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On Mars the r^2 scaling just means that solar panels produce ~half as much energy as on Earth. For dust there are electrostatic sweeping grids that automaticall

On Mars the r^2 scaling just means that solar panels produce ~half as much energy as on Earth. For dust there are electrostatic sweeping grids that automatically remove it. Realize that nuclear also gets more expensive on Mars, because there are no convenient lakes or rivers for cooling water. Instead you need to build a large radiator or underground pipe grid.

verzali 2y ago
About 43% of the energy. But its also worse than that because Mars has a more eccentric orbit and slightly bigger axial tilt. Seasonal variations in solar energy are thus much larger than on Earth (at perihelion you get around 700W/m2, at aphelion about 500W/m2). Also seasons are longer on Mars and the planet moves more slowly around perihelion, so that it spends more time further from the Sun. You also get global dust storms enveloping the planet every few years for several weeks at a time. These leave a lot of dust on panels, but they also drastically cut the solar radiation received at the surface. Solar panels degrade faster on Mars too. You could replace them by sending new ones, but that will add up to a lot of mass. Or you could design panels that degrade more slowly, but that's not a given yet. Basically solar is not going to scale well on Mars. It might work for a small facility, but not for a city.
- dexwiz 2y ago
  If you had a city, could you produce them locally then?
  - tirant 2y ago
    Yes, but you then need to have an already developed full supply chain, and for that you need to bootstrap your energy production first hand. My personal hope is that there might be some untapped resources of hydrocarbons or methane in Mars that could be used to generate energy from local sources.
    - philipkglass 2y ago
      Local hydrocarbons could help for making materials/chemicals but they wouldn't help for energy. Mars doesn't have free oxygen in the atmosphere so there's nothing to burn them with.
- schiffern 2y ago
  If you choose your latitude right (roughly 10-30 degrees North), the variability caused by eccentricity and axial tilt mostly cancels out. https://images.squarespace-cdn.com/content/v1/61b40f74f9cdfc6480dec5f1/593b84b0-a720-4c12-ad82-04ec0be555b4/mars+solar+irradiation+at+the+top+of+the+atmopshere.png https://images.squarespace-cdn.com/content/v1/61b40f74f9cdfc... As for dust storms, you need stored energy anyway -- nuclear power goes down too! A big tank of oxygen counts as "stored energy," and so does a big container of desorbed lithium carbonate (CO2 scrubber material).
- etiennebausson 2y ago
  I expect solar infrastructure for Mars would be done in orbit and beamed down. On earth, they are produced on the ground and putting them in orbit cost way too much. If the panels are send from Earth to Mars, then dropping them in orbit mean that you don't have to account for their weight for landing... or don't have to land at all. Park in orbit, drop you payload and back to earth for the next delivery.
  - lutusp 2y ago
    > I expect solar infrastructure for Mars would be done in orbit and beamed down. Remember that Mars' atmospheric pressure is a tiny fraction of that on Earth, so the performance difference between a solar panel in orbit, and on the surface, is negligible (until a dust storm starts). So there's no reason to consider putting them in orbit, especially considering the much higher complexity and power losses involved in delivering power to the surface.
    - inglor_cz 2y ago
      "the performance difference between a solar panel in orbit, and on the surface, is negligible (until a dust storm starts). So there's no reason to consider putting them in orbit, especially considering the much higher complexity and power losses involved in delivering power to the surface." I wonder if you could build a space elevator on Mars (third of our gravity = much less demanding on materials) and then simply get the electricity generated by orbital solar panels back to the surface using ye olde cables, immune to dust storms.
    - etiennebausson 2y ago
      The point of doing it in orbit isn't the increased performance, it's the reduced maintenance, and reduced transportation cost. Every drop of fuel used to land and take-off has to be send to earth orbit first. If you replace that fuel with payload, you're looking at a very different equation.
  - Yizahi 2y ago
    Casey has an article why beaming energy from space to ground is not worth it, due to many compounding issues. Mars can probably only strike off one issue, about beam density and ramp it up, but has many more unique issues - far away to control and replace, less energy density per area, and other issues with small colony size. https://caseyhandmer.wordpress.com/2019/08/20/space-based-solar-power-is-not-a-thing/ https://caseyhandmer.wordpress.com/2019/08/20/space-based-so...
- childintime 2y ago
  > Basically solar is not going to scale well on Mars. With 500W in every season, no clouds, things compare well to where I live. Should give close to 1000kWh/year, but reliably so.
oneshtein 2y ago
Mars is very cold, so all this waste heat from nuclear reactor can be used to heat spaces, but nuclear reactors needs enriched fuel to work, which is dangerous to transport. If Petrovskite Solar Cells will work on Mars reliably, they can be produced directly on Mars and used together with sand batteries for stable supply of energy and heat.
ninalanyon 2y ago
Surely most of the waste would be needed for space heating and process heat?

