In the section of this chapter about transportation of fossi

In the section of this chapter about transportation of fossil fuels, I pointed out that humankind uses about 500 EJ of energy each year, nearly all of them fossil fuels, and that energy content of fossil fuels is around 30 to 60 MJ/kg. (a) Using an approximate figure of 40 MJ/kg, estimate the total mass of fossil fuels we burn each year. (b) Assume that each kilogram of fuel has to be moved 1,000 km from its source to where it’s burned (more for imported oil, less for some coal), at an average speed of 20km per hour. Estimate the total mass of fuel that must be in transit at a given time.

Solution

We are given that

humankind uses about 500 EJ of energy each year

(a)

In 1 year humankind uses = 500 EJ=500000000000000 MJ energy

40MJ energy content of fossil fuel = 1 Kg mass

so,

1MJ energy content of fossil fuel = (1/40) Kg mass

500000000000000 MJ energy content of fossil fuel = (1/40)*500000000000000 Kg mass

total fossil fuels burns =12500000000000 Kg per year.........Answer

(b)

since, the distance , it has to moved =1000km

and average speed =20k/hr

now, we can find time it will take

time = distance / speed

time = 1000/20

time =50 hours

now, we will convert hours into years

1 hours = 0.000114155 year

so, 50 hours =50*0.000114155 year

time =0.00570776 years

now, we can find total mass

total mass = (mass per year) *time

total mass=(12500000000000 Kg per year)*0.00570776 year

total mass =71347000000 Kg.............Answer