1 Chapter I Introduction I.1 Background As the amount of carbon in the atmosphere increases from an initial 265 parts per million in 1750 to 460 parts per million in 2020 as shown in Figure I.1 below, the earth's surface temperature rises, causing climate change. (NOAA, 2023). The increasing threat of global warming, primarily caused by carbon dioxide (CO2) emissions from burning fossil fuels, has intensified the search for sustainable energy solutions (Estevez et al., 2023). This is particularly crucial for developing nations like Indonesia, which has a large population and a rapidly growing economy. The country has committed to achieving net-zero emissions by 2060, necessitating innovative approaches in the energy sector, a major source of Green House Gases (GHG) emissions (Kanugrahan & Hakam, 2023). Figure I.1 Global Annual Greenhouse Gas Index (NOAA, 2023). One promising avenue is utilizing ammonia (NH3) as an alternative fuel in gas-fired power plants. Ammonia, a carbon-free energy carrier, can be produced from renewable sources such as biomass, solar, and wind energy, and it can be stored and transported relatively easily (Aziz et al., 2020). Co-firing ammonia with natural gas in gas engines has the potential to significantly reduce CO2 emissions while 2 combustion efficiency slightly decreased (Oh et al., 2022). This approach aligns with Indonesia's commitment to reducing greenhouse gas emissions and transitioning towards a more sustainable energy future. Pusat Listrik Tenaga Mesin Gas (PLTMG) Luwuk 40MW is a power plant located in Central Sulawesi, Indonesia, which utilizes a single-fuel gas engine primarily powered by natural gas. Natural gas is widely recognized as a transitional fuel in the shift from fossil fuels to cleaner energy sources (Safari et al., 2019). In 2020, Indonesia had an installed capacity of 1.7GW (PLN, 2021), which resulted in emission of approximately 2.65 million tons of CO2 eq. per year. The co-firing of natural gas with ammonia at the PLTMG Luwuk 40MW presents a viable strategy to accelerate the energy transition. However, the widespread adoption of ammonia as a fuel requires a thorough understanding of the combustion process and its impact on engine performance and emissions (Valera-Medina et al., 2018). Research in this area is crucial to optimize the combustion process, mitigate potential challenges such as NOx emissions, and ensure the safe and efficient operation of gas engines using ammonia-natural gas blends. Therefore, in-depth research on modeling the combustion of ammonia-natural gas mixtures in gas-fired power plants is of paramount importance to support Indonesia's efforts in achieving its net-zero emission target by 2060. I.2 Scope of Study The scope of this study is defined to ensure a more detailed and focused analysis, as follows: 1. The power plant under review is the PLTMG Luwuk 40 MW.