Glossary

  
Balancing PowerAvailable at short notice, this energy is produced in highly dynamic power plants like gas turbine or pumped storage hydroelectric power plants. It is needed to stabilise the voltage and the frequency of the grid when there is a short and unpredicted power deficit or surplus.
Base LoadThe constant electricity demand during 24 hours of a day. Base load is being covered by lignite or nuclear power plants.
Biomass GasificationConversion of (solid) biomass into hydrogen rich gases (synthesis gas or shorter syngas). Main components are methane, hydrogen, carbon monoxide and carbon dioxide. The overall composition is strongly dependant on the gasification technology.
Carbon Dioxide

Abbreviation CO2. Is a product of the complete combustion of carbon or carbon rich compounds. It is non-toxic, colour- and odourless. Necessary for photosynthesis, but also main reason for the man-made greenhouse effect. About 22bn tons are emitted worldwide every year.

Carbon Monoxide

Abbreviation CO. Is a product of the incomplete combustion of carbon or carbon rich compounds. It is toxic, colour- and odourless. Can be used in high-temperature fuel cells and is a component of syngas or towngas.

CHPCombined Heat and Power
Cogeneration-> Cogeneration Plant
Cogeneration Plant

Decentralised plant for the combined production of electricity and heat. Electricity is being produced with a generator or a fuel cell, the lost heat can be used by a heat exchanger. The underlying principle is that of CHP.

Combined Heat and Power

Abbreviation CHP. The combined production of electricity and heat in one power plant. Not only the mechanical work is being utilized (as in every other power plant) but also the heat that is inevitably produced.

Condensing Boiler

Boiler that cools down the fumes to the point where the contained water vapour condenses and the resulting heat can be used.

Cryogenic Hydrogen Tank

Storage device for the storage of liquid, very cold hydrogen. Works similar to a thermos flask with a metal container inside and one outside. The inner side is insulated with metal foil and glass wool and the space between inner and outer container is, in addition, evacuated.

DMFC

Direct methanol fuel cell. Converts directly liquid methanol into electricity; function and materials are similar to that of a PEFC. The efficiency is relatively low (ca. 35%), but its dimensions can be made very compact.

Ecological Footprint

The entire ecological consequences according to a Life Cycle Assessment.

Efficiency

Ratio of usable energy to invested energy, or likewise ratio of invested primary energy and usable electricity.

Efficiency

Ratio of necessary input energy to gained output energy of an energy conversion system. The figure is used to assess the efficiency/profitability of a technical process. Due to unavoidable losses, like friction or heat, this figure is always below 1. It is also often expressed in percent.

Elektrolyser

The device to use electrolyis. It consists mainly of two electrodes, separated by a membrane, at which the gases (hydrogen and oxygen) form.

Elektrolysis

The separation of bonded chemical elements can be used for the water-electrolysis where by means of an electric current water is being split into its compounds hydrogen and oxygen.

Energy Carrier

A system which energy content can be utilised in technical conversion processes. The energy carrier can be gaseous (e.g. hydrogen, natural gas), liquid (e.g. petrol) or solid (e.g. coal), but also be of a non-apparent nature such as electric current or sunlight.

Energy Density

The energy content of an energy carrier based on a mass or volumetric unit.

Energy Exchange

Electronic exchange for electricity. The European Energy Exchange (EEX) in Leipzig, Germany, covers both spot and futures market.

European Electricity Grid

The sum of all electricity grid lines in Europe. To secure a constant voltage and supply all members of the UCTE form a joint grid management.

Flywheel

For storing energy for a short period of time. Electrical energy drives, through an engine, a flywheel which saves this mechanical energy as kinetic energy. It can then be re-extracted with a generator at high efficiencies.

Fossil Fuels

Fuels like natural gas, coal or crude oil all derive from geological processes of organic/biological material. Their combustion and the resulting emission of carbon dioxide is a main contribution to the man-made greenhouse effect.

Fuel Cell

Reverse process of electrolysis. Hydrogen or hydrogen rich substances are converted into electricity and heat under presence of oxygen. It has a high efficiency as combustion is avoided.

