Hydrogen H2 has the smallest mass of all molecules. Therefore, hydrogen fuel is a profitable fuel for transport so far as it carries more energy per unit mass.
Green hydrogen: clean fuel is coming out on the highway
![](https://kc.pnu.edu.ua/wp-content/uploads/sites/11/2021/02/hydroflex1.jpg)
Hydrogen H2 has the smallest mass of all molecules. Therefore, hydrogen fuel is a profitable fuel for transport so far as it carries more energy per unit mass.