Shelf Life for Natural Gas

A few tens of millions of years.

It was being stored when we dug it up - no?

And be wary of casual names - there are several different things sold or called "town gas". And used in roughly the same way - although the actual characteristics are not similar at all.

And 'town gas" was never a name for natural gas, it was the process of the gassifying of other products such as coal, so also called coal gas.

And dry gas and sale gas describe "states" of a product, not the source.

But even within this definition "it is used in Europe and North America for heating and cooking" you have only narrowed the question to maybe six different products. Some delivered by pipe, some in bottles, some liquids in cans that are gassified before burning.

"and is piped to customers over many hundreds of miles" Now this part gets it pretty well narrowed down in North America - but I do not know if the same is true in Europe.

But it is common to see people refer to the "natural gas" delivered to the tank out back in the western US. That is NOT natural gas, it is compressed and liquified propane. Won't run the same equipment.

Hi folks, thanks for the information. Yes, they do have the "Big Inch" in Europe and the former Soviet Union for gas delivery. This is one of the ways that Russia is able to flex their economic muscle in lieu of tanks and bombers. They simply control a big percentage of the gas flow to Western and Central Europe and have the ability to cut it off whenever they want to do so.

I suppose you could put what we in the US call natural gas in the tank out back of the house but you get more BTU's with the Propane than you will out of the NG.

Natural gas (at least in the US) is nearly all methane, with 5% or so other gases. Methane can not be liquified by reasonable pressures and temperatures, like propane can, so a tank in your back yard can't hold much.

There is roughly a 2000:1 reduction in volume when a gas is converted to a liquid, so if your propane tank can keep you going for 200 days (which is just about right for mine), filling that same tank with natural gas would keep you going for 1/10 of a day, or about 2.4 hours. And that is without paying attention to the pressure changing as you use up the gas... Liquid propane boils when the pressure starts to drop, keeping the pressure in the tank quite constant until all the liquid is gone.

As PW indicated, either natural gas or propane should last indefinitely. An automotive "gas" tank (for storing gasoline) is open to the atmosphere, so expansion and contraction lead to water condensing in the tank. In humid climates that can become a real problem. Since propane is stored under pressure in a sealed tank, there is no way for water to get in (except by delivery from a badly maintained plant or truck).

Hello Vagabond

You wrote you get more BTU's with the Propane than you will out of the NG. That's true on basis of volume of gas, because propane has higher density than NG (methane) as its molecular weight is higher. But on a mass basis hydrocarbons have pretty similar calorific values. Methane is a touch higher as the proportion of hydrogen to carbon is higher, then it levels off.

Cheers............Codey