Off-world Power Generation: Difference between revisions

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* Approximate energy absorbable by a solar panel in space: 320W / 1.64m^2 / .48% = 400W/m^2 in space
* Approximate energy absorbable by a solar panel in space: 320W / 1.64m^2 / .48% = 400W/m^2 in space
* Approximate required size of a solar array "near Earth" (including l1) to power NYC: 100GW / 400W/m^s = 250 sq km
* Approximate required size of a solar array "near Earth" (including l1) to power NYC: 100GW / 400W/m^s = 250 sq km
* Dan: 1 out of every 811 humans on earth live in NYC, so 250 sq km dish * 811 (assuming every human uses as much energy as a New Yorker) requires a solar array of only around 200,000 sq km - the size of Nebraska - to power the globe.

Revision as of 01:19, 29 October 2018

Given:

  • earth to moon: 238,900 miles
  • there are four lagrange points that provide constant sun exposure at predictable locations
  • l1 to earth/moon: 1 million miles
  • the sun primarily produces visible light (not microwaves or gamma...)
  • laser transmission is more efficient than microwave, except where earth's atmosphere interferes
  • current status: A Gigawatt-range microwave system would weigh ~80,000 tons (prohibitively expensive) more lots more
  • Solar cell efficiency

Premises:

<Earth> <-microwave-- <Earth-orbit satellite> <-laser-- <Earth's moon> <-laser-- <L1 solar array>
<Earth> <-clearsky-burst-laser-- <Earth's moon> <-laser-- <L1 solar array>
<Earth> <-clearsky-burst-laser-- <L1 solar array>
  • <Earth> <- <Earth-orbit satellite>

Laser transmit antenna in space: 1 meter diameter per GW Receive: Several hundred meters across

  • <Earth-orbit satellite> <- <Earth's moon>
  • <Earth's moon> <- <Earth-Sol Lagrange-point solar array>

Targeting the energy requirement of NYC:

  • Power is measured in Newton-meters per second or Joules per second or Watts.
  • ~3000 trillion BTU in 2016 = 3000 trillion btu / 365 days = 3.4E+11 btu/hr = 1.0036680479e+11 watts = 100 GW

PV energy collection

  • PV power stations collect more power than solar thermal power stations. They seem to average ~3 MW/km^2 (throwing out 2 ridiculous outliers).
  • Traditional single-junction cells have a maximum theoretical efficiency of 33.16% more. In reality it is around 18.7%.
  • A 65"x39" (1.64 m^2) solar panel made in 2018 produces ~320W.
  • About 48% of solar energy hitting the Earth reaches the surface. Perhaps optimistic, but we will divide by .48 to get energy-in-space vs on-earth.
  • Approximate energy absorbable by a solar panel in space: 320W / 1.64m^2 / .48% = 400W/m^2 in space
  • Approximate required size of a solar array "near Earth" (including l1) to power NYC: 100GW / 400W/m^s = 250 sq km
  • Dan: 1 out of every 811 humans on earth live in NYC, so 250 sq km dish * 811 (assuming every human uses as much energy as a New Yorker) requires a solar array of only around 200,000 sq km - the size of Nebraska - to power the globe.