5 ms·

What’s the bullish story for why solar panels in space with microwave beaming is better than solar panels on earth?

by vlovich123 3y ago

simonebrunozzi 3y ago
There isn't. It's just another excuse to justify spending lots of money on things that make no sense.
temp0826 3y ago
Haven't you played SimCity 2000?
doctoboggan 3y ago
I haven’t done the math or really thought about it all that much but one reason could be that space has a lot of, well, space. You can build a huge array without wasting land that could be used for something else, condense the power down to a beam and send it to earth.
JumpCrisscross 3y ago
> What’s the bullish story for why solar panels in space with microwave beaming is better than solar panels on earth? Space-based solar power (SBSP) has three advantages over terrestrial solar: flexibility, footprint and theoretical efficiency. The classic case for flexibility is disaster zones; it's easier to set up receiving meshes than build new power plants. The problem is humanitarian crises don't pay. The real sell is military and mining. Beaming power to remote operations simplifies logistics. Footprint is minor, but worth mentioning: the receivers for space-based solar are smaller and could be laid over e.g. farmland. Last, but not least, the atmosphere absorbs a lot of solar energy. In this model, the space-based rig is a lens, converting the well-absorbed frequencies that generate power into microwaves to which dry air is more transparent. If you can get a focussed beam, a SBSP rig could also be placed far enough out that it's less subject to Earth's day-night cycles. These factors boost its theoretical efficiency. I haven't run the numbers for several years. But they only become compelling if you have ISRU and in situ manufacturing of panels. I don't think SBSP is a beachhead market for asteroid mining. But it's feasible if we have it.
- flandish 3y ago
  > The problem is humanitarian crises don't pay. That’s only a problem if profit/exploitation is more important than humanity. IMHO, space based technology needs to be public owned (not corporate) and not allowed to profit, with its goals and designs fit to benefit humanity before profit.
- aperrien 3y ago
  One other important note is that is possible to put solar arrays in orbit that are always facing the sun, so they can deliver power 24 hours a day.
  - jacquesm 3y ago
    You'd need them to be in geosynchronous orbits unless you plan on powering the planet instead of the United States. And orbits that always face the sun are polar orbits, so you'd need a polar geosynchronous orbit. This would likely mean that the distance from the ground stations is way too large for meaningful power transfer. It would also require the whole installation to be somewhat movable. to correct its orbit as it slips over time because the installation is so large that different parts of it will be in slightly different orbits!
    - dabluecaboose 3y ago
      Quick quibbles: 1. Geostationary orbits are in 24/7 sunlight except for a short period each day near the equinoxes 2. Geostationary polar orbits do not exist. Geostationary orbits are, by definition, 0° inclined. A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day.
      - jacquesm 3y ago
        > A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day. It would offer a lot: the ability to send down an absolutely massive amount of power without having the corridor shift around so that it can be reliably routed around by air traffic. Having the equivalent of a microwave scythe moving across a large area would be kind of counterproductive.
bryanlarsen 3y ago
It's competitive for locations where the alternative is flying in diesel for generators. Some Northern locations are like that, although most have land or sea access on a seasonal basis. But the military flies a lot of diesel / kerosene.
xaellison 3y ago
Two reasons. 1. A microwave receiver on earth is much smaller than many solar farms, so we don't use a lot of our finite land for energy generation 2. This could actually bring solar to some geographies which aren't well suited to solar due to weather To achieve the energy transition, you need SO MANY solar panels and they will take up a lot of land. That land is most expensive near the very population centers which need the most power. According to Jesse Jenkins, to power America, "the solar farms are an area the size of Connecticut, Rhode Island and Massachusetts."[1] (this isn't the most precise source I could find, but it's reputable) [1] https://www.nytimes.com/2022/09/20/podcasts/transcript-ezra-klein-interviews-jesse-jenkins.html https://www.nytimes.com/2022/09/20/podcasts/transcript-ezra-...
- jacquesm 3y ago
  No, it's bs. Because of the double conversion you're never going to outperform solar here on earth and the cost of deployment undoes any advantage you might have had anyway. But: cool project and nice of them to get it bankrolled. > To achieve the energy transition, you need SO MANY solar panels and they will take up a lot of land. This isn't true. > According to Jesse Jenkins, to power America, "the solar farms are an area the size of Connecticut, Rhode Island and Massachusetts. The estimates are that it's anywhere from 10000 to 30000 square miles which is compared to the 3.8 million square miles of the continental USA an absolute pittance. Doing this by tightbeaming the output of an equivalent solar installation in space is ridiculous.
  - joak 3y ago
    Agriculture is 44% of US land, PV on an area <1% is enough to power America. And this 1% can (and should) be deployed in deserts
    - Teever 3y ago
      Not to mention we can make dual use of existing land in the form of roof top solar. The roof of every single new big box store should be covered in solar panels and we should start covering large parking lots in them too. Shaded parking that powers the area would be sweet.
gene-h 3y ago
The power it can provide is much more reliable than power provided by solar panels on earth, so it's more economically valuable than power by solar panels on earth. It would provide power at night and if the right microwave transmit frequencies are used, even if it's raining on the receiver. The loss through a thunderstorm isn't that bad.
forgot-im-old 3y ago
Space Solar is really coming from a DARPA initiative to build microwave beams from space as a weapon system to intercept missiles and other targets. The idea of selling solar power from space is another contrived commercial dual-use application to justify the technology development. A similar history was followed for Starlink which is not commercially viable without its basis in furthering SDI technology. https://en.wikipedia.org/wiki/Starlink#Military_capabilities https://en.wikipedia.org/wiki/Starlink#Military_capabilities
- kortilla 3y ago
