directors on 22 January 2015. In addition to refurbishment and life extension, the aim of the programme is to increase the safety level of the reactors and incorporate the improvements designed in the wake of the Fukushima accident in 2011.

Gross consumption (non adjusted)

Countrywide electricity consumption (Corsica included, overseas territories not included), taking into account transmission losses but not the consumption of pumped-storage plants.

Heat wave

In France, a heatwave occurs when temperatures are high day and night for at least three days in a row. Alert thresholds are defined locally on the basis of thirty years of daily mortality data and various meteorological indicators (minimum temperature, maximum temperature, etc.). Meteorological vigilance takes account of the exceptional nature of night-time temperatures.

Imbalance settlement

Financial transaction whereby RTE passes on the system balancing costs to balance responsibility parties.

Imbalances (to the Balance responsibility perimeter)

Difference between injection and load within the perimeter of a balancing entity (see "Balance responsibility party").

Intraday prices

Electricity prices for same-day delivery.


Liquefied natural gas


Loi de programmation sur l'énergie et le climat : French for Energy-climate programmation law.

Lock hydropower plants

Mostly located in lakes downhill from mid-altitude mountains, those plants have a filling duration of 2 to 400 hours. They provide daily or, more rarely, weekly flexibility to the power system (daily demand peak, between business and non-business days, etc.).


Low-carbon electricity is electricity produced from non-fossil primary energy sources (nuclear, onshore and offshore wind, solar photovoltaic, etc.).

Low-carbon rate

Proportion of the total volume of electricity generated that comes from low-carbon sources (see "Low-carbon").


Manual frequency restoration reserve : power reserves that help RTE balance the system.



The French demand-respond products trading mechanism (Notification d'échange au bloc d'effacement).


Nominated electricity market operators : exchange operators designated by the regulators. They are responsible for organising coupling and ensuring that transactions on the daily and intraday markets are properly completed. By decision of the CRE, the NEMOs approved for France are EPEX SPOT and Nord Pool.

Non-dispatchable production unit

A means of production whose level at a given point in time depends mainly on external factors that are difficult to predict.

Normal temperatures

Average of past temperature timeseries that are considered representative of the current decade. They are based on Météo-France data, and are computed by RTE at the country level thanks to a panel of 32 meteorological stations across France.

Other hydropower plants

The plants included in the “other” category are tidal-energy plants and pumped-storage plants.Tidal energy plants harvest the energy from the tides in coastal areas where the tidal range (the height difference between high- and low-tide) is large. This range is used to generate electricity by exploiting the height difference between two basins separated by a dam. Pumped-storage plants, operating in pumping-generation cycles between a downhill and an uphill reservoir, thanks to reversible turbines-pumps, are efficient storage assets which contribute to the balance of the power system. When the reservoirs also have natural inflows, the turbine is categorized as “mixed pumped storage”, otherwise as “pure pumped storage”.

Other thermal power stations

Between 2001 and 2007 inclusive, the "Other" series included generation from distribution networks, generation from by-product gases and generation from "miscellaneous" fuels. Between 2008 and 2010, it included by-product gases and miscellaneous fuels, while production from distribution networks was broken down into fuel oil and gas. From 2011, all the entities in the "Other" series have been broken down into the gas, fuel oil and coal series.


The French Multiannual energy plan (Programmation pluriannuelle de l’énergie).

Pumped-storage hydroelectricity (PSH)

Hydroelectric units that draw water at off-peak times from a lower basin to fill an upstream reservoir (high altitude lake). The water is then turbined at peak times to produce electricity.


Replacement reserve

Renewable thermal and waste

Production of electricity in thermal power stations fuelled by : bioenergy (solid biomass and biogas), paper mill waste, household waste (of which 50% is conventionally considered renewable).

Reservoir hydropower plants

Located downhill from mid- and high-altitude mountains, those plants have a filling duration of over 400 hours and provide seasonal flexibility and storage to the power system.

Run-of-river hydropower plants

Located mainly on plains, have low reservoir heights and fill times of less than 2 hours. They therefore have little capacity for storage modulation and are dependent on the flow of rivers for production.


Schémas régionaux de raccordement au réseau des énergies renouvelables : regional grid connection schemes for renewable energies, i.e. planning documents for changes to the public electricity networks produced by RTE, in coordination with the distribution system operators, to anticipate and organise the best possible reception of renewable energies on the electricity networks


French ten-year network development plan (Schéma décennal de développement du réseau)


French Strategy on energy and climate (Stratégie française pour l'énergie et le climat)


French National low-carbone strategy (stratégie nationale bas-carbone) : published in November 2015, is France's roadmap for achieving the energy transition to a "low-carbon" economy, i.e. one that no longer relies on fossil fuels, so as to reduce or eliminate France's contribution to climate change (a contribution that is made in particular by the emission of greenhouse gases from fossil fuels and the degradation of carbon sinks). It should enable France to meet its commitments to reduce greenhouse gas (GHG) emissions by 2030 and 2050.

Spot price

Electricity price fixed in the market coupling D-1 (the day before for the next day) over 24 time bands.


According to Météo-France, the sunshine/sunlight duration is defined as the amount of time during which solar irradiance exceeds 120 W/m².

Supply-demand balance

Electricity storage possibilities are limited. For this reason, electricity supply and demand must be in balance at all times, which is ensured by RTE. A difference between supply and demand leads to a change in the operating frequency of the power system, which is 50 Hz at equilibrium.

Synchronous grid

Interconnected grid operating at the same frequency (e.g. the Continental Europe synchronous grid).


Trans-European replacement reserve exchange (see "RR")


French domestic tax on final energy consumption (Taxe intérieure sur la consommation finale d’électricité).

Temperature-sensitivity of consumption

Variation in electricity demand linked to temperature variations. For example, electricity consumption increases in winter when the weather is cold due to the high prevalence of electric heating in France.

Water reserves

The hydraulic stock at the French level represents the aggregate weekly filling rate of Lac-type reservoirs and hydraulic storage power stations. The head energy is that which can be produced at the (only) power station directly attached to the reservoir, depending on how full it is. The data published represent only the stock linked to the top energy sources and are expressed in MWh.

Wholesale prices

Can refer either to the spot price or to forward prices (see definitions in this glossary).