Agency for the Cooperation of Energy Regulators (ACER) – ACER was officially launched in March 2011 and is seated in Ljubljana, Slovenia. As an independent European structure which fosters cooperation among European  energy regulators, ACER ensures that market integration and harmonisation of regulatory frameworks are done in respect of EU’s energy policy objective.

Source: ACER

Alternating Current (AC) – An alternating current is an electric current that reverses its direction at regular intervals.

Source: International Energy Agency

Ancillary services – An ‘ancillary service’ is a service necessary for the operation of a transmission or distribution system.

Source: EC


Black start – Black start is the procedure of re-establishing the electricity supply within a control area after a total disruption of the supply.

Source: ENTSO-E


Carbon Dioxide – Carbon dioxide (CO2) is a colourless, odourless and non-poisonous gas formed by combustion of carbon and in the respiration of living organisms and is considered a greenhouse gas. Emissions means the release of greenhouse gases and/or their precursors into the atmosphere over a specified area and period of time. Carbon dioxide emissions or CO2 emissions are emissions stemming from the burning of fossil fuels and the manufacture of cement; they include carbon dioxide produced during consumption of solid, liquid, and gas fuels as well as gas flaring.

Source: European Commission – Eurostat, Carbon Dioxide Emissions

Chemical Energy Storage – Chemical energy storage systems store energy in the chemical bonds between atoms. For example, excess electricity can be used for an electrolysis process, producing hydrogen and oxygen (Power to Gas). The hydrogen can then further be processed to Synthetic Natural Gas (SNG) (Methanation).

Source: EGS Brochure

Climate and Energy Package (“20-20-20” targets) – The Climate and Energy Package is a set of binding legislation which aims to ensure the European Union meets its ambitious climate and energy targets for 2020. These targets, known as the “20-20-20” targets, set three key objectives for 2020: a 20% reduction in EU greenhouse gas emissions from 1990 levels; raising the share of EU energy consumption produced from renewable resources to 20%; a 20% improvement in the EU’s energy efficiency.

Source: European Commission, Climate and Energy Package

CO2– see Carbon Dioxide.

Combined Heat and Power (CHP) – A combined heat and power unit is an installation in which energy released from fuel combustion is partly used for generating electrical energy and partly for supplying heat for various purposes.The definition of Combined Heat and Power (CHP) or “cogeneration” implies that heat and electricity are produced simultaneously in one process.

Source: EU energy in figures – Statistical Pocketbook 2013

Connecting Europe Facility (CEF)– The Connecting Europe Facility is specifically designed to promote growth, jobs and competitiveness through targeted infrastructure investment at European level. It will support the roll-out of high-performing, sustainable and joined-up trans-European networks in the fields of transport, energy, and broadband and digital services.

Source: European Commission, Connecting Europe Facility

Conventional Thermal Power GenerationConventional Thermal Power Generation is a technology for the production of electricity by fuel combustion. It may or may not include biomass use, which is also considered a renewable source of electricity. Thermal power stations cover conventional public utility power stations for the production of electricity and heat, as well as in auto producer power stations for the generation of electricity and heat sold to third parties only.

Source: EU energy in figures – Statistical Pocketbook 2013

Cost-Benefit Analysis (CBA) – A Cost-Benefit Analysis is a conceptual framework applied to any systemic, quantitative appraisal of a public or private project to determine whether, or to what extent, that project is worthwhile from a social perperctive. CBAs differ from a straightforward financial appraisal in that it considers all gains (benefits) and losses (costs) to social agents. CBA usually implies the use of accounting prices. The CBA methodology is heavily dependent on the type of project.

Source: European Commission, JRC


Direct Current (DC) -Direct current or DC electricity is the continuous movement of electrons from an area of negative (-) charges to an area of positive (+) charges through a conducting material.

Source: UCTE data handbook

DG CLIMA – The European Commission’s Directorate-General for Climate Action was established in February 2010, since previously climate change was included in the remit of DG Environment of the European Commission. DG CLIMA leads international negotiations on climate, develops and implements international and domestic climate action policies and strategies, helps the EU to deal with the consequences of climate change and to meet its targets for 2020, as well as develops and implements the EU Emissions Trading System.

