WaHydrogen Glossary
The world of hydrogen is rife with technical terms, definitions, and abbreviations, as well as physical and chemical expressions, economic indicators, and regulatory jargon.
In the hydrogen glossary, you'll find definitions and explanations of the individual terms.
Bipolar PlateBipolar plates (BPP) are considered a key component in hydrogen technologies. They are used in both fuel cell and electrolysis stacks for hydrogen production. They have a significant impact on the efficiency and performance of hydrogen systems. The three most important(...)
Fuel CellA fuel cell (FC) is a technical device that, as an electrochemical energy converter, directly converts hydrogen into electrical energy without combustion. Due to its efficiency and versatility, the fuel cell is considered a promising technology for (...)
Carbon ManagementThe term "carbon management" encompasses strategies and technologies for controlling, storing, and utilizing carbon dioxide (CO₂). Carbon management is divided into two areas: Carbon Capture and Storage (CCS) and Carbon Capture and Utilization (CCU, (...)
Chlor-alkali electrolysisChlor-alkali electrolysis is an industrial process for the simultaneous production of chlorine, caustic soda, and hydrogen from table salt and water. Chlor-alkali electrolysis is an industrial process for the simultaneous production of chlorine, caustic soda, and hydrogen from(...)
CO2 Carbon dioxide, or CO₂ for short, is a colorless, odorless gas that plays a key role in the Earth's atmosphere. It is a natural component of the air and is central to the planet's carbon cycle. The CO₂ concentration in the atmosphere is approximately 0.04(...)
Steam reformingSteam reforming is the most important industrial process for producing hydrogen from carbon-containing energy sources. The hydrogen produced in this way is referred to as gray hydrogen. The method (also known as steam reforming or steam reforming)(...)
Direct Air CaptureThe term “Direct Air Capture” (DAC) refers to chemical and engineering processes for capturing carbon dioxide (CO₂) from the ambient air. This technology plays an important role in climate protection strategies and the decarbonization of various economic sectors; it is currently (...)
Direct ReductionDirect reduction (also known as sponge iron production) is a relatively new process for producing iron that is considered a key technology for decarbonizing the steel industry. Unlike the conventional blast furnace route, direct reduction involves reducing iron ore directly using natural gas, (...)
E-FuelsE-fuels are synthetic fuels produced using renewable electricity. The term encompasses a wide range of products, such as e-methanol, e-diesel, e-gasoline, e-naphtha, and e-kerosene—the latter also known as Sustainable Aviation Fuels (SAF). Since(...)
ElectrolyzerAn electrolyzer is a piece of equipment that splits water into its components, hydrogen and oxygen. This splitting process occurs by passing an electric current through the water. Electrolyzers are key components in hydrogen production,(...)
European Hydrogen BackboneThe European Hydrogen Backbone (EHB) is an initiative by European gas network operators to establish a Europe-wide hydrogen transportation network. Launched in 2020 by 31 European gas network operators, the project aims to connect industrial clusters, ports, and hydrogen valleys into a(...)
Explosion ProtectionExplosion protection encompasses all measures taken to prevent explosions. This is particularly important in hydrogen facilities, as hydrogen forms an explosive gas mixture with air and therefore requires special safety precautions. Explosion protection is divided into primary, (...)
Colors of HydrogenThere is a whole range of hydrogen “colors.” The color provides information about the hydrogen’s production method and carbon footprint; however, there is no uniform international or cross-industry definition of these colors. Some hydrogen colors have the same meaning, while (...)
H2-ready power plantsGas-fired power plants designed for future operation with hydrogen are referred to as H2-ready power plants. These plants can initially be operated with conventional natural gas and later, either partially or entirely, with hydrogen. How They Work The basic principle is similar to that of (...)
The chicken-and-egg problemThe chicken-and-egg problem of hydrogen deployment describes the interdependence between the development of hydrogen infrastructure and the demand for hydrogen, which hinders the expansion of the hydrogen economy. Chicken-and-egg problem: Explanation The development of a(...)
Import StrategyThe German federal government’shydrogen import strategy defines the political and economic framework for importing hydrogen and its derivatives into Germany. The Federal Cabinet of the “Ampel” coalition adopted it on July 24, 2024, to achieve the goals of the National (...)
IridiumIridium is a chemical element that belongs to the platinum group of metals and is one of the rarest elements in the Earth's crust. This precious metal occurs naturally only in very low concentrations, which is why it is much rarer. As a result, iridium is more valuable than gold and platinum. The(...)
Nuclear Energy vs. HydrogenThe debate over the right energy source for the future is hotter than the inside of a nuclear reactor. In one corner is nuclear energy; in the other, hydrogen, which is hailed as the “wunderkind” of renewable energy. Both are very exciting technologies, and if (...)
