Recent research in the UK reveals the promising potential of hydrogen combustion engines in reducing harmful emissions from diesel trains, aligning with the country's ambitious goal to phase out diesel trains by 2040. The study focuses on technical, economic, and environmental analyses of converting diesel trains to hydrogen power. Results show that hydrogen combustion engines can significantly decrease carbon emissions while maintaining similar levels of nitrogen oxides emissions as traditional diesel engines. Green hydrogen is highlighted as a key solution that could lead to a substantial reduction in CO2-equivalent emissions over the operational life of trains. The research also stresses the economic feasibility of hydrogen conversion compared to extensive electrification efforts, with conversion costs estimated at approximately £200,000 per train car. However, challenges related to NOx emissions from hydrogen combustion engines require further exploration of advanced emissions control technologies. The study underscores the importance of coordinated efforts and policies to support the transition to hydrogen-powered trains, emphasizing the need for infrastructure development such as hydrogen storage and refueling stations. Overall, the research advances discussions on sustainable transport solutions, positioning hydrogen as a feasible, cost-effective, and environmentally friendly option for the future of rail transport.