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What happened to LOHC - Special oil stores hydrogen

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In the future, hydrogen will power cars, aircraft and ships, heat houses and make steel production more sustainable. But storing the energy carrier of the future in pressurized or liquid tanks is expensive. A company from Erlangen therefore wants to chemically tame hydrogen. A workshop in Erlangen, it belongs to the young company Hydrogenious. Chief engineer Caspar Petz is standing in front of a gray container with high-tech in it, which is soon to be delivered to Finland: "Here you see our commissioning team, and here our automation engineers, who take care of the software".

An employee sits in front of his laptop and analyzes measured values. Inside the container, his colleague inspects a tangle of pipes connecting various tanks and reactors. Time is pressing, and soon the plant is to embark on its journey to Northern Europe, explains Caspar Paetz: "It will supply a hydrogen filling station in Finland with hydrogen. The tests will probably be completed in three weeks. And then it will be delivered".

The vision: efficient hydrogen storage
The plant in the grey container is used to store hydrogen. Usually the gas is stored in pressure tanks or liquefied at minus 250 degrees Celsius. But both are very expensive and not very efficient, says Caspar Paetz. His company is therefore developing a new concept: hydrogen is stored chemically - with the help of so-called LOHC.

"LOHC" stands for Liquid Organic Hydrogen Carriers, translated: liquid organic hydrogen carriers. We take hydrogen and bind it chemically to this carrier liquid. And this carrier liquid is an oil. It can be stored and transported like any other oil."

A special oil serves as a carrier fluid
The idea has been around in the professional world for decades. But there was a lack of a suitable oil. But in 2009, a doctoral student at the University of Erlangen took up the cause. His name: Daniel Teichmann, says Caspar Paetz: "He identified organic carrier fluids that are very well suited for commercial use on large scales. We are still working with these carrier fluids today".

In 2013 Daniel Teichmann founded the company Hydrogenious. In addition to the right oil, other factors also play a role - suitable catalysts, for example, reaction accelerators. One is needed to bind the hydrogen to the oil. Another is needed to get it out of the oil, explains Hydrogenious chief engineer Paetz.

"This is the actual core area of our technology. It releases the hydrogen in very high purity and does not destroy the carrier fluid. Because if we were to destroy it, we would have to constantly replace it, and nothing would be gained.

To release the hydrogen again takes a lot of energy.
The special oil can be loaded and unloaded several hundred times with hydrogen, says Paetz, and only then does it need to be replaced. But there is one shortcoming: To get the stored hydrogen out of the oil, high temperatures are needed, which means a lot of energy.

"That's about a third of what I generate in the form of hydrogen afterwards. We offer various technical concepts for this: Either the energy is provided in the classic way via electricity, preferably regenerative, of course. But we can also burn part of the hydrogen we produce in special burner units to provide this energy. Then we have a self-sufficient system that doesn't need an additional connection.

Instead, heat is released when the hydrogen is stored - heat that can be used for heating, for example. The great advantage of the technology is the storage density, emphasizes Caspar Paetz: "That is about a factor of five. We can store five times as much hydrogen in the same volume as with printing technology.

The storage density is five times higher than with pressure tanks
In numbers: To store one kilogram of hydrogen, it has so far taken a pressure bottle as large and heavy as a human being. With LOHC technology, a portable 20-liter canister is sufficient. Although the energy balance is more favorable for pressure storage, and it is advantageous when relatively small quantities are transported over distances that are not too long, the energy balance is still very good. But with large quantities and long transport routes, the LOHC technology is more economical, says Caspar Paetz. Because the storage oil can be transported in a space-saving way with ordinary tankers, or also with trains and ships.

Hydrogen transport thus seems to be the most interesting field of application for the technology. Caspar Paetz describes a possible application scenario as follows: "I have a source. There I can provide five to ten tons of hydrogen per day, store it in the material and distribute it from there to several consumers, for example filling stations for bus fleets, which each need one to two tons per day".

"There is a growing interest in our technology"
At each filling station there is then a unit like the one in Erlangen, which takes the hydrogen out of the oil again. First pilot plants are already installed. Each day they can handle a few dozen or even a few hundred kilograms of hydrogen. But now Hydrogenious is planning much larger plants, with capacities of several tons. The signs are obviously good for Paetz and his people. Because in politics the topic of hydrogen is currently in high demand, knows Caspar Paetz: "We do not only have a national hydrogen strategy. We also have our own Bavarian hydrogen strategy. There is a growing interest in our technology, but also in the topic of hydrogen in general".

But Hydrogenious still has some homework to do: In addition to upscaling the plants, the focus is on catalysts, among other things. These are to become more efficient and thus more economical. And meanwhile other companies are also working on the technology: Munich-based start-up H2-Industries, for example, has announced the development of a fuel-cell-powered barge in which hydrogen is stored in special oil.

Original German article could be found here:

Tolle Idee! Was wurde daraus? - Spezialöl speichert Wasserstoff (deutschlandfunk.de)

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