Difference Between LPG & Natural Gas
LPG (propane) and Natural Gas (methane) are both used in essentially the same way but they are also different in many ways.
In Australia, we rely on both types of gas for our energy needs.
LPG and Natural Gas are widely available and used for thousands of applications in homes and business.
What are the Key Differences Between LPG vs Natural Gas?
• LPG (propane) and natural gas (methane) have different chemical formulas: Methane is CH4. Propane is C3H8.
• LPG has a higher calorific value - energy content - than natural gas, with 93.2MJ/m3 vs 38.7MJ/m3.
• For proper combustion, LPG requires an air to gas ratio of approximately 25:1 whilst natural gas requires a 10:1 ratio.
• LPG (propane) is more dense than air, at a relative density of 1.5219:1 vs natural gas (methane) at 0.5537:1, which is lighter than air.
• LPG can be compressed into a liquid and stored or transported in a cylinder or larger vessel.
• Natural gas and LPG appliances operate at different pressures.
• LPG can be easily processed into Simulated Natural Gas – SNG – and used as a substitute for natural gas. The same is not true in reverse.
Please read more for all of the details about the differences…
Methane and Propane Gas Properties (Natural Gas & LPG)
Energy Content: MJ/m3
Energy Content: Btu/ft3
Energy Content: MJ/kg
Boiling Temp: Cº
Flame Temp: Cº
Flame Temp: Fº
Gas Volume: m3/kg
Density @15ºC: kg/m3
The chemical formula for propane is C3H8.
The chemical formula for LPG can be the same, when it contains only propane.
However, it can also contain butane and isobutane.
The chemical formula for both butane and isobutane are the same - C4H10.
What is the Difference Between Methane and Natural Gas?
Processed natural gas, as delivered via gas mains, is typically almost pure methane.
So, there is really no difference between methane and natural gas.
However, unprocessed natural gas, straight from the gas well, contains NGLs and impurities in addition to methane.
LPG vs Natural Gas Price
Many people think that natural gas is cheaper than LPG but, in many cases, this is no longer true for two reasons:
1. Natural gas suppliers charge for something called a 'Daily Supply Charge' or by a similar name.
This is, in reality, a network access charge for being hooked up to the natural gas pipelines.
The problem is that the price of the Daily Supply Charge has been escalating and is now over $1 per day in many areas.
This amounts to over $400 per year, before you even get the first molecule of gas, with a number of natural gas tariffs.
2. The export of natural gas, in the form of LNG - Liquefied Natural Gas - has driven up the price of the gas itself.
The price is now driven by the world price for LNG, as buyers in other countries 'bid' for the same gas.
The end result is that LPG is now less expensive in many cases and especially for residential users with low to moderate rates of consumption.
Natural Gas Formula
The chemical formula for natural gas is CH4.
To be accurate, this is the chemical formula for methane, which is the primary constituent of refined natural gas.
Raw natural gas, straight out of the ground, also contains natural gas liquids and various impurities.
Calorific Value of LPG (Propane) vs Calorific Value of Natural Gas
Is Propane More Expensive than Natural Gas?
It depends on where you are located and how much gas you use.
Your location matters because of the different ways that the two gases are priced.
For example, in Australia the natural gas retailers add in a Daily Supply Charge.
This charge frequently makes the cost of natural gas higher than LPG - Propane.
It especially makes LPG cheaper for low volume users, as the Daily Supply Charge can total to more than $400 per year.
Which Burns Hotter Liquid Propane (LPG) or Natural Gas?
LPG burns slightly hotter than natural gas.
LPG - propane - burns ar 1967ºC or 3573ºF.
Natural gas burns at 1950ºC or 3542ºF.
Is Methane More Flammable than Propane?
Methane has an autoignition temperature of 537°C (999°F)
Propane has an autoignition temperature of 470°C (878°F)
The autoignition temperature is the lowest temperature at which a substance spontaneously ignites in air, with no other ignition source.
So, based on their respective autoignition temperatures, propane is more flammable than methane because it spontaneously ignites at a lower temperature.
Is Methane Flammable Without Oxygen?
Methane will not burn without oxygen.
In fact, the percentages of oxygen must be within methane's limits of flammability, which are 4.4% to 17%
LPG Needs More Oxygen
LPG Density is Greater than Natural Gas
LPG (Liquefied Petroleum Gas)
What are Natural Gas Liquids – NGLs?
Natural Gas Liquids – NGLs – are heavier gaseous hydrocarbons that are included in the raw natural gas stream from the wellhead.
NGLs include propane, butane, isobutane, ethane, ethene, propene, isobutene, butadiene, pentane, and pentene and pentanes plus.
