Photo: Fraunhofer IFAM

For small vehicles: German researchers develop a paste as a hydrogen storage tank

Hydrogen is seen as the driving force of the future. While the first hydrogen cars are already driving over German roads, the usual pressure tank for e-scooters is not manageable. The POWERPASTE provides an alternative: Hydrogen can be safely stored chemically, easily transported and refuelled without expensive filling station infrastructure. A team of researchers at the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM in Dresden has developed the paste, which is based on magnesium hydride.

Gasoline and diesel engines powered by fossil fuels are becoming phase-out models due to climate change – instead, new propulsion options are being launched. One of the fuel hopefuls is hydrogen. It is usually pressed into the pressure tanks of the vehicles at 700 times the atmospheric pressure. From there, it flows into a fuel cell, where it is converted into electricity. The current, in turn, feeds an electric motor that drives the vehicle. For cars, this approach is already quite mature: several hundred hydrogen cars are already driving on Germany’s roads. And the German hydrogen filling station network is to be expanded from the current 100 to 400 filling stations over the next three years. However, small vehicles such as e-scooters, scooters and the like do not use this very much: the pressure shock during refuelling would be too great. So is this the “off” of hydrogen technology for e-scooters and co.?

POWERPASTE: The hydrogen response for small vehicles

Absolutely not! Researchers at the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research IFAM in Dresden have developed a hydrogen solution that is perfect for small vehicles: the POWERPASTE, which is based on the solid magnesium hydride. “With POWERPASTE, hydrogen can be chemically stored at room temperature and ambient pressure and released as needed,” says Dr. Marcus Vogt, a scientist at Fraunhofer IFAM. This is uncritical even if the scooter is in the sun for hours in the summer heat, because the POWERPASTE only decomposes above about 250 degrees Celsius. The refuelling process is very simple: instead of heading to a gas station, the scooter driver simply changes a cartridge and additionally fills tap water into a water tank – ready. He can also do this comfortably at home or on the go.

The starting material of the POWERPASTE is powdered magnesium – one of the most common elements and thus an readily available raw material. At 350 degrees Celsius and five to six times the atmospheric pressure, this is converted into magnesium hydride with hydrogen. Now esters and metal salt are added – and the POWERPASTE is ready. To drive the vehicle, a stamp transports the POWERPASTE out of the cartridge. Water is added from the water tank, resulting in gaseous hydrogen. The quantity is adjusted highly dynamically to the hydrogen demand of the fuel cell. The highlight: Only half of the hydrogen comes from the POWERPASTE, the other half supplies the water. »The energy storage density of the POWERPASTE is therefore enormous: it is significantly higher than with a 700 bar pressure tank. Compared to batteries, it even has ten times the energy storage density,” says Vogt. For the driver, this means that the POWERPASTE achieves a similar range to the same amount of gasoline, if not a larger one. The POWERPASTE also performs better when comparing ranges with hydrogen compressed to 700 bar.

Only suitable for e-scooters? Because of…

This also makes the POWERPASTE interesting for cars, delivery vehicles or range extenders – which increase the range of electric cars. Yes, even large drones could significantly increase their range with the hydrogen paste, leaving them in the air for several hours instead of twenty minutes. This is particularly helpful for inspection tasks, such as the inspection of forest areas or power lines. A slightly different kind of application is offered when camping: Here, the POWERPASTE can provide electricity for coffee maker and toaster via fuel cell.

Lack of infrastructure? Here, too, the POWERPASTE scores.

In addition to the long range, there is another point that speaks for the POWERPASTE: While gaseous hydrogen requires a cost-intensive infrastructure, the POWERPASTE can also be used where such an infrastructure is lacking. In other words, where there are no hydrogen filling stations. Instead, any gas station could offer POWERPASTE in cartridges or canisters. This is because the paste is flowable and pumpable – it can therefore also be refuelled via a normal refuelling process and comparatively cost-effective filling lines. Petrol stations could initially offer the POWERPASTE in smaller quantities, for example from a metal barrel, and expand the supply according to demand – with investment costs of several tens of thousands of euros. By way of comparison, filling stations for gaseous hydrogen at high pressure are currently costing around one to two million euros per pump. The transport of the paste is also cost-effective: after all, complex pressure tanks or very cold liquid hydrogen are not necessary.

Pilot centre planned for 2021
At the Fraunhofer Project Center for Energy Storage and Systems ZESS, Fraunhofer IFAM is currently setting up a production plant for POWERPASTE. It is scheduled to go into operation at the end of 2021 and then produce up to four tons of POWERPASTE per year. Not just for e-scooters, of course.