Natural Gas Liquids (NGL): Definition, Types, Examples

What Are Natural Gas Liquids?

Natural gas liquids (NGL) are components of natural gas that are separated from the gas state in the form of liquids. This separation occurs in a field facility or a gas processing plant through absorption, condensation, or other methods. There are several types of natural gas liquids and many different applications for NGL products.

Understanding Natural Gas Liquids

Natural gas liquids are valuable as separate products, and it is profitable to remove NGL from the natural gas. The liquids are first extracted from the natural gas and later separated into different components. Natural gas liquids are hydrocarbons. A hydrocarbon is a molecule composed exclusively of carbon and hydrogen. As hydrocarbons, NGLs belong in the same family of molecules as do natural gas and crude oil.

Types of NGLs and Their Applications

Natural gas liquids are classified based on their vapor pressure:

• Low = condensate
• Intermediate = natural gas
• High = liquefied petroleum gas

Additionally, chemical compositions of NGLs are similar, but their applications vary widely. Specifically, the many uses of natural gas liquids include cooking, space heating, and blending NGLs into fuels for vehicles.

Ethane

Applications of ethane include plastics production and petrochemical feedstock—raw materials fed into an industrial production process to yield a different end product. End-use products include plastics, plastic bags, antifreeze, and detergent.

Propane

Applications and uses of propane include residential and commercial heating, cooking fuel, small stoves, and petrochemical feedstock. Some vehicles also use propane as fuel.

Butanes

Butanes can be blended with gasoline and propane. Products include synthetic rubber for tires and lighter fuel. In its purest form, butane is useful as a refrigerant. Combined with propane, butane becomes liquified petroleum gas (LPG).

Isobutanes

Industrial use of isobutanes can include refinery feedstock and petrochemical feedstock. End-use products include aerosols and refrigerants.

Pentanes

Pentanes are used in natural gasoline and as a blowing agent for polystyrene foam. Pentanes plus, a special category (also known as natural gasoline), is blended with vehicle fuel and exported for bitumen production in oil sands.

Challenges and Opportunities

The U.S. shale boom increased extraction rates of natural gas liquids and NGL extraction is positively related to the price of crude oil. That's because, as the market price of crude decreases, oil, gas, and chemical companies expand their offerings to include NGLs and offset lost revenue.

There have been significant advancements in technologies such as horizontal drilling and hydraulic fracturing techniques, which involve using high-pressured water or liquids to extract gas. As a result, natural gas liquid production has increased steadily. In fact, NGLs provide many natural gas producers with an additional income stream, which can help diversify their revenue.

A challenge with natural gas liquids is that they're expensive to handle, store, and transport compared to refined products because NGLs require high pressure or low temperature to be maintained in their liquid state for shipment and handling. NGLs are also highly flammable and necessitate the use of special trucks, ships, and storage tanks.

The volatility of the natural gas liquids somewhat limits the number of markets available for their use. Also, as production increases, so too does the need for processing plants that separate NGLs from natural gas.

Examples of NGLs

Let's say that a new production facility opened in Texas, whereby drilling for natural gas has resulted in a significant amount of the fuel. The gas is extracted from the well and sent to a production facility to be heated at various temperatures to generate the NGLs ethane and propane.

The ethane is removed from the natural gas stream after it reaches the necessary boiling point, followed by propane, which is a heavier gas resulting in a lengthier boiling process. Once the propane and ethane have been removed from the natural gas stream, in a process called fractionation, the NGLs travel via a pipeline.

Eventually, natural gas liquids are shipped by specialized trucks to commercial businesses, industrial plants, and the local gas company. The propane can be used for residential and commercial heating as well as cooking. Lastly, ethane is used to create plastics such as water bottles and plastic bags.