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Completing the puzzle

Guidelines for assessing gas quality have been a missing piece in the ‘LNG as a fuel’ puzzle until now…

Words: Kevin Tester

Liquefied natural gas (LNG) has proved to be a viable option as a fuel for ships. Its key differences from traditional marine fuels include a low flashpoint and cryogenic temperature, but also the important fact that the supply of LNG as bunker fuel is not yet widespread or routine. Therefore, it’s essential to understand the many different risks involved in operations using LNG as opposed to other conventional fuels. Until now, there’s been no international standard describing the methods for financial measurements and suitability for LNG as a marine fuel, despite the growing international market for small-scale LNG bunkering. DNV GL’s updated Recommended Practice (RP) is one of the first industry guidance documents on how to perform quality measure- ments and quantity metering of LNG fuel supply. To support the burgeoning

market for LNG-as-a-fuel, the classification society DNV GL has updated its RP for Development and Operation of Gas Bunkering Facilities (DNVGL-RP-G105). It now includes a section dedicated to determining LNG quantity and its properties. The objective is to

assist operators in addressing the large spread in properties, density and the calorific value among the available global LNG sources. Through its recommendations,

DNV GL seeks to facilitate the ‘monetisation of the LNG small-scale distribution network and infrastructure’. In other words, it wants to foster a more transparent market and to safeguard sustainable growth. The RP examines the business

impact of proper financial measurement, as gas from different sources with various compositions can result in substantial variation in energy content and burning properties. This may have implications for billing, the expected voyage distance and safety of operations. “The specification of LNG and

required metering methodology have, until now, been the missing pieces in the LNG-as-fuel puzzle,” says Martin Layfield, a specialist in the emerging LNG market at DNV GL. “This new RP completes the

picture and will provide a level playing field for the billing process of LNG and documentation around the gas quality.” The RP focuses on four main

elements – safe design and operation, safety management systems, risk assessments and now also includes coverage on gas quality and quantity metering. The RP is in accordance with, but further elaborates on the ISO/TS 18683 Guidelines for systems and installations for supply of LNG as fuel to ships, with a focus on bridging the gap between the rules for the receiving ship and the bunker supplier – such as national or port regulations and rules for LNG bunker vessels. The documentation also

covers the development and operation of LNG bunkering facilities, including simultaneous operations on land and water. It’s applicable to truck-to-ship, terminal-to-ship and ship-to-ship bunkering scenarios, as well as inland shipping and vessels that aren’t covered by IMO regulations. “LNG’s use is set to soar over

the next decade. However, by its nature, its risk properties differ from traditional fuel, so the updated RP also elaborates on how to establish proper safety zones including guidance on techniques and other risk methodologies,” adds Layfield. Furthermore the RP addresses

risk evaluations for the planning phase of new LNG bunkering facilities. A bow-tie model of risk management is recommended. This serves as a technique to assess if adequate barriers – both operational and technical – are in place to mitigate different unplanned hazardous scenarios. Management of the risks

associated with LNG continues to be developed, especially as the fuel supply is not yet widely carried out on a routine basis around the world. This is addressed by DNV GL in an ongoing Joint Industry Project (JIP) to enhance understanding of the risks and hazards in small-scale LNG bunkering stations which aims to provide experimental data to validate and improve physical models and answer safety-related questions. The JIP will ultimately result in rigorous standards for safe design, siting, construction and operation of small-scale LNG bunkering stations.

To download a copy of the RP document , visit: www. download-dnvgl-rp-g105.html


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