Accession process

Process that applicants for interruptibility service must complete in order to adopt the stablished legal framework.

AIS technology

Air Insulated Switchgear, a technology with which the ground insulation and insulation between live conductors is provided by air at atmospheric pressure.

Allocated capacity

The capacity (MW) that a participant in an explicit auction acquired by notification of the auction results and when the contestation period is closed if existing.


Commitment to energy production, energy consumption or transmission right, result of a market or auction.

Alternating Current (AC)

Electrical current in which the in flow of electrons changes direction. In Europe and most of Asia, the frequency is 50 Hz, while in North America is it 60 Hz and Japan has both 50 Hz and 60 Hz, depending on the area.

Ancillary services

Services managed by the System Operator that are required to ensure the electricity supply under the necessary conditions of quality, reliability and security. Ancillary services can be of an obligatory or optional nature. Resolution of technical constraints of the system, balancing markets (primary regulation, secondary regulation, tertiary regulation) and deviation management)

Auction cancellation

Cancellation of auctions by TSOs in case of auction IT tool unavailability or technical difficulties and/or anomalies in the information exchanges.

Auction product

Auction in which a product will be assigned. There will be as much product auctions as products to be assigned in an auction call.

Auctions specificattions

The specific characteristics of an auction, including amongst other the product made available, the day of the auction, the conditions that bids must meet in order to be accepted, the conditions for notifying the results of the auction, the deadlines for contestation and the auction session opening and closing times.

Authorized capacity

Quantity of MW authorized by the TSOs for each direction of the inteconnection and for each time period for an specific day on the set of explicit auctions, after having taken into account any capacity reductions that may affect the assigned capacities.


Balancing markets

Are those system adjustment services markets which allow the generation and demand to be balanced (deviation management services and tertiary and secondary regulation).


Area of land defined by the maximum horizontal movement of conductors and insulator strings of an overhead line due to the wind. It takes the form of a parabola between two supports.


A structure consisting of steel bars and other materials which protrudes from the main support structure to ensure the regulatory distance between the conductors and metal parts is maintained.


The power plant busbar, is that point beyond the generator but prior to the voltage transformation point in the plant switchyard, it is the starting point of the electric transmission system. The nominal net electrical output is measured at these points and the electricity for auxiliary and house loads consumed in any way related to the generation are deducted.



An element for transmitting electricity, consisting of one or more conductors and one or several layers of insulation to cover them.

Capacity auction

Process used to allocate interconnection capacity based on market mechanisms by means of explicit annual auctions, monthly auctions, daily and intraday auctions.

Capacity bids curves

Offers submitted by market partitipants to the capacity explicit auctions sorted by price (merit order).

Capacity explicit auction

Mechanism used to allocate capacity physical transmission rights.

Capacity implicit auction

Mechanism for simultaneous allocation of capacity and energy.

Capacity payments

Regulated payment to finance the medium and long-term power capacity service, offered by the generation facilities to the electricity system.

CFO Final Certificate

A document signed by the project manager and approved by the corresponding professional body to certify that the work assigned has been completed and carried out in accordance with the project.

Closed-cycle pump storage generation

Production of electricity carried out by the hydroelectric power stations whose higher elevation reservoir does not receive any type of natural contributions of water, but uses water solely from the lower elevation reservoir.

Combined cycle

Technology for the generation of electricity in which two thermodynamic cycles coexist within one system: one involves the use of steam, and the other one involves the use of gas. In a power station, the gas cycle generates electrical energy by means of a gas turbine and the steam cycle involves the use of one or more steam turbines. The heat generated by combustion in the gas turbine is passed to a conventional boiler or to a heat-recovery element to produce steam which is then used to move one or more steam turbines, increasing the yield of the process. Electricity generators are coupled to both the gas and steam turbines.

Commercial schedules

Exchange programs (MWh) in both flow directions of an interconnection resulting from transactions between market participants by means of market mechanisms.

Compensations for capacity curtailments

Payments (euros) of Electrical Systems for capacity reductions that have been necessary to apply.

Compensatory energy

Energy withdrawn from the market matching as compensation for the energy added due to grid restrictions, or vice versa.


