Liquefied Natural Gas (LNG)
Liquefied Natural Gas (LNG) is a form of natural gas that has been cooled to extremely low temperatures, allowing it to transform from a gaseous state to a liquid. This process, known as liquefaction, enables natural gas to be transported more efficiently, especially in scenarios where building pipelines is impractical due to geographical or political challenges. LNG is derived from various hydrocarbons, including methane, propane, and ethane, which must be separated before liquefaction due to their differing physical properties.
Once liquefied, LNG is stored in specialized containers and transported primarily via large tanker ships, making it one of the safest fuels to transport compared to other fossil fuels. In the event of a spill, LNG evaporates quickly, posing minimal risk to the environment. Upon reaching its destination, LNG is re-gasified and distributed through pipelines to homes and businesses, or it can be liquefied again for future transport.
LNG has a variety of applications, primarily in residential and commercial heating, as well as in fueling vehicles and ships. Although it is recognized for being a cleaner-burning fuel, there are concerns regarding its impact on climate change compared to traditional fuel sources. Overall, LNG plays a significant role in the global energy landscape, addressing the need for efficient and safe energy transportation.
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Liquefied Natural Gas (LNG)
Natural gas refers to a series of combustible gases that occur naturally underground. Natural gas is used as a fuel and is popular throughout the world. To be transported in ways other than through pipelines, natural gas needs to be forced into a liquid form. To accomplish this, natural gas is chilled to extreme temperatures.
Background
People have observed natural gas vents since ancient times. However, the resource was not monetized until 1765 when the British realized that a highly flammable gas produced from coal burned steadily at a consistent brightness. They used it to make gas-powered lighting, creating the world's first streetlights. Wealthier citizens could afford to light their homes with the new technology. Within the century, the technology had spread to America. Baltimore was the first city in the United States to utilize natural gas for lighting.
During the nineteenth century, the first government-owned natural gas company opened in Philadelphia. It distributed gas throughout the city's districts—it was difficult and expensive to transport the gas outside the city. At this time, natural gas was primarily used for lighting.
By the end of the nineteenth century, electricity producers began to compete with natural gas distributors. Electric lights became more popular than gas-powered lights, drastically shifting control of the market. To remain profitable, natural gas companies knew that they would have to find new uses for their product. When Robert Bunsen discovered a way to mix air with natural gas to create an extremely stable, clean-burning flame, natural gas companies quickly capitalized on the opportunity. Natural gas was now safe for cooking and heating. New technological advancements also allowed natural gas flames to be more safely monitored and more precisely controlled.
In the early twentieth century, scientists began to develop an efficient means of transporting natural gas. The first major natural gas pipelines transported natural gas from wells to distributing stations in neighboring cities. In some cases, pipelines shipped the gas more than a hundred miles. Unfortunately, the pipes proved unreliable until after World War II when new welding and metallurgy techniques drastically improved the quality of the pipelines. In the 1960s, the US government built a network of natural gas pipes that crisscrossed the country. This made natural gas available to the masses. Its popularity increased, ensuring that the natural gas industry would continue to thrive far into the future.
Overview
Liquefied natural gas is one of the cleanest, most efficient burning fuels in widespread use. However, it is not always practical to build a pipeline to a new location. Uneven terrain, bodies of water, long distances from wells, and even unstable political situations can make the construction of a pipeline difficult or impossible. In these situations, natural gas producers turn to liquefied natural gas.
Natural gas is obtained and manufactured in a gaseous form. These gases do not exist in a liquid form in nature. However, once scientists realized that all substances have a temperature at which they change physical form, they applied this knowledge to natural gas. When heated to a particular temperature, all liquids break their atomic bonds and turn into a gas. The reverse is also true. When cooled to a certain temperature, all gases compress into a liquid.
Before natural gas can be successfully liquefied, it must be separated into its base components. In their natural states, many natural gases coexist. These include methane, propane, ethane, and n-butane. Because each has a different boiling point and melting point, it must be separated before being liquefied. If these gases were all liquefied at once, some would freeze, making the gases difficult to separate in the future.
Once the gases have been successfully separated, a complex process is used to chill the natural gas. Controlled amounts of pressurized propane are used to gradually cool the natural gas. Then the gas is run over super-cooled liquids, which leech even more heat from it. Finally, nitrogen is used to supercool the already cold gas. At this stage, the natural gas enters a liquid form.
If returned to a neutral area, liquid natural gas reverts to its gaseous form. For this reason, liquid natural gas must be stored in specialized containers. Most of the time, these containers are the size of multi-story buildings. Some are even as wide as a football field.
Then the liquefied natural gas is removed from these containers and shipped across the nation. While some gas is shipped using tanker trucks, most is transported on large tanker ships. Liquefied natural gas is much safer to transport than oil. If it spills on land, it evaporates harmlessly into the atmosphere. If it spills in water, it distributes somewhat evenly in the water before rising and evaporating. Liquefied natural gas spills pose little risk to humans and require little or no cleanup. Additionally, when transported in its liquid state, natural gas will not ignite.
Once the liquefied natural gas arrives at its destination, it needs to be returned to its gaseous state. In most circumstances, the gas is unloaded from its transports in its stable, liquid state. Once inside its new storage tanks, the gas is slowly and carefully warmed. As it warms, it returns to its gaseous state. The natural gas can then be transported to homes and businesses through pipelines or liquefied again for shipping purposes at a later date.
Liquefied natural gas has primarily been used to supply natural gas to residential and commercial facilities. It has also been used to fuel ships, although evidence suggests it has a stronger negative impact on the climate than marine gas oil. Liquified natural gas-fueled vehicles are also available. Manufacturers have produced heavy-duty vehicles such as school and transit buses and refuse trucks and trucks for hauling cargo over long distances because the energy density requires fewer refueling stops.
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