What is Liquified Petroleum Gas or LPG? (PDF)

Liquified Petroleum Gas or LPG is a non-renewable source of energy. It is the backbone of cooking, transport, heating, and industry for millions of people worldwide. It is an outstanding upgrade to air quality, efficiency, and climate friendliness as compared to other traditional fuels. It is a responsible source of energy.

The name sounds a bit contradictory as to how can something be both gas and liquid. Because the first one can fly in the air and the second one can splash in a pool. In simple terms, if you see, you will find LPG as a gas under normal pressure and temperature in your living room or garden. But it changes into liquid form when put under pressure or it is cooled down.  

Liquified Petroleum Gas is extracted from crude oil and natural gas. It is composed of hydrocarbons containing some carbon atoms maybe three or four. It is a flammable mixture containing hydrocarbon gases Propane (C3H8) and butane (C4H10) are the normal components of liquefied petroleum gas. Other hydrocarbons in small concentrations may also be present. It is a flammable mixture containing hydrocarbon gases that are used as fuel in heating appliances, vehicles, and cooking equipment. It contains 48 percent propane, 50 percent butane, and 2 percent pentane.

What is LPG?
Fig. 1: What is LPG?

Varieties of LPG that are bought and sold include mixes that contain mostly propane and butane and also sometimes include mixes of both propane and butane. In the areas of the northern hemisphere winter, mixes of more propane are found whereas, in summer, it contains more butane.

Two grades of LPG are sold in the United States mainly commercial propane and HD-5. Other hydrocarbons such as Propylene and butylenes are also present in small concentrations such as ethane (C2H6), methane (CH4), and propane (C3H8). A powerful odorant known as ethanethiol is added to LPG so that leaks can be detected easily. EN 589 is the internationally recognized European standard. In Australia, liquefied petroleum gas is just propane. In other words, all LPG is not propane but propane is LPG.

Liquefied petroleum gas has an energy content similar to petrol and twice the heat energy of natural gas and it burns readily in the air which makes LPG an excellent fuel for cooking, heating, and automotive use.

Where does Liquefied Petroleum Gas come from?

It all starts with nature. Liquefied petroleum gas was first found in 1910. It was then found that petroleum, diesel, gasoline, and heating oil also contain LPG and this was discovered by the American chemist Dr. Walter O. Snellling. Propane and butane are naturally occurring which make up an LPG.

The majority of liquefied petroleum gas is recovered during oil and natural gas extraction while the remaining 40% is made from waste or renewable vegetable oils or is a co-product of oil refining. As LPG is a fossil fuel, it comes from oil and gas wells. Liquefied petroleum gas is stored in liquid form in a steel container, tank, or cylinder under pressure. The pressure inside the container is dependent on the type of LPG used, be it commercial propane or commercial butane, and the outside temperature.

Characteristics of Liquefied Petroleum Gas

There are some of the features of LPG that make it unique on its own.

  1. When petroleum gas changes from a gaseous to a liquid state, it shrinks significantly. It becomes easy to transport lots of energy in a small space as the volume of the liquid is only 1/250 of the gas.
  2. When the liquid inside the cylinder is heated up or when we release the pressure by opening the valve, the liquid changes into vapor form.
  3. The liquid which is turned into vapor is heavier than air. In the case where a cylinder or tank is leaking then it will first change into vapor and then slowly start spreading close to the ground.
  4. Chemically, liquefied petroleum gas is made up of propane, butane, or a mix of the two, and also it contains hydrogen and carbon atoms.

Why choose LPG?

Characteristics of LPG
Fig. 2 Characteristics of LPG

There are several reasons why one should choose LPG and there are a thousand applications that run on LPG. The list is long and includes everything from hot air balloons to cars and heating and BBQs. In other words, it is an extremely versatile fuel. It is used all over the world by millions of people for different purposes with the same result.

The production of LPG globally has increased to 300 million tons per year. In the case where half of its demand comes from the domestic sector using the same for cooking or heating. There are several reasons why one should choose LPG and these are as follows:


This is one of the outstanding qualities of LPG. It is one of the most flexible fuels without any comparison and due to its many applications, it is often referred to as a multipurpose form of energy.

Versatile uses of LPG
Fig. 3: Versatile uses of LPG


LPG is packed with energy. It is extremely efficient. As compared to other energy fuels such as petrol, diesel, coal, and natural gas, it is richer in energy. It has a higher calorific value. In other words, when you set an LPG on fire, the flame temperature will be drastically higher as compared to other fuels which means this results in higher efficiency with a rising temperature.

 As compared to other traditional fuels, LPG is five times more efficient. Hence using an LPG makes it the best way to use most of the planet’s resources. LPG’s high efficiency is one of the most unparallel advantages for both planet and people which makes it one of the best reasons to choose. LPG always keeps its power for good whereas other traditional fuels deteriorate over a period of time.

Easy Storage and Transportation

LPG can be easily stored and transported from one place to another thereby making it more flexible and practical. The refillable cylinder or tanks are some of its storage options either above or under the ground. For cooking, cylinders are used while cylinders are used for applications where a constant supply of energy is required.

There is a wide variety of packaging and transportation options available these days. LPG can be transported by sea, rail, or by road to people who need it. It can travel freely unlike natural gas and electricity that is tied up through wires or lines which requires a complicated infrastructure setup. The reason it is easily accessible to people everywhere is that it can be easily transported to any place be it on mountains, on islands, remotest areas, or far away communities. It is the only sustainable form of energy.

Environmentally friendly

LPG is also an environment-friendly fuel. The sum of its greenhouse gas emissions by looking at its carbon footprint, liquefied petroleum gas stands out as one of the cleanest conventional fuels. LPG is described as an important vehicle in the path toward a clean and viable energy fuel.

Along with natural gas, LPG can create a sustainable way forward in combination or directly with renewable sources of energy like wind and solar energy. Nowadays a new product has entered the market known as Bio LPG to make LPG’s quality even better. Bio LPG functions just like a normal LPG. Bio LPG is extracted from food waste and vegetable oils and also emits less carbon dioxide. Indoor and outdoor air quality is improving day by day by using environment-friendly LPG.

Comparison of LPG with other fuels.

  • LPG is an efficient and sustainable form of energy as compared to other fuels.
  • Only a little amount of LPG creates a lot of energy and emits a lesser amount of carbon dioxide and other greenhouse gases.
  • Heating oil and coal are typically used for cooking purposes and wood is used in developing countries for cooking purposes.
  • This makes LPG a great alternative to all the other resources.
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Anu Sharma

I am a piping stress engineer with 7+ yrs experience. I work in a reputed MNC in Delhi NCR. I will share my knowledge and experience with you on this platform.

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