This is the property of a material to offer more or less resistance to electrical current.


A situation in which the link which interconnects two national transmission grids is not able to accept all the resulting physical flows of the international trade which has been requested by market participants. This is done through bilateral contracts or as a result of the Market Splitting process, due to an insufficient interconnection capacity of the elements and/or the own national transmission grids in question.

Congestion incomes

Revenues derived from the management of the interconnection capacity between electricity systems.

Congestion rents from explicit auctions

Total gross income from the explicit allocation of exchange capacity.

Congetion rents from implicit mechanisms

Total gross income from management implicit mechanisms of exchange capacity management.

Continuous Current (CC)

Electrical current in which the electrons always flow in the same direction. This was the earliest type of electricity, with which generation and distribution began at the end of the 19th century.

Control gear

Group of devices consisting of switches, fuses and circuit breakers in an electricity sub-station.

Corona effect

This is an electrical phenomenon caused by the ionization of the gas around a live conductor.

Cross border balancing services

Balancing energy between two interconnected electricity systems through the coordinated action of the operators of the electricity systems, using available transmission capacity after the intraday market.

Curtailments of allocated capacity

Changes in the transmission capacity allocated in explicit auctions as a result of a reduction in the transmission capacity before the firmness deadline.


D-1 Schedule

International exchange program the day before the energy delivery date established by contracts in the Day-ahead Markets and / or bilateral contracting with physical delivery. (It represents the Daily Base Operating Program (PDBF) in MIBEL).

Daily base operating schedule (PDBF)

Is the daily energy schedule, broken-down in scheduled periods for the different energy generation selling and purchasing agents/units within the Spanish peninsular electricity system. This schedule is established by the System Operator based on the schedule resulting from matching the day-ahead market and the data regarding the execution of bilateral contracts with physical dispatch of energy.

Daily horizon

Limit of 24 hours for which the different hourly programmes are devised. A weekly horizon also exists which considers the following seven days and the rolling annual horizon, which considers the next 12 months, with a weekly breakdown.


Element used in overhead lines that is installed on conductors and ground cables to limit the vibrations caused by the effect of the wind, which can apply additional stress to insulator strings and supports.

Day-ahead market

This is the market in which the purchasing and sales transactions of electricty for the following day are carried out.


Situation where day-ahead markets are solved independently, without implicit allocation of exchange capacity.

Demand (at power station busbars)

Energy injected in to the transmission grid from the ordinary and special regime power stations and imports, after deducting the consumption of pumps and exports. In order to transport this energy to the consumption points it would be necessary to subtract the losses originated in the transmission and distribution grid.

Deviation management

Deviation management is an optional service managed and remunerated by market mechanisms. The objective is to resolve the deviations between generation and demand which could appear in the period between the end of one intraday market and the beginning of the next intraday market horizon. It is equivalent to the European product known as RR - Replacement Reserves.


A situation in which a transmission grid facility (line, transformer, busbar, etc.) is disconnected from the rest of the electricity system and, therefore, does not allow the flow of electricity through it. Additionally, the facility during unloading is earthed at one or more points with the purpose of assuring that their voltage differential remains at zero. This way, works of any type can be carried out on the element without risking the security of the people carrying them out.

Disparo (Trigger)

Non-programmed interruption of the electricity supply.

Distribution network technical restrictions

Are those technical restrictions, corresponding to requests sent by the distribution network managers to the System Operator, to guarantee the security of the distribution network under its management.


Those mercantile societies which have the function of distributing electricity, as well as to construct, maintain and operate the distribution facilities required to transfer and distribute the energy at the consumption points.


Electricity control centre

This is the centre responsible for the coordination, operation and supervision of the security of the whole of the Spanish electricity system. Amongst its functions are the scheduling of the coverage for electricity demand and programming of international exchanges, as well as zone operation and remote control. It is also the sole regulator of the Peninsular Shared Control (RCP).


Fibre optic cable

Plastic-covered material with crystalline structure in the form of a very slender wire that can transmit information as pulses of light.

