Humankind uses energy at a rate of 18 TW. How much energy does this equate to in terms of yearly usage?

To find the yearly energy usage for humankind at a rate of 18 terawatts (TW), it’s necessary to convert the power measurement into an energy measurement over time. Power (measured in watts) is a measure of energy per unit time. To calculate total energy, you can multiply power by the time period over which the power is used.

1 terawatt is equal to 1 trillion watts, or (1 \times 10^{12}) watts. Therefore, 18 TW translates to:

[ 18 , \text{TW} = 18 \times 10^{12} , \text{W} ]

To find the annual energy usage, this power must be multiplied by the number of seconds in a year. There are 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, and approximately 365.25 days in a year (accounting for leap years):

[ 1 , \text{year} = 60 , \text{s/min} \times 60 , \text{min/hr} \times 24 , \text{hr/day} \times 365.25 , \text{