What is Lng? Turning Natural Gas into Liquid

The world’s population is growing and, for many, living standards will continue to improve. As a result, global energy demand is expected to double by 2050 when compared to 2000. To help meet this demand, gas will form an increasingly important role. Natural gas is plentiful, and it’s the cleanest-burning fossil fuel. But some natural gas resources are in remote locations: transporting the gas long distances by pipeline can be costly and impractical. The solution? We liquefy the gas by cooling it, which shrinks its volume for easier, economical and safe transportation by ship. So, how is liquefied natural gas produced? Natural gas extracted from the ground, contains impurities, water and other associated liquids. First it is processed to clean it. It goes through a series of pipes and vessels where gravity helps separate the gas from some of the heavier liquids. Other impurities are then stripped out. The natural gas passes through a water-based solvent that absorbs carbon dioxide and hydrogen sulphide. These would otherwise freeze when the gas is cooled and so cause blockages. Next any remaining water is removed, as this would also freeze. Finally, remaining lighter natural gas liquids – mainly propane and butane – are extracted to be sold separately or used as refrigerant later in the cooling process. Traces of mercury are also filtered out. Now the purified natural gas – methane with some ethane – is ready to be liquefied. This happens in heat exchangers. A coolant, chilled by giant refrigerators, absorbs the heat from the natural gas. It cools the gas to –162°C, shrinking its volume by 600 times. This turns it into a clear, colourless, non-toxic liquid - liquefied natural gas, or LNG – that is much easier to store and transport. The LNG is kept in insulated tanks until it is ready for loading into a specially designed LNG ship or carrier. When the ship arrives at its destination, the LNG is transferred to a re-gasification plant where it is heated, returning it to its gaseous state. The gas is then transported via pipelines to customers, providing energy for homes and industry. Shell continues to help meet growing energy demand with cleaner-burning natural gas.