On Mon, 17 Aug 2009 12:22:00 +0100, David Cantrell
wrote:

Yes, that would require lots of infrastructure, which would take time to
roll out (just look at how slowly LPG is spreading),


LPG is spreading slowly only because the government doesn't want to
encourage more consumption of LPG than is available from the
"associated gas" that would otherwise have been flared off. The whole
point of LPG in road vehicles is to use productively a gas that would
otherwise be flared and go straight to CO2.

Any LPG consumption over and above that quanitity has to be sourced
elsewhere, and is thus not "low CO2". So there is a balancing act
needed; when the government actively wanted people to use this LPG in
road vehicles it offered subsidies to convert petrol-powered vehicles
to run on it; now that supply and demand are broadly balanced, those
subsidies have been withdrawn.

There won't be any future expansion in LPG use because the supply is
now dwindling. That's why availability of LPG is not spreading.