German researchers find a solution to the hydrogen storage problem: salts.
Researchers at the Leibniz Institute of Catalysis have found a relatively simple solution to the giant problem of storage and transport of hydrogen as fuel. In a paper published today in the American Chemical Society Central Science, the researchers share a method of storing hydrogen in solid salts.
In a world that is looking for a pollution-free generation of energy on demand, hydrogen fits the bill perfectly. The fuel can be burned in a controlled manner using oxygen from the air and produces water as a by-product. The generation of the fuel itself can also be emission-free if renewable energies are used.
At Interesting Engineering, we have previously reported how fuel could solve the problems of long-haul transport as the aviation sector looks to go electric. However, it is the storage and transportation of the fuel that presents a huge challenge in this endeavor.
How to store hydrogen fuel?
Hydrogen is a highly flammable gas and dealing with large quantities is quite cumbersome. As a fuel, it also needs to be transported to fueling stations that will be set up in the future. So, researchers have attempted to liquify it as we do with natural gas.
Conversion of hydrogen gas into its liquid state requires ultra-low temperatures of negative 423 Fahrenheit (-253oC), according to the U.S. Department of Energy's website. Additionally, it also requires the use of vessels that can handle high pressure, all of which add to the cost of using the fuel, making it more expensive and unviable for the market.
The other option is to store hydrogen in solid salts. The greatest advantage of this method is that the process is reversible meaning the salts can be reused again to store more hydrogen, making it a cyclic process. The disadvantage of the method, though, is that it uses precious metals as catalysts, and the process results in the production of carbon dioxide.
German researchers solve the problem
Researchers at the Leibniz Institute of Catalysis looked into the problem and developed an energy storage and release system using carbonate and bicarbonate salts, while also using metal manganese, which is more widely available.
The researchers found that by converting bicarbonate and hydrogen into formate - the salt of formic acid was most effective with potassium in the presence of manganese as a catalyst.
Interestingly, lysine, an amino acid, a component of proteins in biological systems, also acted as a promoter of the reaction and worked to capture carbon dioxide and prevent it from releasing. The reaction temperature for the process remains below 200 Fahrenheit (93oC), which is less hot than a boiling pot of water.
Results of their research showed that after five cycles, the method gave a high yield of hydrogen at 80 percent. More importantly, the hydrogen released was 99 percent pure, paving the way for its use in commercial applications. When glutamic acid was used in the process, the yield of the hydrogen increased to 94 percent.
The research was published in the journal ACS Central Science.
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