Futures Market

Market place for energy tradings with delivery in weeks, months or years. Usually for the long-term planning of energy supply. In contrast to the spot market it comprises a real, physical trade.

Gas Turbine Power Plant

Is used for generating energy on short notice. Hot, compressed exhaust fumes from a combustion are used to drive a turbine which then transmits its rotation onto a power generator.

Gas-Steam Power Plant

Combination of a gas and a steam turbine power plant for power generation on short notice. The gas turbine drives a power generator with hot fumes, then these fumes are used for producing steam. This steam can then be used to drive a steam turbine, which drives a power generator. This system can gain high efficiences up to 60%.

Green HydrogenHydrogen which is produced from renewable energies.
Greenhouse Effect

Natural Greenhouse Effect: When sunlight hits the surface of the earth it is being reflected as thermic radiation. This radiation gets absorbed by water vapour and trace gases (carbon dioxide CO2, nitrous oxide N20, ozone 03) in the atmosphere. Without this retention the mean temperature on earth would not be 15C, but about 33C lower.


Anthropogenic Greenhouse Effect: Global temperature rise due to additional, man-made emissions of greenhouse gases, mainly carbon dioxide from burning fossil fuel and CFCs.

Greenhouse Gases

Water vapour and trace gases (carbon dioxide CO2, nitrous oxide N20, ozone 03, methane CH4, CFCs etc.) in the atmosphere which can cause the greenhouse effect.

Grid stability

Grid frequency and voltage have, due to physical reasons, only a low tolerance of fluctuations. Therefore, electricity production and demand need to be balanced at any time to ensure a stable grid.

Higher Heating ValueChemical energy content of a fuel.
Hydrogen

Lightest of all chemical elements. Odourless, colourless, non-toxic; high diffusibility; boiling point -259.2C; ignition limits in air 4.0-75.0 Vol.%

Hydrogen Storage

Either possible as compressed hydrogen (CH2) in tanks at 200 bar and up to 700 bar in the near future, or as liquid hydrogen in cryogenic tanks, or as metal hydride.

Idle Power

Part of the DC-power which is needed to build up the electro-magnetic field. It occurs when electric current and voltage are out of phase (e.g. from inductivities or capacities). It cannot be used by the end-user and only loads the grid.

Life Cycle Assessment

Assessment of the environmental damage of processes, installations, energy supply systems etc. Usually assessed according to the international standards DIN/ISO 14040 et sqq.

Liquid Hydrogen

In order to increase the storage density hydrogen can be liquified. It is then called LH2 (Liquid/Liquefied Hydrogen) and has to be stored and transported at -253C (-423F) in cryogenic tanks. Liquification is very energy-consuming and needs about one third of the energy content of the liquid hydrogen.

LoadThe electrical power taken from the grid.
Lower Heating Value

The result of subtracting the latent heat of water vapour in the exhaust fume from the higher heating value. This value was introduced when there was no technology available to use the heat that is contained in the vapour and the calculated efficiencies (using the higher heating value) were rather low.

MCFC

Molten Carbonate Fuel Cell. High temperature fuel cell with operating temperatures of 650C. Uses liquid alkaline-carbonates as an electrolyte and hydrogen, natural gas and others as fuelling gas. It can be deployed in the medium performance range (e.g. stationary CHP). 

Medium Load

The fluctuating energy demand that exceeds the constant base load during the day. Medium load is usually provided by coal and gas fired power plants.

Metal Hydrides

Metal alloys which can absorb gaseous hydrogen like a sponge absorbs water. The resulting metal-hydrogen-compounds offer a high storage density, safe handling, and the hydrogen can easily be extracted under slightly higher ambient pressure.

MinutereserveThe power output of a power plant that can be activated within 1 to 5 minutes.
Osmosis

Autonomous interaction of two aqueous solutions with different concentrations, separated by a semi-permeable membrane. During reverse-osmosis it needs energy to force this process against the natural concentration gradient.

