The anticipated long-term growth in U.S. natural gas demand will require the construction and operation of both onshore and offshore LNG terminals. Recently, several offshore LNG terminals have been proposed to increase LNG deliveries to market centers where onshore facilities cannot realistically be sited. The technologies and experience developed for offshore oil infrastructure and onshore LNG terminals can be applied to the development and operation of offshore LNG terminals. The proposed offshore LNG terminals benefit from the record of safety and reliability that has been achieved by the offshore oil industry and by onshore LNG terminals around the world. Each of the essential components of Broadwater’s FSRU has been used safely and reliably in both offshore petroleum and onshore LNG terminal operations. The main difference is the scale of the application proposed for Broadwater. Offshore siting innovations for LNG facilities necessitate new rules and guidelines for the design, construction and maintenance of such facilities. Since 1862, ABS has developed such rules and guidelines for the maritime industry. ABS has published a guide for building and classing offshore LNG terminals that puts forth a comprehensive set of criteria.80 The classification process begins with an assessment of design and continues throughout the operational life of the offshore LNG facility. Such oversight ensures the continued adherence to the ABS rules and guidelines and other relevant standards beyond the initiation of service through the installation and operation of the facility.81 LAI’s technology study objectives were threefold: first, to evaluate the various types of offshore LNG facilities; second, to identify the technology limitations of the FSRU, its major components and the YMS; and, third, to assess operational issues with the FSRU and LNG transfer. LAI’s technology review was based on data obtained from the draft and final EISs from other proposed and approved LNG projects, industry LNG technology presentations and papers, and publicly available reports on technology. LAI’s approach to evaluating Broadwater’s technology involved a high level review of each type of offshore LNG facility proposed or operating in the U.S. including gravity-based structures (GBSs), modified LNG tankers unloading to a submerged turret loading buoy, and other FSRUs. LAI also evaluated each of the essential operating components of the FSRU from the perspective of historical use and assessed their appropriateness for the proposed application. The following LNG systems and components were evaluated: containment, regasification (vaporization), cargo transfer, emergency shutdown, boil-off, custody transfer and mooring. 3.1. Offshore LNG Technology Options
An offshore LNG terminal receives LNG from oceangoing vessels, regasifies the LNG either immediately or subsequent to being stored, and delivers the LNG to the onshore market through a subsea pipeline. While offshore applications have been used successfully for a number of different petroleum products, only recently has interest been focused on LNG. Such interest has 80 81
American Bureau of Shipping, “Guide for Building and Classing Offshore LNG Terminals,” April 2004. ABS was selected as the third party Certifying Entity for the Project on February 16, 2007.
been generated by the need to expand the opportunities to meet market requirements in light of sensitive siting and public safety issues. The development and use of offshore facilities is an extension of the industry’s experience over the past several decades from land-based LNG terminals, LNG ship design, and similar floating applications utilized in the petroleum sector, referred to as Floating Production Storage and Offloading (FPSO) units. Offshore LNG import terminals can be grouped into the following five categories, some of which are illustrated in Figure 27. •
Natural Island Facility – A terminal sited...