4 ms·

Plenty of reasons to want this to work. Ground-based solar has so many flaws - ecological, legal, social, even efficiency is poor. And we aren't making any more

Plenty of reasons to want this to work. Ground-based solar has so many flaws - ecological, legal, social, even efficiency is poor. And we aren't making any more open ground near cities to put square miles of solar farms. Space-based is becoming more attractive every year. Lift costs, panel weight and cost, computing power are all going in the right direction to improve the space-solar economic equation. As for space, a few square miles is trivial to find a place for. Further, the usual bugaboos about "How do you get it down here?!" (microwaves to high-capacity receivers) can be circumvented entirely if you use the power in space e.g. in AI-training compute centers also in orbit.

akira2501 2y ago
> even efficiency is poor. Not really. The atmosphere does reduce solar energy at the surface, but the fact we're 1 AU from the sun is the major reason we receive so little power. The costs of putting things into orbit and maintaining things in orbit are unlikely to ever overcome the atmospheric difference. Plus, on the surface of the Earth, you get convective cooling in atmosphere "for free." Good luck keeping your panels cool on orbit.
bloedsinnig 2y ago
Ground based solar has very little flaws. Its cheap (its just silicium plates), we will have organic based systems in the future. You will be able to print it in the future. Efficency is huge. We have so much unused roof space, its ridicoulous. parking spots, house roofs, commercial building roofs. Why would you think its smart to send computers, which need cooling, up to use the energy over there? Do you know how hard it is to radiate heat away in space?
- scotty79 2y ago
  > commercial building roofs. And southern walls.
  - geraldcombs 2y ago
    And canals: https://www.tid.org/current-projects/project-nexus/ https://www.tid.org/current-projects/project-nexus/
- deleted 2y ago
  [deleted]
- euroderf 2y ago
  Space-based will by necessity be centralised. Some businesspeople like that kind of thing.
- JoeAltmaier 2y ago
  All the usual 'obvious' points; all wrong. Rooftop solar is pointless. Roofs don't scale; roofs are not optimally placed; roofs are hard to reach; roofs are not engineered to support the load or hardware. Open cheap unobstructed ground near a grid with clear access are optimal. Roofs are exactly zero of those. Efficincy is 50% at best - the daily occurrence of the terrestrial eclipse known as 'night'? Remember? Any panel argument is the same in space. Don't know what that point was about. Using energy near the generation point is optimal. The heat argument is good; it goes double for a planet that's already heating up and causing problems. Get that shit away from our ecosystems. Any advantage of ground-based solar is eroding daily with advances in lift cost, land price rises, congestion in cities. It's only a matter of time and money.
dekhn 2y ago
We don't need open ground near cities to put square miles of solar farms. Why would you do that? We have long-distance transmission lines. https://en.wikipedia.org/wiki/Pacific_DC_Intertie https://en.wikipedia.org/wiki/Pacific_DC_Intertie is 3GW from The Dalles Oregon to Los Angeles (as well as other parts of the west). Putting AI training in space is daft. Heat dissipation is the problem (on top of gravity)
mbreese 2y ago
> can be circumvented entirely if you use the power in space e.g. in AI-training compute centers also in orbit. In addition to power requirements and data transfer, I always thought that the main logistical issue with in-orbit computers was heat dissipation. If you have a need for compute in orbit (let’s assume this is true), you’d still need a way to dissipate heat. But this isn’t something that can happen easily in space. (But it makes me wonder if you could have a Peltier generator attached to a hot chip to remove heat and “recycle” some of that energy back into electricity… not that it would help too much with the other issue with compute in orbit - data transfer)
- schmidtleonard 2y ago
  Peltier gives you energy in exchange for making heat transfer worse. Or you can make heat transfer better by paying a bit of energy. The exchange rate is very poor in both directions.
  - mbreese 2y ago
    I know they are very inefficient, but are they more inefficient at heat transfer than the alternative of radiant cooling? I have no idea. I know they are used for electricity generation on some other spacecraft, but I always thought it was because it was a method of last resort. But I had never considered if a Peltier would work for cooling.
    - schmidtleonard 2y ago
      Peltiers are never an alternative to radiant cooling. They do not get rid of heat, they pump it from one side to another (if you apply power) or resist its flow (if you extract power -- this is what RTGs do). You still have to get rid of the heat when it reaches the other side of the Peltier.
- brianbreslin 2y ago
  forgive my ignorance on this q. I always assumed based on movies that the temperatures in space were very cold (like near absolute zero). So wouldn't putting a hot data center in space just dissipate heat? Do shuttles and space stations not radiate heat?
JoeAltmaier 2y ago
...and today somebody posts a WSJ article on exactly this subject.

