Glossary

In a fuel cell, the chemical bond energy of hydrogen and oxygen is released through the combination of the two elements. It is essentially the reverse process of an electrolyzer. The result is an electrical voltage that can then be utilized. This process is not "combustion" in the traditional sense; rather, it is often referred to as "cold combustion" since no flames are produced—only electrical energy.

Currently, the hydrogen used in Germany is produced through the use of steam reformers. In this process, natural gas is broken down into its components by adding hot steam. This produces hydrogen and nitrogen, but also climate-damaging carbon dioxide. The hydrogen produced this way is known as "grey hydrogen."

An electrolyzer is a device in which a chemical reaction is induced using electrical current. In our context, this refers to water electrolysis, where water is split into hydrogen and oxygen. If the electricity used comes from renewable energy sources, the resulting hydrogen is referred to as green hydrogen. There are different types of water electrolysis. In the GET H2 Nukleus project, the construction of a PEM electrolyzer is planned. PEM stands for Proton Exchange Membrane. In a PEM electrolysis process, no additional chemicals are added.

Whoever wants to produce hydrogen using renewable electricity is obligated to prove that the energy used is indeed renewable. This is done through so-called guarantees of origin, which are linked to specific criteria.

Liquid Organic Hydrogen Carrier (LOHC) are liquid organic substances with the ability to store hydrogen. In such a carrier, hydrogen can be stored — with the thermal oil benzyltoluene for example, that's up to 54 kilograms of hydrogen per cubic meter of LOHC. The LOHC can be transported safely and without special cooling by tanker truck, train, or tanker ship. At the destination, the hydrogen is released from the LOHC in a dehydrogenation unit and then used. The thermal oil used as LOHC can be loaded and unloaded with hydrogen hundreds of times after the hydrogen is released and is recyclable.

EU legislation regulates which hydrogen is classified as green. This involves not only the origin of the electricity—whether it comes from wind turbines or other sources—but also factors such as the timing between the generation of renewable electricity and its consumption in an electrolyzer. Only hydrogen that meets these criteria and is classified as green can be counted towards CO2 reduction.

Also known as synfuels, synthetic fuels are typically artificially produced fuels where the traditional crude oil base is replaced with other, more environmentally friendly alternatives. The latest and most climate-friendly form of these fuels are called e-fuels. In the production of e-fuels, renewable electricity, hydrogen, and CO₂ captured from the air are used to create climate-neutral fuel.