Thanks, tok-tokkie, nice graph, it makes everything clearer. BTW, energy density of hydrogen it's more or less the density of natural gas.
It's true that the tank is larger, but not much when compared with a regular gasoline tank.Tank for NGV, with similar energy density of hydrogen (this is a large tank, duplex, btw)
NGV (Natural Gas for Vehicles) shows clearly that there is no significant problems in switching from one source of fuel to another, even if it has less energy density.
Colombia has moved from 6,000 vehicles using NGV to 290.000 in seven years (since 2000 until 2007). Right now Brazil (with 1.9 million vehicles) and Argentina (with 1.5 million) has an NGV fleet larger than the colombian one.
In only seven years Colombia has moved up to eight place in the world in terms of NGV use, no big deal: the main factor is the price of NGV, it's cheaper than gasoline (60% or 70% of the cost after taking in account the different energy density).
The cost of a conversion kit goes around 1.500 to 2.000 U$, so only new cars take the "price hit", it's not practical to convert a car with less than 5 years of use, because of the time it takes to repay the conversion by the fuel money savings.
This is not the case of public transportation vehicles (taxis and buses) because they have a yearly mileage that can be four or five times the one of a regular car, so they repay the investment in a year or so. In the end, most taxis and buses have moved to NGV.
A network of 500 gas stations was created in those seven years.
Natural Gas is the most used fuel source in the world after oil, it has around 24% of the world market of energy. It contaminates less than oil, btw.
After watching the growth of infrastructure, once the government had a policy in place, I don't see why hydrogen couldn't follow the same trend, except, as I mentioned, because of the contamination and price issues that makes hydrogen a poor choice nowadays
About the cooling issues, the system in place moves the gas through pipes and delivered in gas form into the stations. There is a compressor at the gas station (moved by gas, of course) that liquefies the NGV while it is being served to the client.