Fraunhofer suggests e-scooters as application for its magnesium hydride paste hydrogen storage technology
Researchers at Germany’s Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden have developed an ultra-high-capacity hydrogen storage substance for PEM fuel cell applications based on solid magnesium hydride. Fraunhofer’s POWERPASTE releases hydrogen on contact with water. It has a hydrogen capacity of about 10 mass-% (i.e. 10 kg POWERPASTE → 1 kg hydrogen). This is a specific energy of 1.6 kWh/kg and an energy density of 1.9 kWh/liter—about 10 times the capacity of Li-Ion batteries.
Specific energies and energy densities including conversion losses. Source: Fraunhofer IFAM
The award-winning POWERPASTE technology is patented (EU, US) and offers advantages over other energy storage technologies, in particular in the power range from 100 W to 10 kW, Fraunhofer researchers said.
Now, Fraunhofer is suggesting the use of POWERPASTE for use with e-scooters. Hydrogen is not currently an option for small vehicles such as electric scooters and motorcycles, since the pressure surge during refilling would be too great. POWERPASTE, on the other hand, the researchers suggest, would be ideal.
POWERPASTE (left); POWERPASTE cartridge (middle); portable 100 W power supply unit (right). Source: Fraunhofer IFAM
POWERPASTE stores hydrogen in a chemical form at room temperature and atmospheric pressure to be then released on demand, said Dr. Marcus Vogt, research associate at Fraunhofer IFAM. POWERPASTE only begins to decompose at temperatures of around 250 °C, so it remains safe even when an e-scooter stands in the sun for hours.
Refueling would be simple; riders merely have to replace an empty cartridge with a new one and then refill a tank with water. This can be done either at home or underway.
To create POWERPASTE, magnesium powder is combined with hydrogen to form magnesium hydride in a process conducted at 350 °C and five to six times atmospheric pressure. An ester and a metal salt are then added in order to form the finished product.
Onboard the vehicle, the POWERPASTE is released from a cartridge by means of a plunger. When water is added from an onboard tank, the ensuing reaction generates hydrogen gas in a quantity dynamically adjusted to the actual requirements of the fuel cell. Only half of the hydrogen originates from the POWERPASTE; the rest comes from the added water.
POWERPASTE thus has a huge energy storage density. It is substantially higher than that of a 700 bar high-pressure tank. And compared to batteries, it has ten times the energy storage density.—Marcus Vogt
This means that POWERPASTE can offers a range comparable to—or even greater than—gasoline. It also provides a higher range than compressed hydrogen at a pressure of 700 bar.
With its huge energy storage density, POWERPASTE is also an interesting option for cars, delivery vehicles and range extenders in battery-powered electric vehicles, Fraunhofer suggests. Similarly, it could also significantly extend the flight time of large drones, which would thereby be able to fly for several hours rather than a mere 20 minutes. This would be especially useful for survey work, such as the inspection of forestry or power lines. In another kind of application, campers might also use POWERPASTE in a fuel cell to generate electricity to power a coffeemaker or toaster.
Unlike gaseous hydrogen, POWERPASTE does not require a costly infrastructure. This makes it suited for areas lacking such an infrastructure. In places where there are no hydrogen stations, regular filling stations could sell POWERPASTE in cartridges or canisters instead. The paste is fluid and pumpable. It can therefore be supplied by a standard filling line, using relatively inexpensive equipment.
Initially, Fraunhofer suggests, filling stations could supply smaller quantities of POWERPASTE—from a metal drum, for example—and then expand in line with demand. This would require capital expenditure of several tens of thousands of euros. By way of comparison, a filling station to pump hydrogen at high pressure currently costs between one and two million euros for each fuel pump. POWERPASTE is also cheap to transport, since no costly high-pressure tanks are involved nor the use of extremely cold liquid hydrogen.
Fraunhofer IFAM is currently building a production plant for POWERPASTE at the Fraunhofer Project Center for Energy Storage and Systems ZESS. Scheduled to go into operation in 2021, this new facility will be able to produce up to four tons of POWERPASTE a year.