Final schedule

International exchange program established at the close of the daily schedule. (It represents the Operational Programme Schedule (P48) in the Spanish Electricity System and Final Operational Programme Schedule (PHOF) in the Portuguese Electricity System).


Generation consumption

Energy used by the auxiliary elements of power stations, necessary for the everyday functioning of the production facilities.

Generation Unit

Thermal Group, pumped-storage hydroelectric plant, hydroelectric plants management unit or wind turbine generator group management unit, that provided the electric network with energy at the same point.

Generation-consumption deviations

These are the deviations originated by the modifications in the generation schedules due to the total or partial non-availability of one or several generators, variations in demand forecast of the energy buying agents, or by a new demand forecast carried out by the System Operator and which differs from the total demand matched resulting from the previous session of the Intraday Market.

Generic units

Programming units used to conduct operations in the market as a portfolio (by company) in the daily market and bilateral contrac.

GIS technology

Gas Insulated Switchgear, a technology with which the ground insulation and insulation between live conductors is provided by pressurised gas. The main advantage of using GIS technology over AIS technology is the smaller size of the installation because of the reduced distance that is required.


HAR rules

Legislation establishing the terms and conditions governing the allocation by explicit auctions of available capacity in both directions on the France-Spain in the long-term horizon and if applicable shadow auctions.

Heat capacity of a line

This is the maximum voltage that a line can carry without the temperature rising beyond what the conductors and other elements of the line can bear and without infringing safety distances. This value will depend on the nature of the line and the environmental conditions (temperature, wind and sunlight).

Hydroelectric reserves

The hydroelectric reserve of a reservoir is the quantity of electricity that could be produced in its own power station and in all the power stations situated downstream, with the total drainage of its current useable water reserves and providing that drainage occurs without natural contributions. The annual regime reservoirs are those in which complete drainage would take place in less than one year. Hyper-annual regime reservoirs are those in which the total drainage time takes more than one year.


ID shedule

International exchange program established after adjustments in the several sessions of Intraday Market MIBEL. (Represents the Final Hours Program (PHF-N) in MIBEL).

Imbalance Settlement Period

Time units for which Balance Responsible Parties' Imbalance is calculated.

Insulator string

Group of insulators and attachments that connect conductors to their supports and keep them isolated from the ground. They are made of a variable number of elements depending on the service voltage, the support required and the nature of the group of conductors, making a mobile cover around the anchor point to the support. They are classed as suspension insulators and strain insulators.

International cheduled exchanges

These are the schedules that are established between two electricity systems as a consequence of a set of scheduled individual transactions in the market by Market Participants, or by means of bilateral contracts.

International physical exchanges

The movements of energy which have taken place across lines of international interconnection during a certain period of time. It includes the loop flow of energy as a consequence of the grid design.


This is a demand management tool managed by Red Eléctrica as system operator and is used to provide an efficient and rapid response to the needs of the electricity system. The concept of interruptibility has changed into that of demand management in which large consumers who acquire energy through the electricity market can take part and can establish the corresponding service level contracts with the system operator. These companies obtain discounts on their invoices in exchange for a reduction in their electrical consumption, upon demand, and under special circumstances as determined by the system operator. In any case, the reductions of consumption to which these consumers must agree to are typified in the regulation and have as fundamental variables, the notice period, its duration and the number of times it can happen in an electrical year (November 1 - October 31).

Interruptible demand

Diference between agreggated active power consumed by the service providers and aggregated residual power.

Intraday market

The objective is to manage the adjustments occurring in the generation and demand of energy which may be produced after having fixed the day-ahead market.



A corridor within which a line may be installed. It is projected after considering the environmental fragility, social, economic and cultural aspects, and the landscape, as well as technical and legal issues.

Load factor

Measures the relationship between the energy produced during a period of time and that which would have been produced in this period working at normal power.


Marginal price

Price of the last bid allocated whose acceptance has been required in order to meet the demand required in a market call.


Spherical signalling element used to indicate junctions of electricity lines or paths, or to indicate the numbering system for ground cables.

Market agent

Entity which may access the Spanish electricity market as a participant, not just to buy energy, but also to sell it. The following may act as market agents: electricity producers, distributors and commercial agents, qualified electricity consumers, and also companies or consumers who reside in other countries and have the external agent qualification.