Source: European Commission, DG CLIMA

DG Energy – The European Commission’s Directorate-General for Energy manages work in the area of energy policy. The issues and challenges connected to this policy require action at European level; no single national government can address them successfully alone. By working in concert, European Union Member States and European industry can develop energy sectors which best meet the needs of citizens and economy, whilst minimising damage to environment.

Source: European Commission, DG Energy

DG RTD – The Directorate-General for Research and Innovation’s mission is to develop and implement the European research and innovation policy with a view to achieving the goals of Europe 2020 and the Innovation Union. To do so, the Directorate-General for Research and Innovation supports research and innovation through European Framework Programmes, coordinates and supports national and regional research and innovation programmes, contributes to the creation of the European Research Area by developing the conditions for researchers and knowledge to circulate freely, and supports European organisations and researchers in their cooperation at international level.

Source: European Commission, DG RTD

Distribution – It means the transport of electricity on highvoltage, medium-voltage and low-voltage distribution systems with a view to its delivery to customers, but does not include supply.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/72/EC

Distribution System Operator (DSO) – A natural or legal person responsible for operating, ensuring the maintenance of and, if necessary, developing the distribution system in a given area and, where applicable, its interconnections with other systems and for ensuring the long-term ability of the system to meet reasonable demands for the distribution of electricity.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/72/EC


e-Highway 2050 Project – The e-Highway2050 project is supported by the EU Seventh Framework Programme and is aimed at developing a methodology to support the planning of the Pan-European Transmission Network, focusing on 2020 to 2050, to ensure the reliable delivery of renewable electricity and pan-European market integration. The project will result in a modular development plan for possible electricity high- ways and options for a complete pan-European grid architecture, based on various future power system scenarios.

Source: e-Highway2050 project

Electrical Energy Storage – Electrical energy storage systems store electricity without converting it to another type of energy. The most common electrical energy storage concepts are capacitors and Superconducting Magnetic Energy Storage (SMES).
Capacitors are electrical devices that consist of two oppositely charged metal plates separated by an insulator. The capacitor stores energy by increasing the electric charge accumulation on the metal plates and discharges energy when the electric charges are released by the metal plates. Capacitors could be used to improve power quality because they can rapidly provide short bursts of energy (in under a second) and store energy for a few minutes.
Superconducting magnetic energy storage (SMES) consists of a coil with many windings of superconducting wire that stores and releases energy with increases or decreases in the current flowing through the wire. Although the SMES device itself is highly efficient and has no moving parts, it must be refrigerated to maintain the superconducting properties of the wire materials, and thus incurs energy and maintenance costs. SMES can be used to improve power quality because they provide short bursts of energy (in less than a second).

Source: Center for Climate and Energy Solutions

Electrochemical Energy Storage – Electrochemical storage devices can be divided according to their design and construction into storage devices with internal or external storage. In those with internal storage, the classic batteries, also called accumulators, the electrochemical conversion process and the storing of energy cannot be separated, and therefore the amount of storable energy is directly linked with charge or discharge power. Consequently, if more energy is needed, more batteries must be used. In contrast, those with external storage, also called flow batteries, use a liquid as the electrolyte, with the electro-active material only being introduced into the device during operation. In these devices, energy capacity can be increased simply by increasing the size of the external storage tanks. Two examples of flow batteries are Vanadium Red-Ox and Zinc-bromine (Zn-Br). Several mature or nearly mature battery technologies are commercially available in form of large-scale turnkey battery storage plants, including lead-acid (Pb) and nickel cadmium (NiCd), advanced lead-acid, lithium-based, vanadium redox-flow and sodium-sulfur (high-temperature battery). Other promising battery technologies are being developed, such as metal-air and sodium-ion.

Source: E.ON Fact Sheet Battery Storage Systems and EASE

Energy Materials Industrial Research Initiative (EMIRI) -The Energy Materials Industrial Research Initiative is a European industry driven initiative, bringing together the skills and expertise of both the research community and industry to implement in a more effective way cross cutting collaborative energy materials innovation programmes for a competitive low-carbon energy sector.

