Interesting new development, with hydrogen fuel cells and the supposedly safer storage of the H2 gas. 'Bath sponge' breakthrough could boost cleaner cars @ BBC, 4/18/20. After reading this, I seem to recall that the Hindenberg (Zeppelin) was full of hydrogen and had an aluminum- and iron oxide-based paint on the skin that turned out to be highly reactive. Certain rocket fuels also apparently have powdered aluminum in the fuel mix (when mixed with an oxidizer it can be highly reactive). And, wasn't it Apollo 1 where high pressures and the aluminum present in the capsule raised the risk of fire breaking out? Nice advance in the tech, assuming they've worked through all the little problems of incorrectly bringing aluminum and hydrogen together. Imagine ... more-cheaply and safely storing H2 onboard moving vehicles. Now, if they can just crack the problem of producing enough of the stuff to matter.