The transition toward sustainable and environmentally friendly practices in maritime operations has led to the widespread adoption of cold ironing, or shore power, in port facilities. Cold ironing refers to the practice of supplying electrical power from the shore to vessels while they are docked, allowing ships to shut down their auxiliary engines, thereby reducing air emissions, fuel consumption, and noise pollution. This thesis investigates the economic, and environmental implications of implementing cold ironing systems in ports, Through a combination of case studies, data analysis, and modeling, the research examines the impact of cold ironing on port operations, vessel emissions, and energy consumption. It also explores whether onshore power supply or auxiliary engines is more environmental friendly and cost effective. This thesis contributes to the understanding of cold ironing as a viable solution for improving port sustainability, optimizing its adoption and maximizing its environmental and economic benefits.