verzali 2y ago

About 43% of the energy. But its also worse than that because Mars has a more eccentric orbit and slightly bigger axial tilt. Seasonal variations in solar energy are thus much larger than on Earth (at perihelion you get around 700W/m2, at aphelion about 500W/m2). Also seasons are longer on Mars and the planet moves more slowly around perihelion, so that it spends more time further from the Sun. You also get global dust storms enveloping the planet every few years for several weeks at a time. These leave a lot of dust on panels, but they also drastically cut the solar radiation received at the surface. Solar panels degrade faster on Mars too. You could replace them by sending new ones, but that will add up to a lot of mass. Or you could design panels that degrade more slowly, but that's not a given yet. Basically solar is not going to scale well on Mars. It might work for a small facility, but not for a city.

dexwiz 2y ago
If you had a city, could you produce them locally then?
- tirant 2y ago
  Yes, but you then need to have an already developed full supply chain, and for that you need to bootstrap your energy production first hand. My personal hope is that there might be some untapped resources of hydrocarbons or methane in Mars that could be used to generate energy from local sources.
  - philipkglass 2y ago
    Local hydrocarbons could help for making materials/chemicals but they wouldn't help for energy. Mars doesn't have free oxygen in the atmosphere so there's nothing to burn them with.
schiffern 2y ago
If you choose your latitude right (roughly 10-30 degrees North), the variability caused by eccentricity and axial tilt mostly cancels out. https://images.squarespace-cdn.com/content/v1/61b40f74f9cdfc6480dec5f1/593b84b0-a720-4c12-ad82-04ec0be555b4/mars+solar+irradiation+at+the+top+of+the+atmopshere.png https://images.squarespace-cdn.com/content/v1/61b40f74f9cdfc... As for dust storms, you need stored energy anyway -- nuclear power goes down too! A big tank of oxygen counts as "stored energy," and so does a big container of desorbed lithium carbonate (CO2 scrubber material).
etiennebausson 2y ago
I expect solar infrastructure for Mars would be done in orbit and beamed down. On earth, they are produced on the ground and putting them in orbit cost way too much. If the panels are send from Earth to Mars, then dropping them in orbit mean that you don't have to account for their weight for landing... or don't have to land at all. Park in orbit, drop you payload and back to earth for the next delivery.
- lutusp 2y ago
  > I expect solar infrastructure for Mars would be done in orbit and beamed down. Remember that Mars' atmospheric pressure is a tiny fraction of that on Earth, so the performance difference between a solar panel in orbit, and on the surface, is negligible (until a dust storm starts). So there's no reason to consider putting them in orbit, especially considering the much higher complexity and power losses involved in delivering power to the surface.
  - inglor_cz 2y ago
    "the performance difference between a solar panel in orbit, and on the surface, is negligible (until a dust storm starts). So there's no reason to consider putting them in orbit, especially considering the much higher complexity and power losses involved in delivering power to the surface." I wonder if you could build a space elevator on Mars (third of our gravity = much less demanding on materials) and then simply get the electricity generated by orbital solar panels back to the surface using ye olde cables, immune to dust storms.
  - etiennebausson 2y ago
    The point of doing it in orbit isn't the increased performance, it's the reduced maintenance, and reduced transportation cost. Every drop of fuel used to land and take-off has to be send to earth orbit first. If you replace that fuel with payload, you're looking at a very different equation.
- Yizahi 2y ago
  Casey has an article why beaming energy from space to ground is not worth it, due to many compounding issues. Mars can probably only strike off one issue, about beam density and ramp it up, but has many more unique issues - far away to control and replace, less energy density per area, and other issues with small colony size. https://caseyhandmer.wordpress.com/2019/08/20/space-based-solar-power-is-not-a-thing/ https://caseyhandmer.wordpress.com/2019/08/20/space-based-so...
childintime 2y ago
> Basically solar is not going to scale well on Mars. With 500W in every season, no clouds, things compare well to where I live. Should give close to 1000kWh/year, but reliably so.

oneshtein 2y ago

Mars is very cold, so all this waste heat from nuclear reactor can be used to heat spaces, but nuclear reactors needs enriched fuel to work, which is dangerous to transport. If Petrovskite Solar Cells will work on Mars reliably, they can be produced directly on Mars and used together with sand batteries for stable supply of energy and heat.

ninalanyon 2y ago

Surely most of the waste would be needed for space heating and process heat?