Assuming H2 powered vehicles (either burning H2 directly or feeding into fuel cells) catch on and reach a critical adoption threshold, they will need refueling with pressurized H2 gas. This will need H2 filling stations, H2 transport to those stations and a whole new infrastructure including storage and pipelines. The ability to have a pressurized H2 tank and pump near any fire hydrant eliminates having to install this distribution network.
The water pipelines for the city water distribution system are pressurized with H2 at the point (or close to the point) of manufacture during the early morning hours (say 2 AM to 6 AM). This dissolved H2 under pressure finds its way to fire hydrants. A pressure regulated valve opens and causes the gas to escape into the H2 tank installed beside the fire hydrant. A compression pump comresses the H2 in the tank. At 6 AM, the pressure in the H2 pump is (say) 100 atm, at which point, the source H2 is removed from the water distribution pipelines and the city water distribution system carries water only as usual. The vehicles are filled with the compressed H2 in the pressure tank using conventional pump handles and quick-connects.
Advantages: No need to build extensive H2 distribution and filling systems within city limits since fire hydrants are already installed. A pressure tank will need to be installed near some fire hydrants to collect and dispense the H2.
Disadvantages: Still need H2 trucks to connect to water pipelines in each city. Will need to build H2 pressure tanks and pumps near selected fire hydrants. H2 will be wet so will need dessicants in the pressure tank. Cannot have vent pipes from H2 intake into water pipelines till fire hydrant.
Shireesh Apte Jul 07, 2022