  Starlink is separate and viable without Starshield. They are independent programs: https://www.space.com/spacex-starshield-space-force-contract https://www.space.com/spacex-starshield-space-force-contract
  - forgot-im-old 3y ago
    Starlink performance trends have shown it is not viable alone. https://en.wikipedia.org/wiki/Starlink#Subscribers https://en.wikipedia.org/wiki/Starlink#Subscribers
    - s1artibartfast 3y ago
      nothing about that screams "not viable" to me.
      - forgot-im-old 3y ago
        Those charts show each of the newest satellites buys ~400 paying subscribers (per additional satellite). Build, launch, operating for one satellite--while low for SpaceX--is too expensive for that to make sense. If they try to do more than 400 users per satellite, the service throughout plummets.
        s1artibartfast 3y ago
kragen 3y ago
in the near term (the next three orders of magnitude of human energy usage growth) it probably isn't practical rectenna arrays might have been a reasonable idea when solar panels were expensive. they're still reasonable if you're willing to use a microwave beam that's concentrated enough to be a devastating weapon of war. sunlight is 1000 watts per square meter, and that's already enough to heat up a tin roof or the interior of a car to temperatures that will burn or kill. if you boost that by a factor of 10 or 100, you could get a higher-density "power plant" on the ground that's cheaper than the equivalent solar farm but you still have to build the solar farm, you just build it in space. right now that's much more expensive, and, as jacquesm points out, rejecting waste heat in space is more difficult. there are a few possible ways that building it in space could be better: 1. if robots are mining asteroids for minerals, they can build solar panels in space that don't have to survive earth weather, or for that matter launch or reentry. plausibly they could be under a micron thick, thus using thousands of times less material than earth solar panels. conceivably you could even do this with terrestrial factories if you have cheap enough and gentle enough launch, which you don't, but maybe with bfr you will 2. if barbarians are mobbing your castle with pitchforks and torches, banning borax and methyl ethyl ketone, coercing you into swearing loyalty oaths, or threatening to put your family in ovens because of your ethnicity, you might prefer to have your solar panels somewhere they can't reach 3. to make the transition from a kardashev type 1 civilization to a kardashev type 2 civilization, obviously covering the entire earth with solar panels is insufficient, so you have to put them somewhere else 4. you can put the solar panels much closer to the sun than the earth is, so they produce much more power per unit area obviously none of these are relevant right now, but sooner or later they will be
- pfdietz 3y ago
  Your arguments are good, but waste heat rejection is not a problem for space solar power. The PV arrays double as their own radiators. I mean, this is how satellite PV arrays already do it. You do need radiators for the microwave transmitters, but these are spread out as well. Now, if you wanted to build a nuclear power plant in space and beam its power, then heat dissipation would be a big problem.
  - 3y ago
XorNot 3y ago
Microwave receiving antenna arrays aren't solid like solar panels on earth - they would essentially be a big grid of wire loops suspended above ground over maybe a square kilometre or so. While you probably wouldn't want to live underneath this, plants would grow and animals would not be harmed wandering in and out underneath it. So the benefit would be that substantially larger surface areas of renewables could be deployed with fewer maintenance concerns (i.e. thin antennas don't really care about dust, and present little cross section to being struck by debris).
heads 3y ago
Only half of our 500M square kilometre planet faces The Sun at any one time, and only half the surface (barren land and, more likely, oceans) could be used for solar panels. That gives us 125km2 of usable area. The atmosphere attenuates our 1300W/m2 of solar energy down to 300W/m2 so for a 125M km2 planet you only get 40PW of available power, or 5PW after 80% loss in solar panels and distribution. In terms of global energy demand we’re currently using 25PWh per year which is the equivalent of 3TW. Assuming oil runs out, politics annuls nuclear options, and we cover most of the planet in solar panels then peak terrestrial solar is three orders of magnitude away. Covering over everything with panels would presumably have devastating effects on the environment just as much as fossil fuels but if we limit to 1% coverage then we’re only one order of magnitude away from terrestrial solar being unable to power the world. It’s neither sunny nor midday all the time either so solar is starting to look dangerously close to not cutting it, and yet harvesting solar energy could be our only option for power for the next ten thousand years. I pulled all these numbers from Wikipedia and crunched them with GNU units — this is HN after all — but it doesn’t sound unreasonable to conclude that anything planet bound is going to be bounded by planet size. Moreover, if the goal is for power generation to have zero impact on our biome then we should probably not generate power within the biome itself.
- CorrectHorseBat 3y ago
  On that scale simply using power on earth will have a devastating impact on the environment and microwaving more power in makes it even worse.
  - heads 3y ago
    Yes and this goes into some awkward Thanos did nothing wrong territory. I’m sure there’s serious research out there on what the fundamental population limit of Earth should be if we are to bound it based on minimal ecological impact.
    - hiddencost 3y ago
      "Malthus" is taught in high school. The idea comes up all over intellectual history and has yet to pan out. One of these days.
kiproping 3y ago
Apparently, the main reason there is interest in this is because China is doing it too.
pfdietz 3y ago
It makes the power available 24/7, regardless of night and season. It also enables dispatch of the power to regions with higher demand, in ways that would be difficult with terrestrial transmission lines (for example, between northern and southern hemispheres.) The downside is cost and scale. Launching enough mass to power the world would also approach pollution limits for injection of water into the stratosphere and mesosphere. I have imagined it might be useable at small scale in specialized applications first, if the power is beamed by laser. This requires improvement in laser efficiency and cost, but it could be very nice to power long distance aircraft (at altitude above clouds) this way. The challenges are considerable, of course. Large scale use of power in space would not need transmission of that power, so could be an easier step. Latency insensitive servers there? The heat needs to be dissipated.

