## 1 Introduction  
The shipping sector is an important player in the Indonesian economy because sea transportation is cost-effective. Its growth is impacted by indigenous and international regulatory bodies such as IMO. However, the current regulatory standard adopted by IMO is emission control from the vessel's exhaust. Ref. [1] [PERSON] et al. stated that the increased demand for energy triggers the production of greenhouse gases (GHGs) in enormous quantities. GHGs are obtained from burning fossil fuels, which ultimately cause global warming. Since the implementation of emission control by IMO, several studies have been carried out on alternative fuels, and presently, various types are available in the market. Vessel operators have no choice but to select advanced alternative fuel technology as a management strategy. In terms of sulfur emission, traditional marine fuel is influenced by component and hydrocarbon composition and the structure of asphaltenes [2]. The characteristics, both physical and chemical, of asphaltenes will also impact the sulfur content [3]. The major alternative marine fuels in development are hydrogen, LNG, methanol and batteries [4]. [PERSON] stated that transportation modes are significant sources of carbon emission (CO2) [5]. Air pollution containing SO, NOx and particulate emissions significantly impacts human health. In 2015, approximately 32.3 billion tons of CO2 emissions were recorded globally, of which 7.7 billion was obtained from the transportation sector with 5.8 billion tons on land. This is followed by sea transportation and aviation, with approximately 657 million tons and 530 million tons of emissions, respectively. While land transportation contributes a huge amount of CO2, NOx, and particulate emissions, the sea contributes approximately 90% of SOx emissions and impacts the local port [5]. One factor that causes high emissions from vessels is the cheap price and filtering technology of fuel. The use of LNG as alternative marine fuel for decarbonization is implemented in various types of vessels. In South Korea, there was a study on LNG fuel application to new bulk carriers [6]. LNG as a marine fuel is not only implemented in deep-sea shipping, but it has implemented for short-sea shipping or domestic shipping. Fishing vessels are another type of vessel that increase the impact on the environment due to vessel emission, and these types of vessels have started to use alternative marine fuels. The study shows that LNG fuel is a good option for fishing vessels to reduce environmental impact [7]. Another type of vessel that started to use LNG as a marine fuel is the Ro-ro ferry vessel. The conversion of Ro-ro vessels to LNG-fueled vessels will be technically feasible and a good option for local ship operators [8]. In Indonesia, vessel owners are usually more comfortable with conventional fuels such as HFO, MDO or MGO rather than engaging in environmentally friendly vessel operations. According to one study, heavy fossil hydrocarbons are transformed into natural gas, and their constituents can reduce emissions [9]. This flexibility is significant to the termination of dependency on conventional fuel; many countries are yet to develop renewable energy [10]. [PERSON] et al. stated that energy derived from fossil fuels is expensive, impacts the economy, social life protection, welfare, and the educational sector and triggers air pollution [11]. The government needs to create awareness of the importance of environmentally friendly fuel, specifically in the shipping sector. Its realization is bound to impact the economy and social environment for decades significantly. Vessel owners can utilize several fuel alternatives to comply with the IMO regulation. Natural gas is the preferred fuel in this sector due to its innumerable advantages. These include GHGs reduction, better combustion efficiency, attractive cost, and renewability through biomass production [12].