>>14242289>all synthesis of fuel has low efficiency. you put in a lot of energy and get back considerably less energy.>it's possible to synthesize simple hydrocarbons and make fuel that runs on regular enginesThe problem with HC synthesis is that it is messy or wasteful or both. And any gain you get, ends up being wasted in the heat cycle or powertrain friction, in any of these stupid reciprocating, nearly 19th century internal combustion engines, dressed up by designers to look cool. In reality, all they are is old farm equipment with a designer shell.
You don't have to synthesize H2, it is a thermodynamic degradation byproduct. With catalysis, it can be quite efficient in conversion. Industrial production, with solar power being the surplus energy input, the production of H2 at massive scale should be relatively efficient. I see it being most useful as part of a system that stores surplus energy, while being able to produce both stored energy as electricity, and purified water.
>>142422933000 psi is the tank rating. It is a lot, but, nothing special. The pressure in the tank also means that you do not need "more bulk on the container" as the gas needs only a small device to control the rate of expansion from liquid to gas, and regulator for mixtures with air- much simpler than all the equipment necessary for liquid fossil fuels delivery and mixing and operating.
Leakage is not a major problem. Tanks designed for gas confinement might leak a tiny bit- and have pressure and safety features built into valve bodies- but no system is perfect. At any rate, controlled release of the gas into a system might leak a little bit, but those leaks aren't likely to build up enough fuel in air to be explosive. It all depends on the design of the system if using certified components and best practices.
Most accidents involving hydrogen don't involve pressurized H2:
>https://www.osha.gov/pls/imis/AccidentSearch.search?acc_keyword=%22Hydrogen%22&keyword_list=on 
