This book explores the potential of ammonia (NH₃) as a next-generation fuel for achieving Net Zero emissions in the transport and power sectors. With increasing regulatory pressure to reduce carbon dioxide (CO₂) and carbon monoxide (CO) emissions, industries are seeking non-carbonaceous energy sources. Ammonia, with its carbon-free molecular structure, offers a promising alternative, but challenges such as high auto-ignition temperature, slow chemical kinetics, and combustion efficiency must be addressed. This book presents state-of-the-art research on ammonia-fueled internal combustion engines (ICEs), emission characteristics, and combustion enhancement techniques. It covers critical risk factors for ammonia-fueled marine diesel engines, safety considerations, pre-chamber ignition for lean combustion, and advanced optical techniques for soot characterization in fuel spray flames. By providing insights into cutting-edge developments, this book serves as a valuable resource for researchers, engineers, and industry professionals working toward sustainable and low-carbon combustion technologies.