We’ve been promised hydrogen-powered engines for some time now. One downside though is the need for hydrogen vehicles to have heavy high-pressure tanks. While a 700 bar tank and the accompanying fuel cell is acceptable for a city bus or a truck, it becomes problematic with smaller vehicles, especially ones such as scooters or even full-sized motorcycles. The Fraunhofer Institute wants to run smaller vehicles on magnesium hydride in a paste form that they call POWERPASTE.
The idea is that the paste effectively stores hydrogen at normal temperature and pressure, where it stays chemically locked until mixed with water. The researchers note that it will decompose around 250 °C, but while your motorcycle may seem hot when parked in the sun, it isn’t getting quite to 250C.
Interestingly, the paste only provides half the available hydrogen. The rest is from water added start a reaction to release the hydrogen. Fraunhofer claims the energy density available is greater than that of a 700 bar tank in a conventional hydrogen system and ten times more than current battery technology.
One thing that’s attractive is that the paste is easy to store and pump. A gas station, for example, could invest $20-30,000 and dispense the paste from a metal drum to meet low demand and then scale up as needed. A hydrogen pumping setup starts at about $1.2 million. Fraunhofer is building a pilot production plant that will produce about four tons of the material a year.
This isn’t a totally new idea, of course. Using metal hydrides to store hydrogen chemically has other proponents, including French company McPhy energy. There have also been schemes to use other hydrides in powder form as well as chemical hydrogen carriers like formic acid and ammonia.