Energy Carrier of Unlimited Potential?

Hydrogen Is the Most Abundant Element in the Universe – and It Is Very Rich in Energy

Highly developed industrialized countries such as Germany require a clean, safe, and affordable power supply – the energy crisis shows this very clearly. Hydrogen might contribute to the solution, being the most abundant chemical element in the universe. It offers virtually unlimited potential as a carrier of energy.

This requires, however, that renewable energy be in sufficient supply for the production of sustainable “green” hydrogen, which does not exist as a natural gas, but must be produced from water or biomass by means of an energy-intensive process. “Hydrogen is a carrier of energy, not an energy source and thus rather comparable to electricity,” says Professor Thomas Jordan of KIT’s Institute for Thermal Energy Technology and Safety. In contrast to electric current, however, it is quite easy to store. “Electric current and hydrogen are very closely associated with each other via electrolysis and energetic reconversion. This means that electricity can be stored in the form of hydrogen to be reconverted later to electric current or heat upon demand,” the hydrogen expert explains. The whole energy system will become more flexible and robust.


Titelseite von lookKIT: Im Vordergrund der Schriftzug „Wasserstoff“, im Hintergrund grafische Darstellungen von Wasserstoff-Molekülen in Blau. modus: medien + kommunikation gmbh

Issue 4/2022 of the research magazine lookKIT focuses on the versatile element.


Thus, hydrogen not only powers fuel cells, but it is also suitable for the efficient, climate-neutral operation of internal combustion engines. In addition, solar energy harvested during the summer could reduce the dependency on oil, coal, and gas in winter. Green hydrogen can further be used in the chemical industry as a sustainable resource for the synthesis of various substances, such as methanol or ammonia, the latter being required for the production of nitrogen fertilizer. “Hydrogen produced by electrolysis with green current is hence at the core of the power-to-X technologies for storing surplus electricity in times when the production of wind or solar energies exceeds the demand.

The CO2 footprint of various products can be reduced dramatically in this way,” emphasizes Jordan. “Hydrogen technologies make it possible to combine the energy, industrial, and transport sectors, to optimize them, and to make them sustainable,” explains Thomas Hirth, Vice President for Transfer and International Affairs at KIT. “To cope with the energy transition, we should exploit the full potential of hydrogen. At KIT, we want to demonstrate that this is feasible and how it is done.”


Blick in eine Pilotanlage zur Herstellung synthetischer Kraftstoffe. Amadeus Bramsiepe, KIT
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Professor Roland Dittmeyer and Dr. Frank Graf talk about the challenges of establishing a hydrogen economy.

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Prototypes of Hydrogen Cars and Aircraft Already in the 1970s

This insight is not exactly new: Hydrogen was discovered as early as in 1766 by the English chemist Henry Cavendish and it was named by Antoine Lavoisier in 1787. The founder of modern chemistry realized that the combustion of this energy-rich gas produces water and thus called it “hydrogène” in French, derived from the Latin word “hydrogenium”, which means “water-forming substance”. In the first half of the 20th century, hydrogen was produced from gasified coal and added as a major component to the gas mixture used for street lighting and the heating of houses in the city gas network of the Ruhr industrial area in Germany.

The significance of hydrogen for mobility was recognized especially during the energy crisis of the 1970s. In order to reduce the dependency on oil imports, prototypes of hydrogen-operated road and rail vehicles as well as aircraft were developed, among others, by KIT’s predecessor institutions. “A drive concept for a hydrogen bus with a fuel cell was developed at the then Kernforschungszentrum Karlsruhe,” Jordan says. Major car manufacturers started producing and promoting small series of hydrogen-powered cars – often subsidized by public funds. “In many cases, these concepts were buried in the files, as this technology was considered too expensive,” states the hydrogen expert. The challenges driven by the climate crisis and by gasoline prices of more than two euros per liter have changed this perception.

