How long does it take the Sun to deliver to earth the total amount of energy humankind uses in a year?

Answer 1

First Lets find out what is the global energy consumption of Humans:

According to the plot on https://en.wikipedia.org/wiki/World_energy_consumption

I assume 160000TWh or 1.6* 10¹⁷Wh

the Solar constant . the intensity of solar radiation above atmosphere is about 1360 W/m²

that is 1360 J per second for each square meter area perpendicular to the sun incoming radiation. if you multiply it by earth cross section (π R_⊕²) .

the total energy earth receives in one hour is 1360 W/m² * 3.14 * (6.4*10⁶)² m² * 1hr = 1.75 * 10¹⁷ Wh

So it took sun less than an hour to provide enough energy for humans to consume in a year. (here 54min and 51.43s)

Note1: W is a unit of power Wh is a unit of energy .

A 10w light bulb uses 10Wh(= 10 J/s * 3600s =3.6*10⁴ J) energy in an hour

Note2: the solar constant (F=L_sun/4π d² , where d=1AU) is giving the total energy recieved by 1meter square of horizontal ground when the sun is on the zenith though sun at each moment illuminaes half of the earth surface (2πR_⊕²) it is not perpendicular to all of its surface but it is to the earth cross section.