Researchers at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden have developed a paste for hydrogen storage. The institute is calling the mass “power paste”.
The researchers also claim their paste to offer high energy densities and be suitable for all vehicles from electric scooters to cars. According to Fraunhofer IFAM, the power paste, based on the solid magnesium hydride, should allow hydrogen to be chemically stored at room temperature and ambient pressure and rereleased as required. Since the power paste only decomposes above about 250 degrees Celsius, this works without any issues even if, for example, a scooter equipped with the paste is left in the summer sun for hours.
The storage paste’s starting material is only magnesium in powder form, which is a very common element. At 350 degrees Celsius and five to six times atmospheric pressure, this is reacted with hydrogen to form magnesium hydride. The power paste is then produced with ester and metal salt.
The power paste replaces the cylindrical pressure tank used in fuel cell cars and buses. Therefore, the institute says that this solution is suitable for hydrogen drives in smaller vehicles in cases where a pressure tank would be difficult to implement.
According to the Fraunhofer researchers, the refuelling process is straightforward. Instead of driving to a filling station, the scooter driver changes a cartridge and fills tap water into a water tank. In the vehicle itself, the paste is pressed out of the cartridge and mixed with a precisely measured amount of water, depending on the required power. This reaction produces gaseous hydrogen, which can then be converted into electricity for the electric motor.
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Only half of the hydrogen comes from the power paste, the other half from the water in the reaction. “The energy storage density of the power paste is therefore enormous: it is much higher than that of a 700 bar pressure tank,” says Marcus Vogt, a scientist at Fraunhofer IFAM. “Compared to batteries, it even has ten times the energy storage density.” The Fraunhofer scientists even say that the driver should achieve a similar range with the power paste extrapolated to a car as they would with the same amount of petrol, if not greater.
This kind of material’s advantages are fairly clear: a cartridge of the paste could theoretically be swapped out anywhere along a journey. Similarly, the researchers say the paste could significantly extend the flight time of large drones, thereby allowing them to fly for several hours rather than just 20 minutes. For forestry workers, surveyors or high-voltage electricians, this would allow the inspection of forestry or power lines with a drone. In a domestic kind of application, campers might also use the paste in a fuel cell to generate electricity to power a coffeemaker or toaster.
The researchers see another major advantage of their development: the paste can flow and be pumped, so aside from cartridges and canisters, the paste can also be “filled up” at a filling station. The expensive infrastructure for gaseous hydrogen at high pressure or cryogenic liquid hydrogen at – 253 degrees Celsius would no longer be necessary.
In terms of the paste’s viability, which encompasses environmental and energy balance and production and scalability, Fraunhofer IFAM is currently building a production facility at the Fraunhofer Project Center for Energy Storage Systems ZESS. This should go into operation at the end of 2021 and then produce up to four tonnes of power paste per year.
Including reporting from Sebastian Schaal, Germany.
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