(September 11, 2021 at 12:25 pm)Jehanne Wrote:(September 11, 2021 at 12:16 pm)polymath257 Wrote: It's wrong. Energy usage of the US is about 93 quadrillion BTUs a year, which amounts to just less than 10^20 Joules per year. The solar constant is 1.361*10^3 Joules per square meter per second. That gives about 4*10^10 Joules per square meter per year. Dividing the two, we see that (capturing *every* photon) would take about 2.5*10^9 square meters, which is a square that is 50 kilometers on a side.
Now, efficiency and hours of daylight increase this, but it is still a long way from the total area of the US.
We use a trillion watts on average, right?
(September 11, 2021 at 12:25 pm)polymath257 Wrote: Nope. that is in square *meters*, not square kilometers. So, a 50km by 50km area would do it.
Yep, I messed up.
And, so, a 50 km by 50 km array is completely doable!
Because of efficiency and the fact that the sun isn't always up (so we don't get the full solar constant all the time), it would be more than that. But it is still a LOT less than the total area of even one medium sized state.
