How to use hydrogen, not oil, to power the economy

To achieve climate neutrality by 2050, Germany will need low-emission – if not zero-emission – solutions for transportation and industry. As part of a Kopernikus initiative called P2X, researchers are developing ways to safely store hydrogen in containers in atmospheric conditions. They use liquid organic hydrogen carriers, also known as LOHCs, which bind hydrogen reversibly and allow the subsequent separation of carrier material and gas through a special dehydrogenation unit. It is the only method for efficiently discharging this liquid storage. At the same time, however, the hydrogen needs to be upgraded to fuel cell quality.

Ellen Gapp, a young researcher working at Karlsruher Institut für Technologie, better known as KIT, turns on the faucet. Hydrogen starts immediately flowing from the LOHC pilot system into an aluminum-coated gas sampling bag (see fig. 1). She says both fuel cell buses and passenger cars need high-purity hydrogen. The LOHC color is what makes all the difference: One of the two bottles in front of her contains a clear and transparent liquid, still charged with over 97 percent hydrogen. The content of the other has turned slightly orange, as some of the gas has already been released and the state of charge is down to 80 percent (see fig. 2).

The aim of the Kopernikus’ Power-to-X project is to investigate alternative approaches to storing clean power in chemical compounds. In the first project stage, which lasted for three years, the researchers analyzed a wide variety of storage options. This included ways to store electrolytic hydrogen in LOHCs and create synthetic fuels, such as synthetically produced kerosene, diesel, natural gas and gasoline and dimethyl ether, a diesel substitute. Now in its second stage, the project is focused on a more limited number of options, namely LOHCs and synthetic kerosene, diesel and gasoline.

High storage density

The project seems to have been launched at just the right time. LOHCs are a perfect fit for Germany’s recently published national hydrogen strategy, considering they make it possible to transport and distribute the gas with ease. Even the EU is starting to take note, having published a “hydrogen strategy for a climate-neutral Europe” in early July, explained Peter Pfeifer, group lead at KIT.

There are good arguments in favor of LOHCs. Not only can they be easily transported inside barrels and canisters but they also require a fueling infrastructure very similar to that of gasoline so they can be sold at gas stations as well. Moreover, taking the fuel system into account, LOHCs have greater volumetric and gravimetric densities than conventional options. The weight of ultra-cold or high-pressure hydrogen and its storage equipment is considerably higher than that of an LOHC stored in a plastic canister.

The above explains why the researchers at KIT are putting so much effort into finding new solutions. And they have help from a whole host of partner organizations, including FAU Erlangen-Nürnberg university, Areva H2Gen, Clariant Produkte, Forschungszentrum Jülich, Framatome, Fraunhofer ISE, Hydrogenious Technologies, Schott and Aachen’s RWTH university.

“Thanks to the P2X project, we have already been able to demonstrate that delivering hydrogen stored in LOHCs is more economical than using other methods, even if you transport as little as 60 tons a day to remote locations,” said Pfeifer. The findings will be especially helpful to fueling station operators and industrial users, such as glass manufacturers. The latter could use the energy stored in the gas for melting components. “LOHCs are therefore an excellent solution for transitioning from an oil to a hydrogen economy,” he added.

Author: Niels Hendrik Petersen