Liquid methane is regasified in order to be sent into the pipelines for consumer use.
Converting liquid methane back to its gaseous form is one of the last steps in the logistical process for liquefied natural gas, or LNG. In the earlier stages of this chain, methane gas is liquefied into a readily transportable form. After being shipped and unloaded at so-called regasification terminals, the LNG is reconverted to gas. Regasification itself is a simple concept: Heat the LNG until it turns into gas. The challenge is offload the LNG to be processed at these stations. Sometimes, LNG is diverted to tankers and floating mooring stations before being regasified.
Instructions
1. Prepare LNG for shipment. It will have previously been liquefied from methane gas at liquefaction plants. Methane, as the main component of natural gas, needs pipelines for it to be transported in its gaseous form. Because transport as a gas is not always feasible, liquefying the methane makes it easier to travel. Liquefying involves cooling the methane to minus-161.5 degrees Celsius. In liquid form, methane takes up 600 times less volume than an equivalent quantity of gas. This allows the methane to be shipped as cargo on refrigerated vessels.
2. Transport LNG on specially designed ships called "LNG carriers" which will be double-hulled to protect the cargo and prevent leakage. Ships may carry LNG directly to shore or transfer LNG onto another ship. Ship to ship transfer is a relatively new method, with some modified LNG tankers capable of regasifying LNG on board, discharging gaseous methane directly into pipelines, or discharging LNG onto floating facilities where cryogenic pipelines will send it onshore for regasification. Alternately, move LNG on land via specially designed trucks and rail cars.
3. Receive LNG at regasification terminals either onshore or on ship. Ships, in turn, may transfer LNG to other ships, store it on-board, or divert the LNG to floating stations.
4. Store the LNG. When the LNG is unloaded at its destination, it may be not required right away, and is kept in storage tanks until needed. These tanks may be double-walled or kept underground for increased insulation. In addition to being stored onshore, LNG can also be held in offshore mooring facilities away from ports and sent by pipeline to a regasification facility on land.
5. Vaporize the LNG. Pump the LNG through tubular heat exchangers, which will raise the temperature. Heat the LNG from minus-161.5 C -- its temperature in the liquid state -- to 5 C, which will reconstitute it to its gaseous form. Seawater or heated water can help keep the exchangers warm.
6. Send the gaseous methane into the pipeline grid. Regasified natural gas can now be sent to pipelines for distribution to power plants and consumers.
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