[norwaypinesavage]

For clarity, there seem to be three fuel sources discussed here that some are mixing together:
Compressed Natural Gas (CNG), the apparent fuel discussed most in the article. It requires 4000 psi storage tanks.
Liquefied Natural Gas (LNG). It must be stored in cryogenic containers at -260 degrees F.
Propane. It can be stored in fairly light weight tanks at below 300 psi. It is a by product of petroleum production and so has somewhat limited supply. It has roughly 2/3 the energy by weight and volume as gasoline.

All three systems require unique tanks, distribution systems, and carburetors, though nothing has to be invented to use them in production vehicles.

[thackney]

though nothing has to be invented to use them in production vehicles.

Natural Gas vehicles have been available straight from Honda for many years. Look up the Civic GX.

[PapaBear3625]

Liquefied Natural Gas (LNG). It must be stored in cryogenic containers at -260 degrees F.

And the LNG should get used up before it gets above cryogenic temperatures. That's why it's more suited for dual fuel tractor trailers. You fill up with both LNG and diesel, and run off LNG until your LNG tank is empty, then run off diesel until you get to another LNG fuel source.