Water contains hydrogen son, the fuel of the universe.

The most plentiful element and LEGO of the spheres, or as Zappa reasons:

 “Some scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that is the basic building block of the universe.” 

 ― Frank Zappa


Hydrogen has an energy density of approximately 120 MJ/kg, almost three times more than diesel or gasoline. In electrical terms, the energy density of hydrogen is equal to 33.6 kWh of usable energy per kg, versus diesel which only holds about 12–14 kWh per kg.
https://rmi.org/run-on-less-with-hydrogen-fuel-cells/