Market clearing

Daily generation and demand programme, with hourly breakdown, carried out by the Market Operator based on the matching process between generation and demand bids received from market agents. This programme also includes, in an individualised manner, the programmed energy excepted from the obligation to present bids in the daily market.

Market coupling

Market mechanism between several interconnected bidding zones by which simultaneously day-ahead market price is determined in each bidding zone by performing implicit auctions.

This process determines simultaneously by implicit auctions volumes and prices of energy in all interconnected areas, assigning the exchage capacity between those areas.

The coupling via certain Country Borders of day-ahead electricity markets which simultaneously effects an implicit allocation of Daily Physical Transmission Rights and a clearing of energy offers-demands.

Market operator

A mercantile society which assumes the management of the bid system for the purchase and sale of electricity in the day-ahead and intraday market under the established regulations.

Market splitting

Situation in which the energy matched in the market for one interconnection is equal to the value of ATC usually meaning different prices between bidding zones.

Measured deownward deviations

Measured downward deviations are those which result when the production measured at the power station busbars is smaller than that scheduled in the market, or when the consumption measured at the busbars is higher than that scheduled in the market. Therefore, the system must manage that difference by increasing production through the adjustment markets in real time.

Measured deviation

Difference between the energy measured at the power station busbars and the energy scheduled in the market.

Measured upward deviations

Measured upward deviations are those which result when the production measured at the power station busbars is greater than that scheduled in the market, or when the consumption measured at the busbars is lower than that scheduled in the market: Therefore, the system must manage that difference by reducing production through the adjustment markets in real time.


National demand in free market

Electricity demand of the consumers on the peninsula (measured at power station busbars) who directly contract energy from a trader or in the market.

Net generation

Production of energy measured at the generator terminals, minus the consumption in the auxiliary services and the losses in the transformers.

Net production

The electricity production of a generation unit, measured at the generator terminals, having subtracted that consumed by the auxiliary services and transformer losses

Net program and flow direction

Net balance (MWh) of all programs and flow direction.

Non-renewable energies

Those obtained from fossil fuels (liquid or solid) and their derivatives.

Non-supplied energy

This is the energy not introduced into the electricity system due to service interruptions occurred in the transmission grid.



The intention to buy or sell energy or capacity expressed by a market participant under certain conditions of execution.

Operation markets

The objective is to adapt the resulting generation programmes for the daily and intraday markets to the technical needs of quality and security required by the supply of electrical energy. These are composed of the solution of technical restrictions, the allocation of the ancillary services and deviation management. These markets are managed by Red Eléctrica in its role as system operator.

Overhead clearance

The clearance area for overhead power lines with bare conductors is defined as the strip of land defined by the projection of the outermost conductors onto the ground, considering these and their insulator strings in their most unfavourable conditions, without considering any additional distances. The most unfavourable conditions means considering the conductors and their insulator strings in their position of maximum deviation, subject to their own weight and a wind speed equivalent to 120 km/h and a temperature of 15ºC.



Entity which participates in the capacity allocation auctions, buying physical capacity rights (PCR) or later selling them directly to other entities. These entities are subject to the arranged operating (P.O. 4.1 and P.O. 4.2) and in the Rules of Capacity Allocation of the France-Spain Interconnection (IFE Rules) or Rules of Capacity Allocation of the Portugal-Spain Interconnection (IPE Rules). The participants are the counterparts of the respective TSO in the Declaration of Acceptance of Rules IFE/IPE.

Participants entitled to nominate Transmission rights at FR-ES border

List of participants entitled to exchange energy between electrical systems of France and Spain.

Percentage of hours with 100% of use

Percentage of hours where 100% of NTC was used.

Price convergence

Situation in which the energy matched in the market for an interconnection does not exceed the value of ATC and therefore the same price is recorded in both bidding zones on each side of the interconnection.

Primary control reserve

Supplementary service of a mandatory and non-remunerated nature provided by coupled generators and which aims to automatically correct instantaneous imbalances between production and consumption. It is provided by varying the power of the generators immediately and autonomously by actuating the turbine speed regulators in response to frequency variations. It is equivalent to the European product known as Frequency Containment Reserves (FCR).