Green Hydrogen: a Scarce Resource

One problem is that green hydrogen is in short supply: “The hydrogen economy distinguishes between green hydrogen from renewable sources such as the sun, biomass, or wind, and gray hydrogen produced from fossil raw materials,” explains Jordan. Even today, large quantities of hydrogen, namely about 120 million tons per year, are produced worldwide for commercial purposes. “Admittedly, more than 99 percent of this is gray hydrogen produced with an enormous ecological footprint: The emissions amount to ten tons of climate-harmful CO2 per ton of hydrogen produced.”

A substantial proportion is caused by the petrochemical industry where the hydrogen obtained is immediately used for refining oil into gasoline, diesel, or kerosene. “We see that there is a great CO2 reduction potential by replacing conventionally produced hydrogen with green hydrogen,” concludes Jordan. The scientist complains that a hydrogen-friendly legislation that could promote progress on the “royal road” to green hydrogen production using green current and electrolysis is still missing in Germany. Another problem besides the required quantities of suitable electricity is the lack of capacities for electrolysis-based hydrogen production.

Infrastructure Expansion Is Linked with Some Challenges

Safety aspects might be another obstacle, even though handling of hydrogen is not automatically more dangerous than handling other energy carriers such as gasoline or electricity, Jordan emphasizes. Hydrogen produced at decentralized locations using renewables, or in other countries where sun and wind are abundant, might be transported safely using existing gas pipelines, or in liquefied form on ships like CNG. “Here, the experts are already working on a solution to make transport to Germany and within the country safer,” says Jordan who has been doing research on the safe use of hydrogen for many years.

However, distribution to private consumers is not widespread yet: Due to its low specific weight, the storage and transport of hydrogen require a lot of space, ultra-low temperatures, or high pressures of up to 1000 times ambient pressure. So far, only 100 hydrogen filling stations offering compressed hydrogen exist all over Germany – one of them used for refilling two hydrogen-operated shuttle buses can be found at KIT. “Cryogenic or liquefied hydrogen is not available yet at any of these public filling stations,” Jordan says. Big storage tanks, which would be required for large-scale distribution via filling stations, are also rarely found.

Jordan points out that upscaling the hydrogen economy also means that technical laypersons would have to handle hydrogen. Whether during refilling the car or in the basement at home where electric current generated via fuel cells or cogeneration can be fed into the grid upon demand – consumers would have immediate contact with the new energy carrier. This entails an even better understanding of the behavior of hydrogen in case of everyday accidents. Jordan also calls for fault-tolerant technologies, the greatest possible transparency, and comprehensive communication to accompany the extension of the technical infrastructure: “Hydrogen not only requires acceptance, but also trust.”

Felix Mescoli, January 18, 2023

Alt-Text: Ein weißer VW-Bus wurde umgebaut: Auf der Ladefläche liegen Gasflaschen, es sind außerdem Schläuche und Kabel zu erkennen, hinter denen sich die Brennstoffzelle verbirgt. Kernforschungszentrum Karlsruhe / KIT
A hydrogen test vehicle from 1986. Fuel supply and part of the fuel cell can be seen on the truck bed.
Schwarz-Weiß-Bild einer Versuchsanlage, die wie ein kleiner Turm aussieht. Kernforschungszentrum Karlsruhe / KIT
At the Kernforschungszentrum Karlsruhe, a predecessor of KIT, research on hydrogen was carried out early on. This experimental facility from the 1970s was built as part of nuclear fusion research.
Thomas Jordan im Gespräch. Riccarodo Prevete, KIT
Thomas Jordan's research at KIT includes safety issues related to the use of hydrogen.
Blick von Oben auf das Energy Lab. Markus Breig / Jonas Zilius, KIT
At the Energy Lab 2.0 on Campus North of KIT, the Energiewende is being researched in a hands-on manner. Green hydrogen can contribute to the climate-neutral energy supply of the future.