Good point, I have to concede that one. I did not consider volume. However, The storage cylinders for compressed hydrogen are usually kept at about 70 Mpa (700 bars). I don’t kmnow if that is enough to make up for the density issue or not, but that is some serious compression. Also, the article said the tank contained supercompressed hydrogen. If 70 MPa is the norm, what is considered supercompressed? I couldn’t find an answer to that, do you know?
That only reduces the storage volume. Without that you would need to drive a blimp.
At that density in the storage tank, it can be close to the same energy density per unit volume of diesel, but you cannot have intake cycle of the engine operating at 10,000 psi or you will not be able to take in any air for combustion.