Ethane is a naturally occurring, colorless, odorless, and highly flammable organic gas. Each molecule consists of two carbon atoms bonded to six hydrogen atoms, making it the second simplest alkane after methane. An alkane is any organic compound that contains solely carbon and hydrogen atoms. Methane has only one carbon atom and four hydrogen atoms per molecule.
Ethane is mainly found in natural gas and as a by-product of petroleum refining. It also occurs as a trace gas in the earth's atmosphere and is found in the atmospheres of the giant planets and Saturn's moon Titan.
Ethane is industrially important mainly as a raw material for producing ethylene, which is a key precursor for manufacturing plastics (mainly the various types of polyethylene, but also polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP) and styrene-based plastics), antifreeze, detergents, and other chemicals. It can also be used as a fuel and a refrigerant, although its use as a fuel is limited due to its greater value as a petrochemical precursor.
The extraction, processing, and use of ethane contribute to environmental degradation in a variety of ways. Perhaps the most harmful effect is the vast output and ever-accumulating volume of plastics that it facilitates.
When released into the air, ethane is rapidly oxidized, leading to the formation of ground-level ozone and carbon monoxide, which contribute to the formation of smog, with its various adverse effects on public health. It also acts as a greenhouse gas, although it is less potent than methane because it remains in the atmosphere for only a few months before breaking down, in contrast to about 10 years for methane.
The largest source of ethane release into the air is the production, processing and transmission of natural gas and oil, at more than 60 percent. Others include the combustion of biofuels, wildfires and other biomass burning, and natural geologic sources, including from volcanic activity and seepage from fossil carbon deposits.
Facilities that process ethane into ethylene emit an array of hazardous air pollutants including benzene, butadiene, carbon dioxide, formaldehyde, nitrogen oxides, particulate matter, toluene, and volatile organic compounds.