*3.1. Goal and Scope Definition*

The research provides the holistic and practical examination of environmental impacts for operating the LNG- and MGO-fueled vessel in South Korea. The life cycle of the fuels is divided into three phases. Figure 3 illustrates system boundaries of the phases.


For delivering the extracted natural gas to the final use, several processes and utilities are required. The extracted natural gas is transported using pipelines to purification and liquefaction facilities after production process. The liquefied natural gas is transported by LNG carrier vessels to the LNG terminal and storage facilities of the local industry. The LNG bunker barge or truck delivers the stored LNG to the tank of LNG-fueled ship finally. The stages up to this point are called Well to Tank (WtT) phase. The next stage which means fueled vessel operation is the Tank to Wake (TtW) phase. Otherwise, once the crude oil is extracted, through the production and processing, the crude oil is transported to a refinery in a local oil consuming industry from the oil producing country by pipeline and oil tanker (oil tanker is used only if direct pipeline is not connected between the two region). The refined fuels are delivered to the oil bunkering terminal, and the stored oil in the bunkering terminal is consumed for the ship during voyage at sea.

**Figure 3.** Life cycle of LNG fuel and oil-based marine fuel.

In addition, this research was dealt with under the following conditions.


3. Materials and emissions associated with constructing oil and gas facilities (oil extraction, refinery plants, relevant systems, etc.) are not considered in this study. The transport process for energizing the facilities are also excluded.
