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Space solar is now something of a fossil idea from the 70s. At the time it was thought that solar panels would be comparatively expensive, and spacelaunch/space

Space solar is now something of a fossil idea from the 70s. At the time it was thought that solar panels would be comparatively expensive, and spacelaunch/space manufacturing would be comparatively cheap. But the economics changed out from under its feet: solar panels became a hundred times cheaper http://costofsolar.com/management/uploads/2013/06/price-of-solar-power-drop-graph.jpg http://costofsolar.com/management/uploads/2013/06/price-of-s... but space stuff remained the same price. Now the most economical option is to put solar arrays on the Earth's surface, but build ten times more of them than you need. Specifically, one of the killer engineering problems of space based solar is getting the power back to Earth. Tom Murphy wrote the canonical post on this: https://dothemath.ucsd.edu/2012/03/space-based-solar-power/ https://dothemath.ucsd.edu/2012/03/space-based-solar-power/ Depending on what frequency you're using and how big the orbital antenna is, the receiving rectenna array is going to be a couple kilometers across. If you use a beam power density that isn't going to cook birds flying across the antenna, then you're not receiving too much more power than regular solar irradiation. The atmosphere eats some of the power, the receiving antenna eats some power, and then the rectified power has to be converted to AC, losing a few percent more power. Maybe 50% total transmission loss. For the cost of putting a million tons into orbit, you might want to just build more ground solar.

pfdietz 5y ago
Space solar was an idea from when PV was expensive. Put those expensive PV up in space with cheap launchers so they're more effective, that was the idea. But now PV is very cheap, so there's no need to put it in 24/7 sunlight. And with storage improving transmitting the power in time will be cheaper than transmitting it in space.
SubiculumCode 5y ago
Yes, this IS the problem. Could not a space tether system help with that? Although, space elevators are quite a daunting challenge too.
goodpoint 5y ago
Besides, there is no need for space solar. The amount of solar radiation hitting deserts around the planet is way more than enough to generate electricity for the whole human society.
- orthecreedence 5y ago
  And soon we'll all live in a desert, so it will finally make sense to generate our power with solar.
tuatoru 5y ago
Its advantage is continuity of supply - ground based PV in a single location is only available for about a third of a day. Building transcontinental and transoceanic UHV power transmission lines circling the northern hemisphere, providing the same function is probably cheaper, but may be more politically difficult. But that's moot. We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so.
- roughly 5y ago
  > We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so. Do you have more info on this? I’m skeptical of any claims of scaling to global scale that quickly.
  - tuatoru 5y ago
    Form Energy's iron-air battery, for instance - good at the two days to two weeks duration, needed as backup for wind during prolonged calms. We already mine a great deal of iron; the extra needed globally wouldn't really be noticed. Others are working on iron-air also. At least a couple of teams are quite far along with hot rock energy storage. Good for the one week to one month timescale. Various other battery technologies for sub-day timescales - lithium for grid frequency stabilisation, flow batteries. I don't know of any active trials of ammonia energy storage, one of the most scalable candidates for seasonal storage, but ammonia engineering is very old and very widespread, so there don't appear to be roadblocks to scaling up rapidly once required. The YouTube channels "Just Have a Think"[1] and "Undecided with Matt Ferrell"[2] focus on this stuff, and do some research. Edit: you should be sceptical; well done! Scaling really does take forever. That's why the only viable technologies are those already lying around all over the place, being used for other things. 1. https://www.youtube.com/c/JustHaveaThink/videos https://www.youtube.com/c/JustHaveaThink/videos 2. https://www.youtube.com/c/UndecidedMF/videos https://www.youtube.com/c/UndecidedMF/videos
    - pfdietz 5y ago

pfdietz 5y ago

Space solar was an idea from when PV was expensive. Put those expensive PV up in space with cheap launchers so they're more effective, that was the idea. But now PV is very cheap, so there's no need to put it in 24/7 sunlight. And with storage improving transmitting the power in time will be cheaper than transmitting it in space.

SubiculumCode 5y ago

Yes, this IS the problem. Could not a space tether system help with that? Although, space elevators are quite a daunting challenge too.

goodpoint 5y ago

Besides, there is no need for space solar. The amount of solar radiation hitting deserts around the planet is way more than enough to generate electricity for the whole human society.

orthecreedence 5y ago
And soon we'll all live in a desert, so it will finally make sense to generate our power with solar.

tuatoru 5y ago

Its advantage is continuity of supply - ground based PV in a single location is only available for about a third of a day. Building transcontinental and transoceanic UHV power transmission lines circling the northern hemisphere, providing the same function is probably cheaper, but may be more politically difficult. But that's moot. We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so.

roughly 5y ago
> We have a cornucopia of viable storage methods in active development--viable meaning capable of being scaled up to global scale in 20 years or so. Do you have more info on this? I’m skeptical of any claims of scaling to global scale that quickly.
- tuatoru 5y ago
  Form Energy's iron-air battery, for instance - good at the two days to two weeks duration, needed as backup for wind during prolonged calms. We already mine a great deal of iron; the extra needed globally wouldn't really be noticed. Others are working on iron-air also. At least a couple of teams are quite far along with hot rock energy storage. Good for the one week to one month timescale. Various other battery technologies for sub-day timescales - lithium for grid frequency stabilisation, flow batteries. I don't know of any active trials of ammonia energy storage, one of the most scalable candidates for seasonal storage, but ammonia engineering is very old and very widespread, so there don't appear to be roadblocks to scaling up rapidly once required. The YouTube channels "Just Have a Think"[1] and "Undecided with Matt Ferrell"[2] focus on this stuff, and do some research. Edit: you should be sceptical; well done! Scaling really does take forever. That's why the only viable technologies are those already lying around all over the place, being used for other things. 1. https://www.youtube.com/c/JustHaveaThink/videos https://www.youtube.com/c/JustHaveaThink/videos 2. https://www.youtube.com/c/UndecidedMF/videos https://www.youtube.com/c/UndecidedMF/videos
  - pfdietz 5y ago