Source: EMIRI

Energy Efficiency Directive (EED) – This EU Directive establishes a common framework of measures for the promotion of energy efficiency within the Union in order to ensure the achievement of the Union’s 2020 20 % headline target on energy efficiency and to pave the way for further energy efficiency improvements beyond that date. It lays down rules designed to remove barriers in the energy market and overcome market failures that impede efficiency in the supply and use of energy, and provides for the establishment of indicative national energy efficiency targets for 2020.

Source: European Commission, EED Directive

Energy Roadmap 2050 – On 15 December 2011, the European Commission adopted the Communication “Energy Roadmap 2050”. The EU is committed to reducing greenhouse gas emissions by 80-95% below 1990 levels by 2050 in the context of necessary reductions by developed countries as a group. In the Energy Roadmap 2050 the Commission explores the challenges posed by delivering the EU’s decarbonisation objective while at the same time ensuring security of energy supply and competitiveness. The Energy Roadmap 2050 is the basis for developing a long-term European framework together with all stakeholders.

Source: European Commission, Energy Roadmap 2050

ENTSO-E – The European Network of Transmission System Operators for Electricity (ENTSO-E) is the body of transmission system operators of electricity at European level and its mission is to promote important aspects of energy policy in the face of significant challenges. ENTSO-E’s goal is to become and remain the focal point for all European, technical, market and policy issues related to TSOs, interfacing with the power system users, EU institutions, regulators and national governments.

Source: ENTSO-E

ENVI committee -The Environment, Public Health and Food Safety Committee (ENVI) s currently the largest legislative committee in the European Parliament and is working to see the concerns of citizens all over Europe reflected in environmental, health and food safety legislation.

Source: European Parliament, ENVI Committee

EU Emissions Trading System (EU ETS) – The EU Emissions Trading System (EU ETS) is a cornerstone of the European Union’s policy to combat climate change and its key tool for reducing industrial greenhouse gas emissions cost-effectively. The first – and still by far the biggest – international system for trading greenhouse gas emission allowances, the EU ETS covers more than 11,000 power stations and industrial plants in 31 countries (28 EU countries plus Liechtenstein, Norway and Iceland), as well as airlines.

Source: European Commission, EU ETS

EUROBAT – The Association of European Automotive and Industrial Battery Manufacturers is the unified voice of the European automotive and industrial battery industry in policy discussions involving the industry and the European Institutions and national governments.


European Commission (EC) -The European Commission is the EU’s executive body and represents the interests of Europe as a whole (as opposed to the interests of individual countries).
The term ‘Commission’ refers to both the college of commissioners and the institution itself – which has its headquarters in Brussels, Belgium with offices in Luxembourg. The Commission also has offices known as ‘representations’ in all EU member countries.

Source: European Commission

European Energy Network (EnR) – EnR is a voluntary network currently numbering 24 European energy agencies, with responsibility for the planning, management or review of national research, development, demonstration or dissemination programmes in the fields of energy efficiency and renewable energy and climate change abatement. EnR seeks to strengthen cooperation between member agencies and other European actors on all issues relevant to sustainable energy.

Source: EnR

European Energy Research Alliance (EERA) -The European Energy Research Alliance (EERA) is an alliance of leading organisations in the field of energy research that aims to strenghten, expand and optimise EU energy research capabilities through the sharing of national facilities in Europe and the joint realization of pan-European research programmes (EERA Joint Programmes). The primary focus of EERA is to accelerate the development of energy technologies to the point where they can be embedded in industry-driven research. In order to achieve this goal, EERA streamlines and coordinates national and European energy Research [&] Development programmes.

Source: EERA

European Energy Storage Technology Development Roadmap 2030 – EASE and EERA have joined their knowledge to produce a comprehensive Roadmap describing the future European needs for energy storage in the period towards 2020-2030. The Roadmap also gives recommendations on the developments required to meet those needs.

Source: EASE Website

European Industrial Initiatives (EIIs) -EIIs are joint large scale technology development projects between academia, research and industry. The goal of the EIIs is to focus and align the efforts of the Community, Member States and industry in order to achieve common goals and to create a critical mass of activities and actors, thereby strengthening industrial energy research and innovation on technologies for which working at the Community level will add most value. In 2008, the Commission proposed to launch six EIIs: Wind, Solar (both concentrated solar and photovoltaic), Carbon Capture and Storage, Electricity grids, Bio-energy and Nuclear fission.

