By Marie‑Luise Blue
Updated Mar 24, 2022
Propane accounts for roughly 4 % of the United States’ energy consumption, according to the National Propane Gas Association. It powers homes, farms, industry, and even vehicles, offering a clean‑burn alternative to gasoline.
As a hydrocarbon, propane is a naturally occurring compound found alongside natural gas and petroleum deposits. It is typically isolated as a by‑product of natural‑gas processing and petroleum refining. At room temperature and atmospheric pressure, propane is a gas, but it liquefies under moderate pressure or lower temperatures, making it ideal for storage and transport.
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During natural‑gas processing, liquid hydrocarbons are separated from the raw stream. Fractionation, absorption in oil, and adsorption onto surface‑active agents or refrigeration remove propane (and butane) to prevent condensation in pipelines. Unprocessed natural gas contains about 90 % methane and only 5 % propane; roughly half of the U.S. propane supply originates from this process. Because liquid propane is 270 times denser than its gaseous form, it is stored and shipped as a liquid.
Liquefied petroleum gases (LPG) arise at various stages of petroleum refining. Propane and butane typically make up 1–4 % of the output of a processed crude oil stream. Fractional distillation under pressure—known as stabilization—allows lighter hydrocarbons like propane to rise to the top layer, where they are collected. The exact yield depends on the refinery’s configuration and operating conditions.
For efficient storage and distribution, propane must be purified to remove impurities such as ethane, propene, and pentene. Liquefaction is carried out at specific temperatures and pressures that comply with industry standards. Once liquefied, propane is transported via underground pipelines to storage facilities, then moved by rail, truck, or barge to local distributors.
While propane burns cleaner than gasoline—producing fewer harmful emissions—its status as a fossil fuel limits its environmental benefits. Researchers are investigating renewable routes, such as converting vegetable oil, sugarcane, switchgrass, or microbial biomass into propane. These synthetic or biopropane streams could reduce greenhouse‑gas emissions and bolster U.S. energy independence, without major changes to existing refining infrastructure.
