LNG is basically the seaborne transportation of natural gas in liquid form. Liquefying the product reduces its volume about 600 times. LNG mostly contains methane (CH4) which has a boiling point of around minus 161 degrees Celsius, which therefore demands LNG carriers to be sophisticated vessels with double-hull special design and insulated storage tanks.
An LNG ship-to-ship transfer is the trans-shipment of LNG cargo from one vessel to another. The delivering LNG carrier moors alongside the receiving vessel or unit and the cargo is transferred from one to the other via flexible cryogenic hoses. STS transfers can occur in open water, in a carefully selected location between the ports of loading and destination, or at a GasPort or Gateway terminal.
As global market demand for LNG expanded, the need arose to transfer LNG from larger trading vessels to smaller LNG tonnage to open up markets where either draft or infrastructure limitations exist at receiving locations. Nowadays the procedure is also used to supply floating storage and regasification units (FSRUs) which are moored in a fixed location.
After the LNG has been transported to the required destination, it needs to be heated up to its original gaseous state. This involves the use of a Floating Storage and Regasification Unit (FSRU), which is capable of storing and regasifying LNG on board. It delivers the gas to the shore either via an offshore terminal, which typically includes a buoy and undersea pipelines connected to shore, or via an onshore dockside receiving terminal.
A Floating Storage and Regasification Unit can be:
The latter two are permanently moored at offshore or onshore gas receiving terminals and receive LNG from long-haul carriers via STS transfers.
Floating regasification is a flexible, cost-effective way to receive and process shipments of LNG. It is increasingly being used to meet natural gas demand in smaller markets, or as a temporary solution while building onshore regasification plants. FSRUs can be developed in less time than an onshore facility of comparable size and can also be redeployed elsewhere.
Liquefaction is the transformation of natural gas into liquid form (liquid natural gas or LNG) for seaborne transportation. By liquefying the product at minus 161 degrees Celsius, its volume is reduced by about 600 times.
Floating liquefaction provides barge-based liquefaction plants, allowing to take the process offshore and to exploit natural gas resources at sea. Floating above an offshore natural gas field, the FLNG produces, stores and transfers LNG before gas carriers ship it to markets.