0
$\begingroup$

The world consumes energy at the rate of about $466 EJ$ per year, where the joule$(J)$ is the SI energy unit.
Convert this figure to watts$(W)$ , where $W= 1 J/s$, and then estimate the average per capita energy consumption rate in watts.

I'm having trouble understanding this problem. Can someone please explain me in detail the way to solve this problem. First of all I do not know what the unit $EJ$ represents, is it $exajoule$?

$\endgroup$

2 Answers 2

1
$\begingroup$

Seems that $\text{EJ}$ refers to exajoule, which is ${10}^{18}$ joules, according to Wikipedia...so we have

$$466 \;\text{EJ} = (466 \times {10}^{18}) \;\text{J/yr}$$ and this converts to $$\frac{(466 \times {10}^{18}) \;\text{J}} {1 \;\text{yr}} = \frac{(466 \times {10}^{18}) } {1 \times 365 \times 24 \times 60 \times 60}\; \text{W}$$ because 1 year has 365 days, 1 day has 24 hours, 1 hour has 60 minutes and 1 minute has 60 seconds. Do the division and you'll get ${1.47} \times {10}^{13} \;\text{W}$ for the world population.

The question asked for per-capita consumption. Hence, I'd assume the population is now 7 billion or $7 \times {10}^{9}$. So continuing the calculation, we have

$$\frac{{1.47} \times {10}^{13} \text{W}} {7 \times {10}^{9} \text{people} } = 2100 \text { W / person}$$

$\endgroup$
1
  • $\begingroup$ All the rest is estimating the world population and dividing the result by that number. $\endgroup$ Feb 2, 2013 at 8:55
0
$\begingroup$

2100 w / person. If my neighbour eats two apples per day and i do not; that makes one apple per day each. Now we should kwow what the consumption is in the USA per-capita and then in Tanzania per-capita or in most of African countries where so many people do not still have electricity.

$\endgroup$
1
  • $\begingroup$ The romantic notion that there are "African" from that "country" of Africa (let alone GASP! the continent!) is besides highly offensive, also utterly flawed,(Perhaps based an a 19th century image of "Africa!"? Which was just as flawed to begin with. (Compare: the worlds idea that every American has guns and shoots them all day long. Most people are shocked to discover only about a 3rd of them even has guns) Pretty much every one in the world has access to, or is a consumer of electricity, if only because everyone rides a bus and/or has a cellphone.Now, running water..... $\endgroup$ Mar 16, 2019 at 12:24

Not the answer you're looking for? Browse other questions tagged .