I helped wire up some natural gas filling pumps back in 1998 for the City of Long Beach CA. And it was not the first filling station.
The huge advantage is the cost is currently running only about $2 - $2.50 per gallon. The huge disadvantage is the high pressure tank is somewhere between 3,200 and 4,000 PSI working pressure, and needs to be test pressure at 25% higher without leaking. So the tanks will cost a lot to build. And need to be removed from the vehicle to dunk in a water tank while testing them every few years.
So I don't see the conversion price going really low. And one of the reasons there is a high price to the natural gas is the cost to run the compressors. At the City of Long Beach, our largest refueling site was converted to run natural gas compressors to make the 4,500 PSI fuel. This was used to refill many city owned vehicles and several dozen taxi cabs. Private cars could also refill there, however I never saw one private car fill there from 1998 to 2004 when I left the City.
We had a couple dozen Honda cars, with a tank in the truck, that would drive about 90 miles between refills. So if you where going to a conference outside the city, they might give you a pool car, and you would have to refill it just before leaving, fill it when you got back because it was under 1/4 tank.
The Honda was rated to only give off 2 grams of CO in 100,000 miles. Much less than my 75 pickup would give off on one cold start.
LNG will probably be the best fuel in the future to power things like municipal bus or larger delivery trucks. LNG is natural gas chilled to -150F then it becomes much more dense. So a 60 gallon tank can run all day on a large garbage collection truck, or municipal 60 passenger bus. The tanks are super insulated, but only have to maintain about 10 PSI in them.
Gas is boiled off to maintain the super cold temperatures, and if required, then the liquid is heated and boiled to run to the engine. The engines are normal diesel engines, some running on pure gas, some running on a 85% mixture of natural gas, the rest a small amount of diesel fuel added to both lubricate the piston and save some fuel costs.
Of course there are a few drawbacks, like if you park the vehicle for a week, the superinsulated tank will get warm, the pressure go over 10 PSI, and start to vent large volumes of natural gas to the area. And chilling the natural gas to -150F takes a lot of energy. So it becomes economical if you can get the LNG straight from a shipping container, but there is a lot of "NIMBY" going on with placing a shipping terminal in someone's back yard. Long Beach certainly does not want a natural gas terminal - at least a few vocal residents are preventing it from coming there, even though it will mean lower cost natural gas, and ability to make CNG without compressing it. If you leave LNG in a high pressure tank, it will become CNG as the LNG warms up.
They where considering a LNG port near Oceanside, and perhaps on the Marine Training Station near there. But it seems like no Pacific coast ports want a CNG loading terminal.
Fred.
