Did you know?
Propane naturally occurs as a gas, but it can be pressurized and/or cooled into a liquid. Because propane is 270 times more compact as a liquid than as a gas, it is transported and stored in its liquid state. Propane becomes a gas again when a valve is opened to release it from its pressurized container. When returned to atmospheric pressure, propane becomes a gas so that it can be burned in stoves and heaters.
Hydrocarbon gas liquids have many uses
Hydrocarbon gas liquids (HGL) are versatile products used in every end-use sector—residential, commercial, industrial (manufacturing and agriculture), transportation, and electric power. The chemical compositions of HGL purity products (HGL streams with at a minimum of 90% of one type of HGL) are similar, but their uses vary.
Hydrocarbon gas liquids, uses, products, and consumers
|HGL||Uses||End-use products||End-use sectors|
|Ethane||Petrochemical feedstock for ethylene production; power generation||Plastics; anti-freeze; detergents||Industrial|
|Propane||Fuel for space heating, water heating, cooking, drying, and transportation; petrochemical feedstock||Fuel for heating, cooking, and drying; plastics||Industrial (includes manufacturing and agriculture), residential, commercial, and transportation|
|Butanes: normal butane and isobutane||Petrochemical and petroleum refinery feedstock; motor gasoline blending||Motor gasoline; plastics; synthetic rubber; lighter fuel||Industrial and transportation|
|Natural gasoline (pentanes plus)||Petrochemical feedstock; additive to motor gasoline; diluent for heavy crude oil||Motor gasoline; ethanol denaturant; solvents||Industrial and transportation|
|Refinery olefins (ethylene, propylene, normal butylene, and isobutylene)||Intermediate feedstocks in the petrochemical industry||Plastics; artificial rubber; paints and solvents; resins||Industrial|
Propane is used as a fuel and is used to make chemicals
Most of the propane consumed in the United States is used as a fuel, generally in areas where the supply of natural gas is limited or not available. This use is highly seasonal, with the largest consumption occurring in the fall and winter months. Propane sold as a fuel for the consumer market is generally defined as HD-5, which contains a minimum of 90% propane by volume, with small quantities of other hydrocarbon gases. HD-10, which contains up to 10% propylene, is the accepted standard for propane in California.
There are two general market categories for propane: consumer (primarily as fuel) and nonconsumer (primarily for nonfuel or feedstock uses). There are four major consumer uses of propane:
- In homes, for space heating and water heating; for cooking; for drying clothes; and for fueling gas fireplaces, barbecue grills, and backup electrical generators
- On farms, for heating livestock housing and greenhouses, for drying crops, for pest and weed control, and for powering farm equipment and irrigation pumps
- In businesses and industry, to power fork lifts, electric welders, and other equipment
- As a fuel for on-road internal combustion engine vehicles such as cars, school busses, or delivery vans, and non-road vehicles such as tractors and lawn mowers
The nonconsumer market for propane is the petrochemical industry. The primary use of propane in the petrochemical industry is as a feedstock, along with ethane and naphtha, in petrochemical crackers to produce ethylene, propylene, and other olefins. Propane can also be used as a dedicated feedstock in the petrochemical industry for on-purpose propylene production. Propylene and the other olefins may be converted into a variety of products, mostly plastics and resins, and also glues, solvents, and coatings.
Ethane is mainly used to produce ethylene, a feedstock to make plastics
Ethane is mainly used to produce ethylene, which is then used by the petrochemical industry to produce a range of intermediate products, most of which are converted into plastics. Ethane consumption in the United States has increased over the past several years because of its increased supply and lower cost relative to other petrochemical feedstocks like propane and naphtha. Ethane can also be used directly as a fuel for power generation, either on its own or blended with natural gas.
Because demand for ethane is almost entirely in the petrochemical sector, and because this product is difficult to transport by any mode other than in dedicated pipelines, supply and demand for ethane must be closely matched. The increase in the supply of ethane starting in 2008, along with other natural gas plant liquids (NGPL), has resulted in some natural gas processors choosing not to recover the ethane that is produced with raw natural gas. Instead, this ethane is left in the natural gas that enters the interstate natural gas pipeline system. This process is referred to as ethane rejection, because the producer rejects the ethane stream into the dry natural gas instead of recovering it along with other HGL.
The presence of ethane in dry natural gas boosts its heat value—calculated in British thermal units (Btu) per standard cubic foot of gas (Btu/scf)—above the heat value of methane (CH4), which is approximately 1,010 Btu/scf. Most of the additional heat content of pipeline-delivered natural gas above the 1,010 Btu/scf level can generally be attributed to the ethane contained in the natural gas transported in pipelines. The U.S. Energy Information Administration publishes the heat content of natural gas delivered to consumers in each state. Not only does the petrochemical industry consume ethane, but so does every natural gas consumer in the United States to some degree.
Butanes: normal butane and isobutane are mostly used as blending stocks for gasoline
Although some normal butane is used as a fuel for lighters, most of it is blended into gasoline, especially during the cooler months. Because demand for isobutane exceeds supply, normal butane is also converted into isobutane through isomerization. Normal butane can also be used as a feedstock in the petrochemical industry. When normal butane is used in petrochemical cracking, the process yields (among other chemicals) butadiene, which is a precursor to synthetic rubber.
Isobutane, whether from natural gas plants, refineries, or isomerized from normal butane, is used to produce alkylates, which increase octane in gasoline and control the volatility of gasoline. High-purity isobutane can also be used as a refrigerant.
Natural gasoline is used in fuels and in oil transportation
Natural gasoline (also known as pentanes plus) can be blended into the fuels used in internal combustion engines, particularly motor gasoline. In the United States, natural gasoline is added to fuel ethanol as a denaturant to make the ethanol undrinkable (this is required by law). Some ethanol producers use natural gasoline to make E85.
About half of U.S. natural gasoline production is exported to Canada where it is used as a diluent (to reduce viscosity) for heavy crude oil, so that the crude oil can be more easily moved in pipelines and railcars.