According to MIT's study, the solar resource is the largest energy source available on earth. Roughly 174,000 terawatts (TW) of power are continually delivered by solar radiation to the upper level of the earth’s atmosphere. Given that global average power consumption totals roughly 17 TW, the solar energy that strikes the earth in one hour is more than enough to supply all of humanity’s current energy needs for one year. The above publication can be downloaded from here.
Americans use 26 percent of the world’s power despite making up less than 5 percent of the world’s population. (Source)