Many people use the terms Natural Gas and Propane interchangeably because they are both used for cooking, heating and transportation to name a few similarities, but are they the same thing? The answer, in short, is not exactly, so let’s explore some of the similarities and differences between them.
Natural gas is a naturally-occurring compound found deep beneath the earth’s surface having been formed over millions and millions of years by decaying plant and animal remains that were buried under enormous pressure and heat. This raw fossil fuel’s primary component is methane gas (CH4) which is composed of one carbon and 4 hydrocarbon atoms. Raw natural gas also consists of an assortment of smaller amounts of other gaseous substances with propane being among them.
Propane is a hydrocarbon compound found within natural gas that, at certain atmospheric pressures, occurs as a gas, and under higher pressures as a liquid, as do its hydrocarbon sibling’s butane and ethane. These hydrocarbon gas liquids (HGL’s) are described as being either light or heavy according to the number of carbon and hydrogen atoms contained in their molecules.
Light or heavy gas?
Propane, known as a “heavy gas,” is composed of three carbon atoms and eight hydrogen atoms (C3H8) that make it “heavier than air,” while natural gas is conversely lighter than air. Propane is one of several components separated from other fossil fuels when the gas/oil hydrocarbon mixture is piped out of a well and into a gas trap. This “trap” essentially splits the mixture into crude oil and "wet" gas which is made up of natural gasoline, liquefied petroleum gases, and natural gas.
Trapping, separating and storing the gases
Gravity plays a role in separating these materials as heavy crude oil sinks to the bottom of the trap prior to being pumped into storage tanks for further refinement, while the "wet" gases (which contain about 90% methane at this stage) come off the top of the trap for further processing. Thereafter propane (and the other LPG’s) are isolated from natural gas using solvents, special filters (membranes) or by cooling the gases as some liquefy much sooner than others. (For example, natural gas turns to liquid when it is cooled to -260 F while while propane liquefies at only -44 F.)
Once separated, both natural gas and propane are typically stored in large, above-ground tanks or in refillable and/or portable bottles. Propane, or LPG as it is commonly known, can be easily converted to liquid if stored in a tank under pressure as in the small white tanks used for outdoor barbeques.
Which is more efficient?
Lastly, when used as a fuel, propane is considered more energy efficient than natural gas because it is typically mixed with oxygen in pressurized tanks that contain less overall propane than oxygen. This mixture, when burned, produces more BTU’s (i.e. heat) using less fuel, obtaining a much higher energy release than natural gas. Moreover, propane is not toxic or damaging and will not harm the environment if it is released into the atmosphere, whereas natural gas is considered one of the “greenhouse gases” due to its high concentration of methane.
Talk to us if you want to learn more about the advantages of propane!