What are the cost benefits of regular gasoline versus Hydrogen fuel cells?

The research questions are: 1. What are the cost benefits of regular gasoline versus Hydrogen fuel cells? 2. What are the precautions needed to safely store hydrogen in a vehicle? 3. What is the environmental impact of using hydrogen as a transportation fuel? 4. What are the barriers to developing hydrogen fuel cell cars? already done a part of it. all sources provided has to be written in the best academic way possible