Source: European Commission, EIIs

European Parliament (EP) -The European Parliament is the only directly-elected body of the European Union. The 754 Members of the European Parliament, once elected, organise along political lines. They form political groups to better defend their positions and currently there are seven groups. They are elected once every five years by voters right across the 27 Member States of the European Union on behalf of its 500 million citizens. Most of Parliament’s in-depth work is done in specialised committees that prepare reports that will later be voted on in the plenary.

Source: European Parliament

European Technology Platform (ETPs) -European Technology Platforms (ETPs) are industry-led stakeholder for a that develop short to long-term research and innovation agendas and roadmaps for action at EU and national level to be supported by both private and public funding.

Source: European Commission, ETPs

European Technology Platform for Electricity Networks of the Future– The European Technology Platform for Electricity Networks of the Future, also called SmartGrids ETP, is the key European forum for the crystallisation of policy and technology research and development pathways for the smart grids sector, as well as the linking glue between EU-level related initiatives.

Source: European Technology Platform Smart Grids

European Union (EU) – The EU was created in the aftermath of the Second World War. The first steps were to foster economic cooperation: the idea being that countries who trade with one another become economically interdependent and so more likely to avoid conflict. The result was the European Economic Community (EEC), created in 1958, and initially increasing economic cooperation between six countries: Belgium, Germany, France, Italy, Luxembourg and the Netherlands. Since then, a huge single market has been created and continues to develop towards its full potential.Today the EU is a unique economic and political partnership between 28 European countries that together cover much of the continent.

Source: European Union


Feed-in Tariffs (FIT) – Feed-in tariffs are characterised by a specific price, normally set for a period of around several years, that must be paid by electricity companies, usually distributors, to domestic producers of green electricity. The additional costs of these schemes are paid by suppliers in proportion to their sales volume and are passed through to the power consumers by way of a premium on the kWh end-user price.

Source: European Commission COM (2005) 627 final

FP7 – The Seventh Framework Programme for Research and Technological Development is the EU’s main instrument for funding research in Europe and it will run from 2007 to 2013. FP7 is also designed to respond to Europe’s employment needs and competitiveness and to support research in selected priority areas – the aim being to make, or keep, the EU as a world leader in those sectors.

Source: European Commission

Frequency – Frequency of the electrical Power System that can be measured in all Network areas of the Synchronous System under the assumption of a coherent value for the System in the Time frame of seconds (with minor differences between different measurement locations only); its nominal value is 50 Hz.

Source: ENTSO-E


Green Paper – Green Papers are documents published by the European Commission to stimulate discussion on given topics at European level. They invite the relevant parties (bodies or individuals) to participate in a consultation process and debate on the basis of the proposals they put forward. Green Papers may give rise to legislative developments that are then outlined in White Papers.

Source: European Commission

Green Paper “A 2030 framework for climate and energy policies” – On 27 March 2013, the European Commission adopted a Green Paper on “A 2030 framework for climate and energy policies”. This document launches a public consultation lasting until 2 July, allowing Member States, other EU institutions and stakeholders to express their views; for example on the type, nature and level of potential climate and energy targets for 2030, but also on other important aspects of EU energy policy in a 2030 perspective. Those views will feed into the Commission’s on-going preparations for more concrete proposals for the 2030 framework which will be tabled by the end of 2013.

Source: European Commission


High Voltage Line – A High Voltage Line is a line carrying 63 kV, 90 kV or 150 kV electrical circuits. When the line is carrying 225 kV or 400 kV electrical circuits it is called an Extra High Voltage Line.

Source: ENTSO-E

Horizon 2020 – Horizon 2020 is the financial instrument implementing the Innovation Union, a Europe 20203 flagship initiative aimed at securing Europe’s global competitiveness. Running from 2014 to 2020 with an €80 billion budget, the EU’s new programme for research and innovation is part of the drive to create new growth and jobs in Europe.

