ABSTRACT

The international liquefied natural gas (LNG) trade is a growing sector in the global energy market driven, in part, by the transition from carbon-intensive energy sources such as coal and diesel to lower-carbon alternatives. The emergence of the ‘green LNG’ market, which involves offsetting emissions through carbon credits, highlights the industry’s shift towards sustainability. However, a critical challenge lies in estimating and managing emissions across the entire value chain, particularly in Scope 3 emissions, such as Upstream Transportation and Distribution (Category 4). This study employs a Monte Carlo model implemented in a hydrocarbon management system (EnergySys) to analyse greenhouse gas (GHG) emissions associated with each stage of an LNG voyage from Gladstone Island, Australia, to Himeji, Japan. The analysis incorporates variables such as engine type, voyage duration, fuel consumption and methane slip. Results indicate that the cargo and ballast voyage stages are the largest contributors to total emissions, accounting for over 80% of the journey’s 4193 tCO₂-e. This paper aims to support the understanding of GHG emissions across the various stages of the LNG voyage, providing a structured analytical approach that highlights key emission sources in LNG transportation.