Calculate the energy cost (kWh/p/d)

Question

Australia produces 20 megatonnes (Mt) of alumina every year, where each tonne requires 3.8 MWh of heat energy to produce. Calculate the energy cost (kWh/p/d) to produce alumina spread across the population of Australia, equal to 23 million people.

Answer 1

first, we convert 2OMt per year to 20,000,000 tonnes per year

second, we convert 3.8MWh to 38,000kWh per tonne

third, we multiply 20,000,000 by 38,000 = 760,000,000,000

third, we divide by 365 days = 2,000,000,000

fourth, we divide by the number of persons 23,000,000 = 2.3 x 10⁷

 

the result is 2 x 10⁹/2.3 x 10⁷ = 0.9 x 10² = 90