Technology

A part of the network is difficult to electrify and it cost a lot. So H2 still a good alternative.exoerinentation since 2016 show that it is successful. In France there is 1415 km electrified, the small network is representing 15 000 km. You ser the point ?

Storage and transport of H2 is a big deal because of the unique properties (very low transition temp/very high pressure for liquid). That generally means for a non-pressurized, non-cryogenic storage it has to be combined into another molecule and then catalyzed back out, real time, for use. And, of course, the ignition ratio range (4%-75% in air) means that it's very easy to accidentally ignite a H2 leak; substantially easier than most other fuels, though this is mitigated by it's density and ability to disperse in an unenclosed area.

Production is theoretically energy efficient as you can create it with hydrolysis, but the cheapest way of producing it, by far, is cracking of methane, which requires a high temperature process to create. It may not produce a high volume of CO2, but it perpetuates the cycle of exploration and extraction of gaseous hydrocarbons and the related environmental dangers and downsides.

No it's not stored as liquid BLEVE is not a concern here, but there is plenty of issues with explosivity and very high preasures which can be 300-500 bar (~atm) depending on the application.