Producible energy

Maximum quantity of electrical energy that theoretically could be produced considering the water supplies registered during a specific period of time and once the supplies used for irrigation or uses other than the production of electrical energy have been deducted.

Producible hydroelectric

Maximum quantity of electricity that theoretically could be produced considering the water supplies registered during a specific period of time, and once the supplies used for irrigation or uses other than the generation of electricity have been subtracted.

Producible hydroelectric index

This is the quotient between the producible energy and the average producible energy, both related to the same period and to the same hydroelectric equipment.

Producion (at generator terminals)

The electricity production of a generation unit, measured at the outgoing generator terminals.

Production (at power station busbars)

Energy measured at the generator terminals having deducted the consumption required for generation and pumped storage.


Amount (in MW) of interruptible power. There are 2 different products depending on the amount of interrumpibility power provided to the system (5 MW and 90 MW).

Programming Unit

Thermal group, pumping power station, management unit of hydroelectric power stations or management unit of a set of wind mills in a wind farm which evacuate energy in the same grid node.


Physical Transmission Right.

Pump consumption

Electrical energy used by pumped storage hydroelectric power stations for elevating water from the lower to the upper reservoir for the generation of electricity.


Qualification process

Pre-qualification process that applicants for interruptibility service must complete in order to participate in the auctions.

Qualified consumers

Is a consumer who can choose the supplier of their electrical energy in accordance with Royal Decree Law 6/2000 of 23 June. As from 1 January 2003 all consumers of electrical energy are considered as qualified consumers. With Law 17/2007 of 4 July coming in to force, which modified Law 54/1997, the figure of qualified consumer disappeared and remained integrated under the concept of consumer. In accordance with the cited law, consumers who acquire energy directly from the generation market are known as Direct Market Consumers.



Variation on the energy matched in the daily market, as a result of the execution of the successive intraday markets or ancillary services.

Real time restrictions

The process carried out by the System Operator consisting of the resolution of the technical restrictions identified during real-time operation of the system by means of the modification of the schedules of the Programming Units.

Regulation deviations

Deviations which occur between two electrical systems and are measured as the difference between the scheduled international exchanges and the physical international exchanges.

Renewable energies

Those obtained from natural resources. These different types of energy sources include hydro, hydroeolian, wind, solar photovoltaic, thermal solar, biogas, biomass, geothermal and renewable wastes.


Detected needs which are attempted to be covered during a market session.


Reserves established by the system for regulation. This is done with the objective of maintaining the generation-demand balance, correcting involuntary deviations which take place during operation in real time with the European system, or of the frequency deviations of the system with respect to the scheduled values.


Secondary capacity market

A mechanism which allows the transfer and resale, on behalf of a participant, of acquired physical capacity rights in the auctions, or by means of transfers.

Secondary regulation

An optional ancillary service whose purpose is to maintain the balance between generation and demand, correcting the unintentional deviations with respect to the schedules for the Spanish Control Block and frequency deviations. Its temporal working horizon ranges from 30 seconds to 15 minutes. It is remunerated under two concepts: capacity (reserves) and usage (energy). It is equivalent to the European product known as aFRR - automatic Frequency Restoration Reserves

Secondary reserves and secondary regulation

Secondary regulation is an optional ancillary service with the objective of maintaining the generation-demand balance, correcting deviations with respect to the schedules for the Spanish Control Block, and frequency deviations. Its temporary action horizon stretches from 20 seconds to 15 minutes. This service is remunerated by means of market mechanisms via two concepts: availability (reserves) and usage (energy). It is equivalent to the European product known as aFRR - automatic Frequency Restoration Reserves.

Security corridor

A strip of land underneath the conductors of an overhead power line, including the blowout (maximum horizontal movement of these due to the wind), plus an additional safety area established by law (Royal Decree 223/2008, Decree 315/1986 and regulation of autonomous communities).


Insular and extra-peninsular electricity systems. Refers to the electricity systems of the Balearic Islands, the Canary Islands and autonomous cities of Ceuta and Melilla.