Source: European Commission, Horizon 2020


IMCO committee – The Committee on Internal Market and Consumer Protection (IMCO) is a European Parliament Committee which contributes to define policies and legislative proposals on these subjects.

Source: European Parliament, IMCO Committee

International Energy Agency (IEA) – The International Energy Agency (IEA) is an autonomous organisation which works to ensure reliable, affordable and clean energy for its 28 member countries, even though it works also with non-members states. Initially it was founded in response to the 1973-’74 oil crisis and its initial role was to help countries co-ordinate a collective response to major disruptions in oil supply through the release of emergency oil stocks to the markets.

Source: IEA

ITRE committeeThe Committee on Industry, Research and Energy (ITRE) is a European Parliament Committee which contributes to define policies and legislative proposals on Industry, Research and Energy.

Source: European Parliament, ITRE Committee


Joint Research Centre (JRC) – The Joint Research Centre is the Commission’s in-house science service, with the mission to provide EU policies with independent, evidence-based scientific and technical support throughout the whole policy cycle. Working in close cooperation with policy Directorates-General, the JRC addresses key societal challenges while stimulating innovation through developing new methods, tools and standards, and sharing its know-how with the Member States, the scientific community and international partners.

Source: European Commission, JRC


Load Following – When generation closely follows the load (i.e. demand) pattern. In other words input and off-take of electricity in a given system correspond at any point in time. This is commonly referred to as the “generation follows demand” paradigm.

Source: Eurelectric report “Flexible generation:Backing up renewables”, 2011


Mechanical energy storage – Mechanical energy storage systems convert excess electricity to potential energy. This potential energy can later be converted back to electricity by using a generator. Depending on the technology, this type of storage can be used to improve power quality by balancing short-term fluctuations (Flywheels) or matching generation and demand (Pumped Hydro Storage, Pumped Heat Electrical Storage and Compressed Air Energy Storage).


Network Codes – Network Codes are sets of rules which apply to one or more parts of the energy sector. A Network Code is therfore a document setting out the code of practice, typically setting standards or operating procedures, agreed by ENTSO-E. The agreed document will subsequently be submitted to the CEER and ultimately will become European legislation.

Source: ENTSO-E, Network Codes


Photovoltaic (PV) – PV systems use photovoltaic cells to convert solar radiation into electricity. The cell consists of layers of a semi-conducting material. When light shines on the cell it creates an electric field across the layers, causing electricity to flow.The greater the intensity of the light, the greater the flow of electricity. However, a PV system can also generate electricity on cloudy days; it does not need bright sunlight to operate.

Source: SolarPower Europe


Renewable Energy Sources (RES) – ‘RES’ means renewable non-fossil energy sources (wind, solar, geothermal, wave, tidal, hydro[-] power, biomass, landfill gas, sewage treatment plant gas and biogases).

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/72/EC

Research and Development (R[&]D) – R[&]D are investigative activities that a business chooses to conduct with the intention of making a discovery that can either lead to the development of new products or procedures, or to improvement of existing products or procedures. Research and development is one of the means by which business can experience future growth by developing new products or processes to improve and expand their operations.

Source: Investopedia


Smart Cities and Communities – The Smart Cities and Communities European Innovation Partnership was launched by the EC and proposes to pool resources to support the demonstration of energy, transport and information and communication technologies (ICT) in urban areas. The energy, transport and ICT industries are invited to work together with cities to combine their technologies to address cities’ needs. This will enable innovative, integrated and efficient technologies to roll out and enter the market more easily, while placing cities at the centre of innovation.

Source: European Commission

Smart Grids – A Smart Grid is an electricity network that can cost efficiently integrate the behaviour and actions of all users connected to it – generators, consumers and those that do both – in order to ensure economically efficient, sustainable power system with low losses and high levels of quality and security of supply and safety.

Source: European Commission-European Smart Grid Task Force

Strategic Energy Technology Plan (SET Plan) – The Strategic Energy Technology Plan establishes an energy technology policy for Europe. It is a strategic plan to accelerate the development and deployment of cost-effective low carbon technologies. The plan comprises measures relating to planning, implementation, resources and international cooperation in the field of energy technology.

