Well-to-Tank Carbon Intensity Variability of Fossil Marine Fuels: A Country-Level Assessment

The transition toward a low-carbon maritime transportation requires understanding lifecycle carbon intensity (CI) of marine fuels. While well-to-tank emissions significantly contribute to total greenhouse gas emissions, many studies lack global perspective in accounting for upstream operations, transportation, refining, and distribution. This study evaluates well-to-tank CI of High Sulphur Fuel Oil (HSFO) and well-to-refinery exit CI of Liquefied Petroleum Gas (LPG) worldwide at asset level. HSFO represents traditional marine fuel, while LPG serves as potential transition fuel due to lower tank-to-wake emissions and compatibility with low-carbon fuels. Using OPGEE and PRELIM tools with R-based geospatial methods, we derive country-level CI values for 72 countries (HSFO) and 74 countries (LPG), covering 98% of global production. Results show significant variation in climate impacts globally. HSFO upstream CI ranges 1-22.7 gCO2e/MJ, refining CI 1.2-12.6 gCO2e/MJ, with global volume-weighted-average well-to-tank CI of 12.4 gCO2e/MJ. Upstream and refining account for 55% and 32% of HSFO well-to-tank CI, with large exporters and intensive refining practices showing higher emissions. For LPG, upstream CI ranges 0.9-22.7 gCO2e/MJ, refining CI 2.8-13.9 gCO2e/MJ, with volume-weighted-average well-to-refinery CI of 15.6 gCO2e/MJ. Refining comprises 49% of LPG well-to-refinery CI, while upstream and transport represent 44% and 6%. Major players include China, United States and Russia. These findings reveal significant CI variability across countries and supply chains, offering opportunities for targeted emission reduction policies.