Meeting of the Market.


The central core on which the other elements of the support assembly rest.


The measurement system intends to obtain the real data of the energy sold and bought in the electrical system for its settlement to the different companies involved (generators, traders and clients mainly) as well as for the calculation of the access tariffs billing. The Power Measurement Information System (SIMEL) comprises all these elements, that is, the measurement equipment installed at border points among activities, the secondary hubs, which receive information from the measurement equipment allocated to each of them and the main hub of electrical measurement, as well as the communications among them.


System Operator's Information System

Solar photovoltaic

Sunlight converted into electricity through the use of solar cells, generally made of semiconductor material that, when exposed to sunlight, generates electricity.

Solar thermoelectric

Heat produced by solar radiation that can be taken advantage of for the production of mechanical energy and, subsequently, electricity.


The horizontal distance between two consecutive supports of a power line.


A facility which forms a point in the electricity transmission grid, or the boundary between transmission and generation or distribution. It contains one or several levels of voltage known as facilities.

Support exchanges

Schedules which are established between two electricity systems to guarantee the conditions for the security of supply of either of the two interconnected systems. This is done in case of emergency to solve a specific risk situation in the operation of one of the systems and with the previous agreement between the respective operators and in the absence of alternative means of resolution in the system requiring support.

Surplus/deficit os deviations

Difference between the amount of the settlements of the deviations and the energy used to maintain the generation-demand balance.


Generic term for the control gear in an installation (switches, circuit breakers, transformers, etc,).

System adjustment services

Services required to ensure the electricity supply under the necessary conditions of quality, reliability and security. The adjustment services can be of an obligatory or optional character. Resolution of restrictions due to guarantee of supply, resolution of technical restrictions of the system, ancillary services and deviation management are all considered adjustment services.

System operator

A mercantile society whose main function is to guarantee the continuity and security of the electricity supply, as well as the correct coordination of the generation and transmission system. It carries out its functions in coordination with the operators and particpants of the Iberian Electricity Market under the principles of transparency, objectivity and independence. Under the current Spanish model, the system operator is also the manager of the transmission grid.


Technical restrictions due to insufficient upward reserve

Are those technical restrictions associated to the existence of insufficient energy upward reserve in the system.

Technical restrictions PDBF

A mechanism integrated in the electricity production market carried out by the System Operator consisting of the resolution of the technical restrictions identified in the Daily Base Operating Schedule by means of the modification of the schedules of the Programming Units and the subsequent process of re-balancing generation-demand.

Tertiary regulation

An optional ancillary service that, if subscribed to, is accompanied by the obligation to bid and is managed and compensated by market mechanisms. Its objective is to resolve the deviations between generation and consumption and the restitution of the secondary control reserve which has been used. This is done by means of the adaptation of the operating schedules of the programming units corresponding to generation stations and pumped storage consumption facilities. The tertiary reserve is defined as the maximum variation of power generation that a generation unit can carry out within a maximum of 15 minutes, and which can be maintained for at least 2 hours. It is equivalent to the European product known as mFRR - manual Frequency Restoration Reserves

Thermal line rating

The maximum energy which can be transmitted by an electricity line without breaking the established safety distances. This value depends on the characteristics of the line and on the environmental characteristics (temperature, wind and solar heating).

TIM (Average Interruption Time?

Time, in minutes, which results from dividing the ENS (energy not supplied to the system due to interruptions of the service occurred in the transmission grid), by the average power of the peninsular system.

Total interconnection schedules

Added value of the whole exchange programs (MWh) per flow direction of the interconnection.

Transmission grid

The electricity transmission grid consists of the primary and secondary transmission grids The primary transmission grid is made up of the lines, facilities, transformers and other electrical elements with rated voltages of 380 kV or higher, and the equipment for international connections or, where present, the connections with other electricity systems in territories outside the peninsula.

The secondary transmission grid is made up of the lines, facilities, transformers and other electrical elements with rated voltages of 220 kV or higher that are not included in the previous grid and other installations with rated voltages below 220 kV which are used for transmitting power.

