Answer:
t=17.61 years.
Step-by-step explanation:
Given that
Reserve of energy = 10,000 EJ
Energy used by human = 18 TW
We know that


So



Lets t time after energy will be exhaust
So



We know that
1 year = 365 days
1 year = 365 x 24 hr
1 year = 365 x 24 x 3600 s

So

t=17.61 years.