Molecule profile: Dimethyl ether
Chemical hydrogen storage – what is that actually supposed to be? The question is of course completely justified, because the subject of hydrogen is highly complex, although H2 is the first and, in terms of its molecular structure, one of the simplest elements of all.
Roughly speaking, there are two methods of storing hydrogen: physical and chemical. Physical means that hydrogen is either compressed under high pressure or cooled to -253 degrees Celsius. In both cases, the volume is reduced. Chemical means that hydrogen reacts with another element to form a so-called hydrogen derivative. The reaction of hydrogen and carbon dioxide, for example, produces the derivative methane. Such derivatives are the focus of basic research at the Institute for Sustainable Hydrogen Economy (INW) at Forschungszentrum Jülich, which forms the core of our cluster.
The aim of all physical and chemical storage methods is to improve the manageability of hydrogen, for example to make it easier to transport. Each method is used to compress molecular hydrogen, which in its pure form under ambient conditions has a large volume that is more difficult to handle. Each method has its strengths, which are to be exploited for different applications. Hydrogen physically stored under pressure is used in mobility, for example, because trucks and buses are refueled with hydrogen compressed to 350 bar and cars with 700 bar.
As already mentioned, the INW concentrates on chemical storage methods, partly because the energy required for storage is usually lower than with physical methods. However, chemical storage methods also have their challenges. In this series, we present profiles of the chemical storage systems that our researchers are working on. We start with dimethyl ether, or DME for short, which many people know as the carrier in spray deodorants. It is liquid in the bottle under low pressure. When the spray head is pressed, DME escapes as a gas and transports the fragrance to the desired location.
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