Propane vs Natural Gas

Would someone please fill me in on why we use propane and not natural gas? I read the Wikipedia article at

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and I still don't understand the difference. I do know that propane appliances such as ranges require adjustment to or different burners for each. Why not eliminate this problem and just use LNG only? In terms of household heating the only difference then would be that in one case you have a pipe coming in from the utility and in the other you have a big tank in the back/front yard and a tanker comes and fills you up from time to time. Or for your barbeque you go to the home center and instead of propane you get a tank or a refill of LNG.

Reply to
YouDontNeedToKnow
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Natural gas is mostly methane. It's attractive as a fuel because it's plentiful, but it's also very difficult to turn into a liquid. Any fuel that you transport in tanks wants to be a liquid because you can store many times as much fuel in a given volume tank as a liquid than as a compressed gas.

Let's back up a bit: Butane is easy to handle because the amount of pressure needed to keep it liquid at room temperature can be provided by a plastic container (e.g. cheap butane lighter) or a very thin aluminum can. Thus, you can carry a lot of fuel in a small, light tank. But it's relatively expensive.

Propane requires considerably higher pressure to be liquid at room temperature, so it has to be stored in heavier steel tanks that can withstand the pressure. But it *is* liquid in there, so again you can have quite a bit of fuel inside one small tank.

Methane cannot be practically compressed into a liquid at room temperature. You can make it liquid by making it very cold; that's how LNG (liquid natural gas) is produced. But it's got to stay cold to stay liquid, just like liquid oxygen or nitrogen. It's practical to ship very large volumes of it in specially-insulated tanks in ships, but it's not practical to keep that cold in a tank on your car or barbecue.

So when you see a car or bus powered by compressed natural gas (CNG), it tends to have very large tanks to hold a relatively small amount of gas, since there is no liquid in the tanks. Propane will power a car for much longer with a smaller tank. So CNG isn't very popular as a vehicle fuel.

It isn't practical for house heating or stove or barbecue either. If a trunk brought you liquid natural gas, you'd need cryogenic storage (which is expensive) and you would continually lose some fuel to boil off. If a truck brought you compressed natural gas, you'd need large tanks, and you'd have to wait for a compressor to re-pressurize them during fillup.

Natural gas *is* practical if it can be brought to you in gas form at normal temperature by pipeline. It's just not practical to store or distribute in a tank except on an enormous scale.

Dave

Reply to
Dave Martindale

Dave,

Great Post.

Dave

Reply to
Zephyr

Perhaps where you live, everyone has the ability to hook up to a natural gas utility. There are large areas of the country where that's not the case.

Jo Ann

Reply to
hillacc at yahoo.com

It's my understanding that propane is more expensive. But I don't know if the people why say that considered all the hookup fees, distribution fees, and other nusiance charges with any utility hookup.

Reply to
scott21230

I don't know of anyone (in their right mind) using propane where natural is available. Propane is a last resort where natural gas is not available.

Reply to
Steve Barker

If natural gas were to become available in my area, I would kicking, pushing and punching my way to the front of the line. I pay $90.00 a year to rent my 450-litre tank and with each fill-up, I'm charged a $6.00 delivery fee and an additional $4.00 hazardous material handling fee. The cost per litre, as of my last delivery, was $1.05 and if my math is correct, that works out to be $4.00 per U.S. gallon (then add tax). If I had access to natural gas, my total, overall cost would be roughly one-third that.

OK, I now need to spit.

Cheers, Paul

Reply to
Paul M. Eldridge

True, but re-read the post. Aside from Dave, everyone is missing the OP's one question. Why not deliver LNG instead of propane? LNG is being used is some applications, like cars, but it is not as universal as propane, now will it ever be as pointed out in a detailed and interesting post by Dave Martindale.

