Natural gas has become one of the most important sources of energy in the world, contributing significantly to the global energy mix. The rise of natural gas can be attributed to its relative cleanliness compared to other fossil fuels, its efficiency in power generation, and the abundance of gas reserves, particularly in North America, Europe, and the Middle East. As the demand for energy grows, so too does the importance of an efficient and effective natural gas delivery system.
The natural gas delivery system is a vast network of interconnected pipelines, processing plants, storage facilities, and distribution hubs. This system ensures that natural gas can be delivered to power plants, industrial facilities, and homes safely and on time. From extraction at the wellhead to the final point of consumption, every stage in the natural gas supply chain is carefully monitored and managed.
In this article, we will explore each element of the natural gas delivery system in detail. We will start by understanding how natural gas is extracted and processed before moving on to its transportation through pipelines. We will then examine the role of storage, distribution, and how natural gas reaches end users.
How Natural Gas Is Extracted
Before natural gas can be delivered to consumers, it must first be extracted from the earth. Natural gas is often found in underground reservoirs, typically located in rock formations. These formations can be either conventional or unconventional, which affects how the gas is extracted.
Conventional Natural Gas Extraction
Conventional natural gas is typically found in large underground reservoirs, where it is trapped beneath a layer of impermeable rock. To extract the gas, drilling rigs are used to create wells that reach down into the reservoir. Once the well has been drilled, the natural gas flows to the surface under its own pressure, often along with crude oil or other hydrocarbons.
Unconventional Natural Gas Extraction
Unconventional natural gas, such as shale gas, coalbed methane, and tight gas, is found in more difficult-to-reach rock formations. Extracting this gas requires more advanced techniques, such as hydraulic fracturing (fracking) and horizontal drilling. Fracking involves injecting a mixture of water, sand, and chemicals into the rock to create fractures through which the gas can flow. Horizontal drilling allows access to a larger area of the gas reservoir without drilling multiple vertical wells.
Once natural gas is extracted, it is usually a mixture of hydrocarbons, water vapor, carbon dioxide, and other impurities. Before it can be transported, the gas must be processed to remove these impurities and separate the valuable methane from other components.
Natural Gas Processing
The natural gas that comes out of the ground is not suitable for immediate use. It contains a range of impurities and byproducts that must be removed before it can enter the pipeline network. Processing plants are responsible for cleaning the gas and making it ready for transportation.
Separation of Liquids and Solids
The first step in natural gas processing is to remove any liquid hydrocarbons and water from the gas. This is done using mechanical separators, which use gravity to allow the heavier liquids to settle at the bottom while the gas rises to the top. The liquids, known as natural gas liquids (NGLs), can be processed further and sold as valuable byproducts, such as propane, butane, and ethane.
Removal of Impurities
After the gas has been separated from liquids, it still contains impurities such as carbon dioxide (CO2), hydrogen sulfide (H2S), and water vapor. These impurities can cause corrosion in pipelines and reduce the quality of the gas. To remove them, the gas is treated using various chemical processes. For example, CO2 can be removed using amine gas treating, while water vapor is removed through a process called dehydration.
Odorization
Once the gas has been cleaned and purified, a small amount of odorant is added to it. Natural gas is colorless and odorless in its natural state, which makes it difficult to detect leaks. To enhance safety, an odorant, typically a sulfur-containing compound such as mercaptan, is added to give the gas a distinctive “rotten egg” smell. This helps people detect leaks and avoid potential accidents.
See also: How Is Natural Gas Extracted?
Transportation of Natural Gas
The next step in the natural gas delivery system is transportation. Natural gas is primarily transported through pipelines, though in some cases it may be shipped as liquefied natural gas (LNG). The pipeline network is vast, extending thousands of miles across continents, and is carefully regulated to ensure the safety and efficiency of the system.
Transmission Pipelines
Transmission pipelines are large-diameter, high-pressure pipelines that transport natural gas from processing plants to storage facilities and distribution networks. These pipelines are often buried underground and built to withstand high pressures, typically ranging from 200 to 1,500 psi (pounds per square inch). Compressors are strategically placed along the pipeline to maintain pressure and keep the gas flowing at a constant rate.