Source: European Commission


Ten-Year Network Development Plan (TYNDP) – The European Commission Regulation 714/2009 requested ENTSO-E to “adopt a non-binding community-wide ten-year network development plan” (TYNDP) with the objective to ensure greater transparency regarding the entire electricity transmission network in the Community and to support the decision making process at the regional and European levels. The first official TYNDP package was released on 5 July 2012, two years after the pilot TYNDP publication in 2010. The second official TYNDP it is expected to be released for stakeholders’ consultation in March 2014 with the final version being published end June/beginning July 2014.

Source: ENTSO-E

Thermal Energy Storage (TES) – TES systems use various substances to store heat or cold. There are two very different types: TES applicable to solar thermal power plants and end-use TES. TES for solar thermal power plants consists of a synthetic oil or molten salt that stores solar energy in the form of heat collected by solar thermal power plants to enable smooth power output during daytime cloudy periods and to extend power production for 1-10 hours past sunset. End-use TES stores electricity from off-peak periods through the use of hot or cold storage in underground aquifers, water or ice tanks, or other storage materials and uses this stored energy to reduce the electricity consumption of building heating or air conditioning systems during times of peak demand. The main technology categories for TES are Heat (hot water/Phase-change Material), Packed-bed Heat Storage, Molten Salt (Heat/Concentrated Solar Power thermal) and Smart Electrical Thermal Storage.

Source: EASE

THINK Project – THINK is a project financed by the European Commission (DG Energy) that advises the Commission on a diverse set of mid- and long-term energy policy topics. The project is organised around a multidisciplinary group of 23 experts from 14 countries covering five dimensions of energy policy: science and technology, market and network economics, regulation, law, and policy implementation.

Source: THINK project

TOOT Methodology – “Take Out One at the Time” methodology consists of excluding investment items or complete projects from the forecasted network structure on one-by-one basis and to evaluate the load flows over the lines with and without the examined network reinforcement.

Source: ENTSO-E, ENTSO-E Guideline for Cost Benefit Analysis of Grid Development Projects, section 3.6.4, page 28, draft 12 June 2013

Transmission (electricity) – ‘transmission’ means the transport of electricity on the extra high-voltage and high-voltage interconnected system with a view to its delivery to final customers or to distributors, but does not include supply.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/72/EC

Transmission (Natural Gas) – ‘transmission’ means the transport of natural gas through a network, which mainly contains high-pressure pipelines, other than an upstream pipeline network and other than the part of high-pressure pipelines primarily used in the context of local distribution of natural gas, with a view to its delivery to customers, but not including supply.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/73/EC

Transmission System Operator (TSO) for Electricity – ‘Transmission system operator’ means a natural or legal per[-]son responsible for operating, ensuring the maintenance of and, if necessary, developing the transmission system in a given area and, where applicable, its interconnections with other systems, and for ensuring the long-term ability of the system to meet reasonable demands for the transmission of electricity.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/72/EC

Transmission System Operator (TSO) for Natural Gas – ‘Transmission system operator’ means a natural or legal person who carries out the function of transmission and is responsible for operating, ensuring the maintenance of, and, if necessary, developing the transmission system in a given area and, where applicable, its interconnections with other systems, and for ensuring the long-term ability of the system to meet reasonable demands for the transport of gas.

Source: Single market for gas and electricity » EU Third legislative Package: DIRECTIVE 2009/73/EC


Voltage – Unless stated otherwise,Voltage refers to the root-mean-square value of the positive sequence of the phase-to-phase voltages at fundamental frequency.

Source: ENTSO-E


White Paper – Commission White Papers are documents containing proposals for Community action in a specific area. In some cases they follow a Green Paper published to launch a consultation process at European level. When a White Paper is favourably received by the Council, it can lead to an action programme for the Union in the area concerned.

Source: European Commission



    1. Energy Transition 2.0 Europe

      April 29
    2. European Electric Vehicle Batteries Summit

      June 3 - June 4
    3. 2nd Annual Europe Solar + Energy Storage Congress (ESES)

      June 23 - June 24
    4. International Flow Battery Forum

      June 30 - July 2
    5. SolarPower Summit 2020

      September 29