Core NetworkThe Hydrogen Core Network is the planned high-pressure pipeline infrastructure for transporting hydrogen in Germany. It is intended to enable the cost-effective and widespread use of hydrogen, thereby laying the foundation for a hydrogen economy in Germany. The(...)
Climate Protection AgreementsClimate Protection Contracts (Carbon Contracts for Difference, CCfD) are a subsidy instrument developed by the former "Ampel" coalition to support industrial transformation. They aim to make climate-friendly production processes economically attractive and to (...)
Membrane-Electrode AssemblyThe membrane-electrode assembly, also known as an MEA (Membrane Electrode Assembly), is the electrochemical core of PEM fuel cells and many types of electrolysers. It consists of a proton-conducting membrane with catalyst layers and gas diffusion layers on both sides (...)
National Hydrogen StrategyA national hydrogen strategy defines the policy framework for developing a hydrogen economy in a country. More than 40 countries worldwide have already published such strategies. The strategies differ in their specific objectives and priorities, (...)
National Hydrogen CouncilThe National Hydrogen Council (NWR) is an advisory body to the federal government. It was established in 2020. Its mission is to support the implementation and further development of the National Hydrogen Strategy (NWS). The development of a hydrogen economy represents a(...)
PFASPer- and polyfluoroalkyl substances (PFAS for short) are a group of more than 10,000 synthetic chemicals. These compounds are characterized by an extremely stable carbon-fluorine bond. PFAS are characterized by the following properties: Water- and grease-repellent and(...)
Power-to-XPower-to-X (PtX) refers to technologies that convert excess electricity from renewable energy sources into chemical energy carriers and raw materials. The key process involved is electrolysis, in which water is split into hydrogen and oxygen using electricity. The resulting (...)
RED II/RED IIIThe Renewable Energy Directives (RED) II and III constitute the European Union’s central regulatory framework for promoting renewable energy. The directives are part of the European Green Deal, which was adopted at the end of 2019, and play a key role in the transformation of (...)
RFNBO (Renewable Fuels of Non-Biological Origin)Renewable fuels of non-biological origin, or RFNBO (Renewable Fuels of Non-Biological Origin) for short, are a key component of the European Union’s decarbonization strategy. The term refers to renewable energy sources that are not derived from biomass. As(...)
OxygenOxygen is one of the most abundant chemical elements on Earth and makes up 21 percent of the Earth's atmosphere. The gas, with the element symbol O, usually occurs in nature as a diatomic molecule (O₂). This colorless, odorless gas is characterized by its high(...)
Sector Integration Sector coupling refers to the systematic interconnection and integration of the electricity, heating, and mobility sectors, as well as industrial processes, with the goal of increasing the efficiency and flexibility of the overall energy system and maximizing the share of renewable energy. (...)
Safety valveSafety valves are critical safety devices in hydrogen systems that open automatically when defined pressure limits are exceeded and release gas in a controlled manner. They are essential for the safe operation of electrolysers, storage facilities, pipelines, and refueling stations. For H₂ applications(...)
StorageHydrogen storage is crucial for the energy transition. It allows for a balance between production and consumption. Thanks to their high capacity, hydrogen storage facilities can offset seasonal fluctuations in renewable energy and bridge supply gaps. Storage facilities are therefore (...)
Synthesis gasSynthesis gas is a mixture of hydrogen and carbon monoxide (H₂/CO) and is an important intermediate product in the chemical industry. It is produced by steam reforming of natural gas, partial oxidation of hydrocarbons, or gasification of biomass or coal. The H₂/CO ratio (...)
GHG quotaThe Greenhouse Gas Reduction Quota, or GHG Quota for short, is a market-based climate protection tool that was introduced in Germany in 2015. It aims to increase the share of renewable energy in the transportation sector and thereby reduce greenhouse gas emissions. The GHG Quota replaced the previous (...)
TransportationTransporting hydrogen is a key challenge for the development of a global hydrogen economy. There are various transportation options for delivering hydrogen from the production site to the consumer. Generally, there are four types of (...)
HydrogenWith a mass fraction of about 70 percent, hydrogen is the most abundant chemical element in the universe. It is also the lightest element in the universe. It consists of one proton and one electron. Under normal conditions, it exists as a colorless, odorless gas and does not (...)
Hydrogen BankThe European Hydrogen Bank is a key EU instrument for promoting the hydrogen economy. It is designed to lower the production costs of green hydrogen and provide investment certainty. It is not a traditional bank, but rather a funding mechanism of the (...)
Hydrogen EmbrittlementHydrogen embrittlement is a mechanism of material damage in which hydrogen penetrates materials and degrades their mechanical properties. The damaging effects vary greatly depending on the material used. This phenomenon is considered a key challenge in (...)
