Sun could be termed as ultimate source if energy as it directly and indirectly all the sources of energy like following :-

1. it provides solar energy
2. it creates wind energy by the process of unequal heating of earth' s surface provides heat which indirectly helps to create fossil fuels which we use to create electricity
4. it helps in water cycle which involves evaporation and precipitation through which water gets collected in dams and it produces hydroelectricity