Good question.
First question is, where does the hydrogen come from? Most of it is reformed from natural gas, which still needs a fossil fuel as a base. Until we have a huge surplus of renewables or nuclear, I don't think it makes sense to use electrolysis to get it from water.
Second, it takes another big amount of energy to compress it, chill/liquefy it, then transport it. To the point where one chart I saw put EVs at getting 3x more "work" out of the same electricity input than a similar car would get from hydrogen. For comparison, an EV can go ~30 miles on the energy it takes to create a gallon of gas from the feedstock, so there's that too.
Then, it needs to be stored and transferred under high pressure. We've all seen the dumb things people do putting gas in their cars, and that's easy. Imagine everyone trying to fill their own propane tank
Yep. Pretty much nailed it. I work for a major industrial gas/air separation company. I managed a couple of different projects around H2 for transportation. Southern California has the most dense infrastructure for H2 dispensing. Coincidnetly, we have a large H2 production facility near Ontario CA, so delivery costs is pretty low to these refueling stations which is a plus.
It is true a majority of H2 comes from Steam Methane reforming. There are some newer technologies currently being deployed (I was just at a new facility two weeks ago that is getting ready to start up) that is much more efficient and doesn't produce as much CO2 as by product. Other methods of H2 generation is from tail gas from other chemical processes. We are also looking at installing some green energy H2 generation at one of our plants that gets power from a renewable resource. For transportation use, its delivered to the refueling stations as either liquid, and vaporized and pressurized at the station, or delivered as high pressure gas and small compressors refill cylinders in a cascading fill system. Some of the limiting factors was how to store enough H2 to make a vehicle practical. High pressure storage on board has been limited by the DOT approval of storage tanks. The new technology is storage tanks that have a steel thin wall liner with carbon fiber wound out casing. The manufacturers of these tubes have been pushing the limits and we are seeing 520 bar (7500 psi) and soon 620 bar tubes. The costs of H2, as measured per energy used per mile is comparable to gasoline but in everything we deal with, it isn't combusted, but used in on board fuel cells to generate power for electric motors.
There, as mentioned, the refueling issue. I performed a product safety analysis on refueling stations many years ago. Statistically speaking, incidences were comparable to regular gasoline fuel pumps. But, the technology at the time wasn't widely distributed. There was an indecent at one of our customers where there was a failure of an interlock that let H2 leak. H2 will ignite almost instantly.