Pentanes Plus is a mixture of liquid hydrocarbons, mostly pentanes and heavier. Natural gasoline is the largest component of pentanes plus.
Raw natural gas also contains impurities including water vapour, hydrogen sulphide (H2S), carbon dioxide, helium, nitrogen, and other compounds that must be removed.
Propane, butane and isobutane are the three gases that are typically sold as LPG – Liquefied Petroleum Gas.
Propane is the gas that is supplied to virtually all homes and most businesses that purchase LPG in Australia.
Butane is supplied to certain businesses that specify Butane, as opposed to Propane.
Butane has some specific applications where it has advantages over Propane.
These include greenhouse applications and use as a propellant in aerosols.
The chemical formula for Butane is C4H10.
Percentage of Propane and Butane in LPG
LPG can vary from 100% propane to 100% butane.
The determining factor is primarily the availability of each where you are located.
Different countries and regions have varying access to the supply of each gas.
Autogas (Propane/Butane mix)
Types of Natural Gas (Methane & NGLs)
When it is extracted from the ground it may also contain Ethane, Propane, Butane, and Pentane.
The natural gas liquids - NGLs - are separated out for individual distribution.
Natural Gas - Methane - Uses
How Do We Get Natural Gas
Natural gas is a fossil fuel.
It is formed over millions of years from decayed biomass subject to heat and pressure.
So, natural gas is found deep underground in various rock formations.
It is accessed by drilling deep wells.
The "wet" gas that comes from the well must be processed to separate out the natural gas liquids, like LPG, as well as water and other impurities.
Finally, the dry gas is passed through the gas pipelines that deliver it to our homes and businesses.
Natural Gas Composition
Natural gas is primarily methane.
Methane molecules consist of hydrogen and carbon, with a formula of CH4.
As noted previously, raw natural gas may include propane, butane, isobutane, ethane, ethene, propene, isobutene, butadiene, pentane, and pentene and pentanes plus.
Impurities such as water vapour, hydrogen sulphide (H2S), carbon dioxide, helium and nitrogen are also found in raw natural gas and must be removed.
Methane Propane Butane - Is There Methane in Propane or Butane?
There is no methane in propane or butane.
Methane, butane and propane are three distinctly different gases.
Simulated Natural Gas
Simulated Natural Gas – SNG – is produced by mixing vaporised LPG with compressed air.
SNG can be used in place of natural gas, as it has virtually identical combustion characteristics.
It can be used alone or mixed with regular natural gas.
No changes are required in burners, regulators or gas jets.
Simulated natural gas has a number of names.
In addition to SNG, it is also called propane-air and LPG-air.
Pictured below is a simulated natural gas installation:
CNG Composition (Compressed Natural Gas)
LNG (Liquefied Natural Gas)
Methane gas is processed into LNG by cooling it to −161°C, at which point it becomes a liquid.
This reduces the volume of the natural gas by a factor of more than 600 times as it goes from its gaseous state to liquid.
That's like going from a beach ball to a ping pong ball.
This reduced volume facilitates economical transport by sea or road.
Common LNG uses include industrial applications and long haul trucking.
The technology involved with LNG is generally not cost effective for small volume users, such as homes and small businesses.
For more information, please visit the Elgas LNG web site.
What is LPG?
LPG is the acronym for Liquefied Petroleum Gas
LPG is used for heating our homes & hot water, cooking our food, powering our BBQs & fuel our cars.
It also powers many business and agricultural processes.
Learn more about this amazing transportable gas that comes in a bottle...
How Does LPG Work?
LPG is stored under pressure, as a liquid, in a gas bottle.
It turns back into gas vapour when you release some of the pressure in the gas bottle by turning on your appliance.
Almost all of the uses for LPG involve the use of the gas vapour, not the liquefied gas.
What is LPG made of: LPG Composition
Where does LPG come from?
LPG is not made or manufactured, it is found naturally in combination with other hydrocarbons.
LPG is produced during natural gas processing and petroleum refining.
Once refined, LPG is stored as a liquid under pressure in gas bottles or tanks.
LPG processing involves the separation and collection of the gas from its petroleum base.
About 60% is produced from the natural gas stream that comes out of the wellhead.
The other 40% is produced during the crude oil refining process.
LPG is isolated from the hydrocarbon mixtures by its separation from natural gas or by the refining of crude oil.
Natural gas liquids (NGL) range from 1% to 10% of the natural gas flow.
Similarly, LPG produced from crude oil refining constitutes between 1% and 4% of the crude oil processed.
Both processes begin by drilling oil wells.
Following its refinement, LPG is stored and distributed as a liquid under pressure until used, at which point it is utilised as either a liquid or a gas (vapour).
Refined from Oil & Natural Gas
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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.