What’s the bullish story for why solar panels in space with microwave beaming is better than solar panels on earth?

simonebrunozzi 3y ago

There isn't. It's just another excuse to justify spending lots of money on things that make no sense.

temp0826 3y ago

Haven't you played SimCity 2000?

doctoboggan 3y ago

I haven’t done the math or really thought about it all that much but one reason could be that space has a lot of, well, space. You can build a huge array without wasting land that could be used for something else, condense the power down to a beam and send it to earth.

JumpCrisscross 3y ago

> What’s the bullish story for why solar panels in space with microwave beaming is better than solar panels on earth? Space-based solar power (SBSP) has three advantages over terrestrial solar: flexibility, footprint and theoretical efficiency. The classic case for flexibility is disaster zones; it's easier to set up receiving meshes than build new power plants. The problem is humanitarian crises don't pay. The real sell is military and mining. Beaming power to remote operations simplifies logistics. Footprint is minor, but worth mentioning: the receivers for space-based solar are smaller and could be laid over e.g. farmland. Last, but not least, the atmosphere absorbs a lot of solar energy. In this model, the space-based rig is a lens, converting the well-absorbed frequencies that generate power into microwaves to which dry air is more transparent. If you can get a focussed beam, a SBSP rig could also be placed far enough out that it's less subject to Earth's day-night cycles. These factors boost its theoretical efficiency. I haven't run the numbers for several years. But they only become compelling if you have ISRU and in situ manufacturing of panels. I don't think SBSP is a beachhead market for asteroid mining. But it's feasible if we have it.