Reply to
Edwin Pawlowski

Hi Edwin,

I'm not absolutely sure about this, but I thought you had to cool natural gas to minus 160 Celsius in order to transport it as a liquid, then obviously reheat it again to revert it back to its original gaseous state. The dollar and energy cost to do this in terms of local delivery and long-term on-site storage I expect would be enormous.

Cheers, Paul

Reply to
Paul M. Eldridge

Hi Edwin,

Were you thinking of "compressed" natural gas or CNG, as opposed to "liquid" natural gas (LNG)?

CNG requires a much larger volume of storage and very high pressures

-- I believe something in the range of 3000 to 4000 pounds per sq. inch. It might work OK for vehicles where on-board storage requirements are relatively modest, but for higher volume residential applications, it isn't likely to work all that well.

Cheers, Paul

Reply to
Paul M. Eldridge

Yes, CNG is the one generally use., but according to this, both can be used.

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Seems like CNG is the cost effective method.

Reply to
Edwin Pawlowski

Hi Edwin,

Thanks for the links. Assuming CNG is the way to go (because I'm still not sure how long we can cost-effectively store LNG at those very low temperatures), do you have a sense of the size tank required to supply an average home?

For argument's sake, we might assume a "typical" residence uses about

100 therms of natural gas per month during the winter season (e.g., space heating, domestic hot water, cooking, dryer), and that deliveries are scheduled about once a month (it might be closer to every three weeks but throwing in an extra week as a margin of safety in the event of weather delays, etc.).

As a point of reference, I believe one U.S. gallon of propane contains a little over 91,000 BTUs, so 100 therms is roughly equal to 110 gallons or just about an entire 120 gallon/450 litre tank. I'm guessing a 120 gallon tank is about two-and-a-half in diameter and maybe five or so feet high.

I'm not exactly sure how they compare in terms of volumetric energy density, but my hunch is that CNG would come in much lower than liquid propane; perhaps as little as 1/10th? (That's purely a guess; I really don't know).

In any event, I'm thinking the high cost and large size of the on-site storage tanks (as well as those of the delivery trucks) would make CNG a very expensive alternative to propane. Plus, at 3,000 or 4,000 PSI, I'm not sure I'd want to be standing next to one if it should suddenly spring a leak!

Cheers, Paul

Reply to
Paul M. Eldridge

As opposed to propane....

more expensive, more dangerous, it lays on floor if it leaks, requires better plumbing, delivery fees, no unlimited supply, tank in yard.

propane has lots of downsides

Reply to
hallerb

Yeah, i noticed that after i posted. Thanks for the heads up.

Reply to
Steve Barker

I would imagine that a large portion of the cost of propane is in the costs of storing and transporting it, rather than the actual cost of the fuel as it is produced. Figure these expenses in along with the much more expensive storage tanks of CNG, and CNG delivered would probably be even more expensive than propane. Larry

Reply to
lp13-30

Reply to
YouDontNeedToKnow

nat gas is there,without having to call a truck to bring it. and having had propane in my early days,it was way more expensive than nat gas.... it cracks me up when i see the commercials about how great and cheap propane and heating oil is...lucas

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Reply to
ds549

The retail price of propane, as is the case with any other commodity, is determined entirely by supply and demand. The costs of production, transportation, storage, etc. are borne by those who touch it before you get it home.

Reply to
Mike Hartigan

Everything is relative. If I want natural gas, it will be about $20,000 to run the line to my house. After that it gets a bit cheaper than oil.

Reply to
Edwin Pawlowski

There are several downfalls to Propane

  1. The BTU content for Propane is lower than NG and Oil
  2. It is dangerous
  3. Requires refills by propane truck (similar to oil delivery)

Except for a swimming pool heater you will never see propane used where Nat is available (i could not back up never)

Ed, believe it or not Oil was cheaper to heat with this year than NG. I don't think you can compae the two in price. One year ones higher and the next year the other is. I think it is genuinely a wash in the long run

Reply to
Bob Pietrangelo

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