CNG vs LPG?

[Larryect Senior Member Find all posts View Profile Close Larryect]

I have a CNG Civic and I like it. But, I have wondered what the advantage is over LPG. LPG seems to be available in more areas. As far as I know it is much cleaner and currently cheaper than gasoline. It uses less pressure so the tanks are much cheaper. Are there disadvantages?

Thanks

[freedml Senior Member Find all posts View Profile Close freedml]

Re: CNG vs LPG?

I looked into LPG before deciding to go CNG. LPG is mostly available 8-5 Monday to Friday at rental yards, RV yards, and LPG specialty yards. There are two public pumps that I since located that are available 24/7 (Riverside and Person Fuels San Diego). So, availability is somewhat limited. LPG is still treated like an accessory fuel, not a transportation fuel.

In Utah generally or with a pump at home in California, you can buy your CNG from a regulated monopoly which supplies it at low, stable prices. I love it!

[afvman Guru / Moderator Find all posts View Profile Close afvman]

Re: CNG vs LPG?

Larry,

Hey, they're both better than gasoline!

From a technical standpoint LPG makes a lot of sense in a lot of applications, i.e., 85-90% of forklifts in the U.S. run on it. It has more energy density than CNG, is stored as a liquid but vaporizes at basically room temperature so it's delivered to the engine as a gas just like CNG.

It's not quite as 'clean' as NG because of the chemisty, but like I said...

So, lower pressures, greater energy density, much better infrastructure (at almost any UHaul) AND one less regulator.

LPG only needs a 'second' stage regulator before going to a mixer. Thus, the underhood equipment is virtually the same. Mixers are different but just slightly. Sounds like I'm biased but, I'm not.

Just the facts. They both have advantages and disadvantages.

Hope this helps,

afvman/Bill

[Larryect Senior Member Find all posts View Profile Close Larryect]

Re: CNG vs LPG?

It seems to me that many gas stations have LPG available. Not all but many more then CNG stations.

One trend I see that might concern me is the move to the tank exchange system and away from the bulk storage tanks. I have heard in the past of vehicles having reduced power and mileage. But, I suspect you have that on CNG conversions as well.

Would the cold weather operation be a larger problem than it is with CNG?

[freedml Senior Member Find all posts View Profile Close freedml]

Re: CNG vs LPG?

Some gas stations have LPG, but they often don't have anyone available or it takes a while for them to dispense it for you. U-Haul isn't open at night. Except for the two pumps I mentioned I don't know any other 'self-serve' LPG.

And LPG can be almost as expensive as gasoline -- you don't know until you ask them the price as they usually don't post it.

[Larryect Senior Member Find all posts View Profile Close Larryect]

Re: CNG vs LPG?

Some gas stations have LPG, but they often don't have anyone available or it takes a while for them to dispense it for you. U-Haul isn't open at night. Except for the two pumps I mentioned I don't know any other 'self-serve' LPG.

And LPG can be almost as expensive as gasoline -- you don't know until you ask them the price as they usually don't post it.

True.

Are there any EPA approved conversions for bi-fuel available? If LPG wasn't readily available you could run gasoline. But, I do remember times when there was no economic advantage of running LPG.

[Guest Close mwbare]

Re: CNG vs LPG?

LPG is mostly produced from the refining of crude oil. Seems as though the price would follow gasoline & wouldn't that contribute to more dependence on oil? LPG & propane here in Indianapolis was about $5 a gallon.

[Curtis Co-Founder CNGChat.com Find all posts View Profile Close Curtis]

Re: CNG vs LPG?

It seems to me that many gas stations have LPG available. Not all but many more then CNG stations.

One trend I see that might concern me is the move to the tank exchange system and away from the bulk storage tanks. I have heard in the past of vehicles having reduced power and mileage. But, I suspect you have that on CNG conversions as well.

Would the cold weather operation be a larger problem than it is with CNG?

Just because a place sells LPG doesn't mean they dispense for vehicles. They have to have a weights & measures dispenser, just like cng. Strangely enough, LPG for fuel runs about a dollar a gge less than tank LPG. The vehicles heater hoses gasify the liquid and can do so if only about room temperature. I don't know about very cold temps as to how it would effect a dedicated system. Bi-Fuel would be no problem, as you can warm up on gasoline, then switch. I did my ElCamino as bi-fuel since I only have two stations in my area that are basically 9a-5p weekdays.

[Curtis Co-Founder CNGChat.com Find all posts View Profile Close Curtis]

Re: CNG vs LPG?

As far as why dual fuel LPG, it was done prior to the current run-up in prices and I got the LPG tank and system for $125. LPG is currently $2.30 in my area as motor fuel, so it's actually cheaper right now than the cng at $2.65... go figure.

[Curtis Co-Founder CNGChat.com Find all posts View Profile Close Curtis]

Re: CNG vs LPG?

The real problem here is a lack of CARB approved, even EPA approved, kits. May not be so bad outside California, but here... better be a pre smog car.

[Dmitry Member Find all posts View Profile Close Dmitry]

Re: CNG vs LPG?

As far as why dual fuel LPG, it was done prior to the current run-up in prices and I got the LPG tank and system for $125. LPG is currently $2.30 in my area as motor fuel, so it's actually cheaper right now than the cng at $2.65... go figure.

Curt, I live in Monterey Bay area, CA. LPG at Suburban Propane, Marina is $3.60. CNG at PG&E, Salinas is $2.60, CNG at Monterey-Salinas Transit filling station is $1.12 for 3600 psi, but it's not available to the public. How do you get LPG "as motor fuel" - is there any legislative basis to this?

I personally believe the drive towards alternative fuels is strictly economic. So maybe propane IS a better option given the overall cost/benefit factor. Have you heard of any OEM LPG cars for sale in US? I know they have them in Japan and in Europe, but that's a sore subject. Thank you.

[dovh49 Member Find all posts View Profile Close dovh49]

Re: CNG vs LPG?

What would be nice is to take a dedicated CNG vehicle and then make it bi-fuel with LPG. Then you can go anywhere, be clean, and have a simpler more effecient set up than the normal bi-fuels with gasoline.

[jetboatjohnny Senior Member Find all posts View Profile Close jetboatjohnny]

Re: CNG vs LPG?

Propane went up to 2.49 (Hemet, CA 6/2/08)
Gasoline 4.21
Diesel 4.99......CNG still 2.194! YES

[Devo Member Find all posts View Profile Close Devo]

Re: CNG vs LPG?

There are some LPG trucks coming up at GSA Auctions - one is tomorrow.

[rkcarguy Member Find all posts View Profile Close rkcarguy]

Re: CNG vs LPG?

You are correct, CNG and LPG have almost identical fuel values. The problem is that CNG stays gaseous even at low temperatures. Propane is kept liquid by the combination of pressure and temperature. Aside from requiring a regulator to bring CNG down to a usable pressure(312PSI max like propane), I don't see why you couldn't use CNG on something already running LNG, but it won't work on the GX or anything electronically injecting the propane unless it's specially set-up for both.
Propane looses pressure the colder it gets, and below certain temps will not provide enough pressure to run the engine. The vaporizer may freeze up and not flow. There is a chart somewhere in the internet of the pressure/temperature relation for propane. CNG doesn't have any problems with that, but requires the crazy 3600 psi tanks and pump stations too.