akira2501 2y ago

> even efficiency is poor. Not really. The atmosphere does reduce solar energy at the surface, but the fact we're 1 AU from the sun is the major reason we receive so little power. The costs of putting things into orbit and maintaining things in orbit are unlikely to ever overcome the atmospheric difference. Plus, on the surface of the Earth, you get convective cooling in atmosphere "for free." Good luck keeping your panels cool on orbit.

bloedsinnig 2y ago

Ground based solar has very little flaws. Its cheap (its just silicium plates), we will have organic based systems in the future. You will be able to print it in the future. Efficency is huge. We have so much unused roof space, its ridicoulous. parking spots, house roofs, commercial building roofs. Why would you think its smart to send computers, which need cooling, up to use the energy over there? Do you know how hard it is to radiate heat away in space?

scotty79 2y ago
> commercial building roofs. And southern walls.
- geraldcombs 2y ago
  And canals: https://www.tid.org/current-projects/project-nexus/ https://www.tid.org/current-projects/project-nexus/
deleted 2y ago
[deleted]
euroderf 2y ago
Space-based will by necessity be centralised. Some businesspeople like that kind of thing.
JoeAltmaier 2y ago
All the usual 'obvious' points; all wrong. Rooftop solar is pointless. Roofs don't scale; roofs are not optimally placed; roofs are hard to reach; roofs are not engineered to support the load or hardware. Open cheap unobstructed ground near a grid with clear access are optimal. Roofs are exactly zero of those. Efficincy is 50% at best - the daily occurrence of the terrestrial eclipse known as 'night'? Remember? Any panel argument is the same in space. Don't know what that point was about. Using energy near the generation point is optimal. The heat argument is good; it goes double for a planet that's already heating up and causing problems. Get that shit away from our ecosystems. Any advantage of ground-based solar is eroding daily with advances in lift cost, land price rises, congestion in cities. It's only a matter of time and money.

dekhn 2y ago

We don't need open ground near cities to put square miles of solar farms. Why would you do that? We have long-distance transmission lines. https://en.wikipedia.org/wiki/Pacific_DC_Intertie https://en.wikipedia.org/wiki/Pacific_DC_Intertie is 3GW from The Dalles Oregon to Los Angeles (as well as other parts of the west). Putting AI training in space is daft. Heat dissipation is the problem (on top of gravity)

mbreese 2y ago

> can be circumvented entirely if you use the power in space e.g. in AI-training compute centers also in orbit. In addition to power requirements and data transfer, I always thought that the main logistical issue with in-orbit computers was heat dissipation. If you have a need for compute in orbit (let’s assume this is true), you’d still need a way to dissipate heat. But this isn’t something that can happen easily in space. (But it makes me wonder if you could have a Peltier generator attached to a hot chip to remove heat and “recycle” some of that energy back into electricity… not that it would help too much with the other issue with compute in orbit - data transfer)

schmidtleonard 2y ago
Peltier gives you energy in exchange for making heat transfer worse. Or you can make heat transfer better by paying a bit of energy. The exchange rate is very poor in both directions.
- mbreese 2y ago
  I know they are very inefficient, but are they more inefficient at heat transfer than the alternative of radiant cooling? I have no idea. I know they are used for electricity generation on some other spacecraft, but I always thought it was because it was a method of last resort. But I had never considered if a Peltier would work for cooling.
  - schmidtleonard 2y ago
    Peltiers are never an alternative to radiant cooling. They do not get rid of heat, they pump it from one side to another (if you apply power) or resist its flow (if you extract power -- this is what RTGs do). You still have to get rid of the heat when it reaches the other side of the Peltier.
brianbreslin 2y ago
forgive my ignorance on this q. I always assumed based on movies that the temperatures in space were very cold (like near absolute zero). So wouldn't putting a hot data center in space just dissipate heat? Do shuttles and space stations not radiate heat?

JoeAltmaier 2y ago

...and today somebody posts a WSJ article on exactly this subject.