Risk informed floating storage and re-gasification unit (FSRU) location selection for local natural gas supply

Abstract

In the present energy market due to high demand of liquefied natural gas (LNG) and the limited availability of land-based LNG import terminals, the use of offshore LNG terminals is destined to increase. Such terminals are referred to as LNG floating storage and re-gasification units (FSRUs). An FSRU terminal is a cost-effective and a time-efficient solution to quickly open up supply to onshore users with minimal environmental impact. This work focuses on the selection from a safety point of view of a possible location for an offshore or nearshore FSRU, given alternative candidate locations. For decision making, the maritime and process safety aspects of the LNG resupply operation have to be considered. This involves the approach of an LNG Carrier (LNGC) to resupply the FSRU. The whole resupply process is divided into three consecutive parts, beginning with the LNGC navigating in the inbound channel, going through its berthing operation, and ending with transfer of the LNG. The safety of the third part, the LNG transfer to the FSRU, could be evaluated by means of a quantitative risk assessment. For the maritime operations this was not possible and evaluation had to rely on expert elicitation. To create a comparison basis of navigating, turning and berthing hazards with the risks of the LNG transfer process, a novel safety utility value (SUV) was defined existing of five ranges. Hazard attributes of navigating and of turning and berthing of the maritime operations were identified/confirmed by simulator runs, their importance was ranked, as well as their safe operating ranges determined with the aid of queries to a large group of experts. Importance ranking was based on pairwise comparison judgment, responses aggregated by means of fuzzy number fits, processed in square matrices. Expert elicitation yielded safety attribute values (SAVs) for the five SUV ranges which were statistically treated. QRA provided potential loss of life (PLL) values, which also were converted into SUV ranges. Based on the importance ranking of the three parts and the SUVs, final results were obtained.