Installations in territories outside the peninsula which have a rated voltage of 66 kV or higher are considered part of the secondary transmission grid, along with connections between islands whose voltage rating cannot be considered as part of the primary grid.

The transmission grid also includes all equipment for communications, protection, control, auxiliary services, land, buildings and other supporting elements, whether electrified or not, that are necessary to ensure that the specific installations of the transmission grid defined above operate correctly.

Neither the transformers of the power generators and the connecting elements of these groups to the transmission grid, nor the installation of consumers for their own use, nor direct lines are considered to form part of the transmission grid itself.

High and medium voltage electricity supply grid which is managed by Red Eléctrica.

Transmission grid technical restrictions

Are those technical restrictions identified within the global system (generation-transmission grid), that require a modification to the schedules in order to comply with the operation and security criteria for operating the system.



Use it or lose it.


Use It Or Sell It.

UIOSI compensation

Payments (euros) by the Electrical Systems to holders of non nominated long-term rights, due to MW of UIOSI that could not be made available to the day-ahead market market.

Unavailability os the productions units

A production unit is completely available if it can participate in production without any limitation in generation capacity or, when applicable, pumped storage consumption. Otherwise, it is considered unavailable, such unavailability being of a partial or total nature. The net unavailable power of a generation unit is determined by the difference between the installed net power at the power station busbars and the net power truly available.

Unfulfillement of energy balancing

Unfulfilled energy of net allocated tertiary reserves and deviation management.


Voltage control

This is an ancillary system service whose aim is to guarantee the suitable voltage control in the nodes of the transmission grid, so that the operation of the system meets the established security and reliability requirements, to ensure that the energy supplied to the final consumers is in compliance with the required quality and that the generators can work in the established conditions for its normal operation.


Accompanying measures

Voluntary actions developed by the company under its corporate responsibility charter. They are aimed at the integration of the project in the environmental, institutional and social environments by means of the project achieving sustainability with the participation of the social and environmental agents.


Bird protectors

These devices make the ground cables of overhead lines more visible, to prevent birds from flying into them.


Compensatory measures

Measures imposed by the Environmental Impact Declaration (EID) which allow the placement of an installation within the defined area of the Nature Network 2000. They are exclusively environmental and are designed to maintain and respect the Nature Network area.

Corrective measures

Set of actions carried out retrospectively to the completion of a works and that correct or minimise environmental impacts. These are usually imposed by the Environmental Impact Declaration (EID).


Electric field

In a point in space, the force exerted on a static load located at that point. Expressed in volts per metre (V/m). ( 50 Hz. Electrical and Magnetic fields REE and UNESA, 1998).

Environmental aspect

An element of the activities, products or services of an organisation having or which may an impact on the environment. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS)).

Environmental audit

A management instrument which includes a regular documented systematic and objective evaluation of the organisation, its management systems, and the procedure for protecting the environement with a view to facilitating operational control over practices that could have an impact on the environment and evaluates compliance of the environmental policies of the organisation, and in particular, its environmental objectives and goals. (European Parliament and Council Regulation no. 761/2001 dated 19 March 2001, permitting companies in the industrial sector to voluntarily join a community environmental management and auditing system (EMAS)).

Environmental behaviour indicator

Specific expression providing information on environmental behaviour in an organisation. (Standard UNE-EN ISO 14031 Environmental management. General Guidelines).

Environmental impact

Any change in the environment, either adverse or beneficial, that is caused in full or in part by the activity, products or services of any organisation. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS)).

Environmental Impact Declaration (EID-DIA, in Spanish)

Declaration by the accredited environmental authority in which the anticipated environmental effects of the project are determined. The suitability or non-suitability of carrying out the projected activity is also assessed, and in the case of being suitable, the conditions must have processes established for the adequate protection of the environment or natural resources. (Royal Decree 1131/1988, 30 September, which approves the Ruling of the execution of Royal Decree Legislation, regarding Environmental Impact Evaluation).

Environmental Impact Evaluation (EIE)

Set of technical studies and systems that assist in estimating the environmental effects that may be caused by carrying out a specific project, works or activity. (Royal Decree 1131/1988, 30 September, which approves the Ruling of the execution of Royal Decree Legislation, regarding Environmental Impact Evaluation).