PAFC

Phosphoric Acid Fuel Cell. Low temperature fuel cell with operating temperatures of 200C. Uses a phosphorus-acidic gel as an electrolyte and hydrogen, natural gas and others as fuelling gas. Relatively tolerant against carbon monoxide. It is being commercially deployed in CHPs.

Peak Load

High energy demand at very short notice. Needs to be covered within seconds to minutes, usually by highly dynamic power plants like gas turbine or pumped storage hydroelectric power plants.

PEFC (PEM-FC)

Polymere Electrolyte Fuel Cell. Also known as PEM-FC (Proton Exchange Membrane Fuel Cell). Low temperature fuel cell with operating temperatures of 80-100C. Uses a polymere membrane as an electrolyte and hydrogen, natural gas and others as fuelling gas. It can be deployed for mobile applications or in private homes.

Pressurized Air Storage

Electro-mechanical storage solution where air is compressed with electrical energy and can then be released again to drive a power generator.

Primary EnergyThe state in which energy occurs in nature.
Primary Energy Carrier

This includes all the natural resources like natural gas, crude oil, coal, uranium, solar radiation, windpower, hydropower and geothermal energy.

Pumped Storage Power Plant

Hydroelectric power plant to produce peak load electricity. Electrical energy is being stored as potential energy by pumping water from a lower basin to a higher basin. When needed, water can be released, passing the turbines on its way down and thereby producing electricity through the attached generators.

Reformation

Chemical conversion process, for example to produce hydrogen from natural gas, coal or other hydrocarbons. Often in presence of a catalyst and at higher temperatures. See also steam reformation.

Renewable Energies

Solar, wind or geothermal energy, hydropower, biomass, tidal energy and others are called renewable as they are abundantly available and never deplete.

Secondary Energy

Energy that is being produced by technically converting other forms of energy. For instance, it can derive from primary energy through a single conversion step (solar radiation to electricity in a PV-panel) or through multiple steps from other forms of secondary energy (hydrogen from electrical energy through electrolysis). This conversion comes always with energy losses.

Secondary Energy Carrier

Energy carrier for which production other energy was needed, e.g. electricity, hydrogen or petrol.

Shift-Reaction

Exothermal, catalytic reaction of carbon monoxide (from syngas) with steam to carbon dioxide and hydrogen. It forms the second step during steam reformation.

SOFC

Solid Oxide Fuel Cell. High temperature fuel cell with operating temperatures of 900-1000C. Uses a solid, ceramic material which transmits oxygen ions as an electrolyte and hydrogen, natural gas, biogas and others as fuelling gas. It can be deployed in stationary CHP.

Spot Market

Market place for energy tradings with delivery on the following day. Usually for the short-term compensation of erroneous demand forecasts.

Standard Cubic Metre

Nm3 , also often written as Nm3;

Means the amount of gas contained in one cubic metre at an absolute pressure of 101.325 kilopascals (1013,25 mbar), a humidity of 0% and a temperature of 0C (DIN 1343), 15C (ISO2533), or 20C (industries using pressurized air) respectively.

Steam Reforming

Endothermic conversion of hydrocarbons (e.g. natural gas, biogas, also liquid hydrocarbons like diesel etc.) by means of adding steam at high temperatures. The result is a syngas (see biomass gasification) of carbon monoxide (CO), methane (CH4) and hydrogen (H2).

Steam Turbine Power Plant

Similar to gas turbine power plants hot steam is used to drive the turbine which is attached to a power generator.

System Pertubation

Pertubations in the grid caused by electrical consumers or decentralised producers, e.g. elevated idle power or frequency overtones.

UCTE

Union for the Co-ordination of Transmission of Electricity. Formerly known as UCPTE (L'Union pour la Coordination de la Production et du Transport de L'Electricit) the UCTE is responsible for co-ordinating the transmission of electricity in the European electricity grid.

Wind-Hydrogen-System

Consists of the following components:

a) wind turbine to produce power
b) electrolyser to produce hydrogen
c) hydrogen storage
d) fuel cell system to convert the hydrogen back to electricity