Dihydrogen releases large quantities of heat on combustion.
Pollutants in combustion of dihydrogen will be less than petrol. The only pollutant will be the oxide of dinitrogen which is present as an impurity. Thus hydrogen economy is an alternative the bane principle is the transportation and storage of energy in the form of liquid or gaseous dihydrogen. Advantage is that energy is transmitted in the form of dihydrogen and not as electric power.