Environmental Impact Study (EIS)

A detailed technical study of the potential effects on the local environment which can stem from the execution of a project, activity or political decision. Environmental impact studies should assess the existing site and conditions and evaluate the anticipated impacts on the flora, fauna, economy, historical and social factors of project or activity. Constitutes the basic document for the Enironmental Impact Evaluation process.

Environmental Management System (EMS)

That part of the general management system that includes the organisational structure, the planning of activities, responsibilities, good practices, procedures, processes and resources to develop, apply, achieve, revise and maintain the environmental policy and manage the environmental aspects. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS)).

Environmental objective

A general environmental objective, which originates from the Environmental Policy and is set out as a goal to be fulfilled by the organisation and which, insofar as is possible, is measured. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS)).

Environmental policy

The general management and intentions of an organisation with respect to its environmental behaviour, put forward officially by its management teams, including the compliance with all the legal requirements applicable to environment matters, as well as the commitment to continuously improve environmental behaviour. It establishes a framework for the company's activities, environmental targets and objectives. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS))


Hazardous waste

Those that appear on the list of dangerous residues, approved in Royal Decree 952/1997, including the containers and packages which contained them, those which have been described as dangerous by communitarian regulations and those which might be designated by the Government in accordance with that established under European regulations or in international treaties of which Spain is a part. (Law 10/1998, dated 21 April on Waste).


Magnetic field

In a point in space, the force exerted on a live element located at that point. Expressed in amps per metre (A/m). The international measuring unit is Tesla (T) or any fraction thereof, and in particular the microtesla (µT). (50 Hz. Electrical and Magnetic fields. REE and UNESA, 1998).


Nest-preventing device

A device formed by several elements made of galvanised steel, of different sizes, that prevents birds from building their nests and settling in the places where they are installed or on the device itself. (Own definition of REE).

Nesting deterrents

These are strategically placed devices consisting of several different-sized elements of galvanized steel, which deter birds from nesting in that location and encourage them to use the safer, suitably placed artificial nests.


Place of community importance (LIC)

A place that, based on the biographic region or regions where it is located, contributes greatly to maintaining or restoring a type of natural habitat (…) in a favourable state of conservation so that it can help considerably in establishing the cohesion of Natura 2000 (…) and/or contribute noticeably to maintaining biological diversity in the biogeographic region or regions in question. For the animal species occupying large areas, the places of community importance will usually correspond to specific locations inside the area in which that species is naturally distributed, presenting the physical or biological elements that are essential for them to live and reproduce. (Directive (92/43), of May 21, on the conservation of natural habits and wild fauna and flora)

Preventative measures

Actions performed, prior to carrying out a project, with the objective of avoiding possible environmental impacts.



The European Natura 2000 Ecological Network is a coherent ecological network comprised of Areas of Community Interest to be designated as Special Areas of Conservation, said Special Areas of Conservation (SACs) and Special Protection Areas (SPAs) for Birdlife, whose management shall take into account the economic, social and cultural requirements, as well as the special regional and local characteristics. (Law 42/2007 of 13 December, on Natural Heritage and Biodiversity).


Significant environmental aspect

An environmental aspect having or which may have a significant impact on the environment. (Regulation (EU) No 1221/2009 of the European Parliament and of the Council of 25 November 2009 on the voluntary participation by organisations in a Community eco-management and audit scheme (EMAS)).

Special birdlife protection zone (ZEPA)

An area of community interest for the protection of birds listed in appendix I of the Council Directive 79/409/CE of 2nd April 1979, on the conservation of birdlife.


Visual simulation

An infographic technique (based on computer applications for graphic representation) applied to obtaining the representation of a project to give an approximate idea of what it will look like in the real future situation, and showing the elements that constitute it and its integration into the execution environment. (Own definition REE).



Any substance or object belonging to any of the categories established in the appendix to the Waste Act, in which the owner disposes of or has the intention to dispose of it. In all cases, the items listed in the European Waste Catalogue (CER) will be classified as such. (Law 10/1998, 21st April, on Waste).