Compressor Stations
Compressor stations are a critical component of the pipeline network. As natural gas travels through a pipeline, friction and elevation changes can cause a drop in pressure. To keep the gas moving, compressor stations are installed at regular intervals along the pipeline. These stations use large engines or turbines to compress the gas, increasing its pressure and ensuring it continues to flow toward its destination.
LNG Transportation
In cases where natural gas needs to be transported over long distances, such as across oceans, it is often converted into liquefied natural gas (LNG). To do this, the gas is cooled to around -260°F (-162°C), at which point it becomes a liquid. LNG takes up about 1/600th of the volume of natural gas in its gaseous state, making it much more efficient to transport. Once the LNG reaches its destination, it is regasified and injected into the local pipeline network.
Natural Gas Storage
Natural gas storage is essential to ensure a stable supply, particularly during periods of high demand. Storage facilities allow excess gas to be stored during times of low demand (such as summer) and withdrawn during peak demand periods (such as winter). There are several types of natural gas storage facilities, each with its own advantages.
Underground Storage
The most common form of natural gas storage is underground storage. There are three main types of underground storage facilities: depleted gas reservoirs, aquifers, and salt caverns.
Depleted Gas Reservoirs: These are former natural gas fields that have been emptied of their gas reserves. They are ideal for storage because the geology of the reservoir is already proven to hold natural gas. Depleted gas reservoirs can hold large volumes of gas and are the most commonly used storage facilities.
Aquifers: Aquifers are underground, water-bearing formations that can be used to store natural gas. These formations require more preparation and infrastructure than depleted reservoirs, but they are useful in areas where other storage options are limited.
Salt Caverns: Salt caverns are created by injecting water into underground salt formations to dissolve the salt and create a large, empty space. Salt caverns are highly secure and provide excellent containment for natural gas. However, they tend to have smaller storage capacities than other types of underground facilities.
Above-Ground Storage
While most natural gas is stored underground, there are also above-ground storage options. These include LNG storage tanks and pressurized vessels. LNG storage tanks are used to store liquefied natural gas at low temperatures, while pressurized vessels can store smaller quantities of compressed natural gas (CNG).
Distribution of Natural Gas
After natural gas is processed, transported, and stored, it must be distributed to end users. The distribution network consists of smaller-diameter, lower-pressure pipelines that deliver gas to homes, businesses, and industrial facilities.
Local Distribution Companies (LDCs)
Local distribution companies (LDCs) are responsible for managing the final stage of the natural gas delivery system. These companies receive natural gas from the transmission pipeline and deliver it to consumers. LDCs operate in cities, towns, and rural areas, maintaining the distribution network and ensuring a safe and reliable supply of gas.
Pressure Regulation
Before natural gas enters the distribution network, its pressure must be reduced. Transmission pipelines operate at high pressures, but these pressures are too high for use in homes and businesses. Pressure reduction stations are used to lower the pressure of the gas before it is distributed to consumers. Regulators at each point along the distribution system ensure that the gas is delivered at the correct pressure.
End-Use Consumption
The final stage of the natural gas delivery system is consumption. Natural gas is used in a variety of applications, including:
Residential Use: Natural gas is used in homes for heating, cooking, and water heating. It is a convenient and cost-effective energy source for residential consumers.
Commercial Use: Businesses and public buildings use natural gas for heating, cooling, cooking, and powering certain types of equipment.
Industrial Use: Industries use natural gas for a range of applications, including process heating, power generation, and as a raw material for chemical production.
Electricity Generation: Natural gas is a major fuel source for power plants. It is burned in turbines to generate electricity, providing a cleaner alternative to coal.
Conclusion
The natural gas delivery system is a highly efficient and intricate network that involves extraction, processing, transportation, storage, distribution, and final consumption. Each stage of the process is designed to ensure that natural gas is delivered safely, efficiently, and reliably to consumers. Whether it is powering homes, industries, or generating electricity, the delivery system plays an essential role in ensuring that natural gas remains a key part of the global energy mix.
Understanding how the natural gas delivery system works helps to appreciate the engineering and logistical efforts involved in delivering one of the world’s most important energy resources to consumers around the globe.
Related topic:
Where Natural Gas Is Found and How It Is Obtained?