flandish 3y ago
> The problem is humanitarian crises don't pay. That’s only a problem if profit/exploitation is more important than humanity. IMHO, space based technology needs to be public owned (not corporate) and not allowed to profit, with its goals and designs fit to benefit humanity before profit.
aperrien 3y ago
One other important note is that is possible to put solar arrays in orbit that are always facing the sun, so they can deliver power 24 hours a day.
- jacquesm 3y ago
  You'd need them to be in geosynchronous orbits unless you plan on powering the planet instead of the United States. And orbits that always face the sun are polar orbits, so you'd need a polar geosynchronous orbit. This would likely mean that the distance from the ground stations is way too large for meaningful power transfer. It would also require the whole installation to be somewhat movable. to correct its orbit as it slips over time because the installation is so large that different parts of it will be in slightly different orbits!
  - dabluecaboose 3y ago
    Quick quibbles: 1. Geostationary orbits are in 24/7 sunlight except for a short period each day near the equinoxes 2. Geostationary polar orbits do not exist. Geostationary orbits are, by definition, 0° inclined. A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day.
    - jacquesm 3y ago
      > A polar geosynchronous orbit, like you mentioned, would not offer much besides being over the same point on the Earth at the same instant every day. It would offer a lot: the ability to send down an absolutely massive amount of power without having the corridor shift around so that it can be reliably routed around by air traffic. Having the equivalent of a microwave scythe moving across a large area would be kind of counterproductive.

bryanlarsen 3y ago

It's competitive for locations where the alternative is flying in diesel for generators. Some Northern locations are like that, although most have land or sea access on a seasonal basis. But the military flies a lot of diesel / kerosene.

xaellison 3y ago

Two reasons. 1. A microwave receiver on earth is much smaller than many solar farms, so we don't use a lot of our finite land for energy generation 2. This could actually bring solar to some geographies which aren't well suited to solar due to weather To achieve the energy transition, you need SO MANY solar panels and they will take up a lot of land. That land is most expensive near the very population centers which need the most power. According to Jesse Jenkins, to power America, "the solar farms are an area the size of Connecticut, Rhode Island and Massachusetts."[1] (this isn't the most precise source I could find, but it's reputable) [1] https://www.nytimes.com/2022/09/20/podcasts/transcript-ezra-klein-interviews-jesse-jenkins.html https://www.nytimes.com/2022/09/20/podcasts/transcript-ezra-...

jacquesm 3y ago
No, it's bs. Because of the double conversion you're never going to outperform solar here on earth and the cost of deployment undoes any advantage you might have had anyway. But: cool project and nice of them to get it bankrolled. > To achieve the energy transition, you need SO MANY solar panels and they will take up a lot of land. This isn't true. > According to Jesse Jenkins, to power America, "the solar farms are an area the size of Connecticut, Rhode Island and Massachusetts. The estimates are that it's anywhere from 10000 to 30000 square miles which is compared to the 3.8 million square miles of the continental USA an absolute pittance. Doing this by tightbeaming the output of an equivalent solar installation in space is ridiculous.
- joak 3y ago
  Agriculture is 44% of US land, PV on an area <1% is enough to power America. And this 1% can (and should) be deployed in deserts
  - Teever 3y ago
    Not to mention we can make dual use of existing land in the form of roof top solar. The roof of every single new big box store should be covered in solar panels and we should start covering large parking lots in them too. Shaded parking that powers the area would be sweet.

gene-h 3y ago

The power it can provide is much more reliable than power provided by solar panels on earth, so it's more economically valuable than power by solar panels on earth. It would provide power at night and if the right microwave transmit frequencies are used, even if it's raining on the receiver. The loss through a thunderstorm isn't that bad.

forgot-im-old 3y ago

Space Solar is really coming from a DARPA initiative to build microwave beams from space as a weapon system to intercept missiles and other targets. The idea of selling solar power from space is another contrived commercial dual-use application to justify the technology development. A similar history was followed for Starlink which is not commercially viable without its basis in furthering SDI technology. https://en.wikipedia.org/wiki/Starlink#Military_capabilities https://en.wikipedia.org/wiki/Starlink#Military_capabilities

kortilla 3y ago
Starlink is separate and viable without Starshield. They are independent programs: https://www.space.com/spacex-starshield-space-force-contract https://www.space.com/spacex-starshield-space-force-contract
- forgot-im-old 3y ago
  Starlink performance trends have shown it is not viable alone. https://en.wikipedia.org/wiki/Starlink#Subscribers https://en.wikipedia.org/wiki/Starlink#Subscribers
  - s1artibartfast 3y ago
    nothing about that screams "not viable" to me.
    - forgot-im-old 3y ago
      Those charts show each of the newest satellites buys ~400 paying subscribers (per additional satellite). Build, launch, operating for one satellite--while low for SpaceX--is too expensive for that to make sense. If they try to do more than 400 users per satellite, the service throughout plummets.
      - s1artibartfast 3y ago

kragen 3y ago

in the near term (the next three orders of magnitude of human energy usage growth) it probably isn't practical rectenna arrays might have been a reasonable idea when solar panels were expensive. they're still reasonable if you're willing to use a microwave beam that's concentrated enough to be a devastating weapon of war. sunlight is 1000 watts per square meter, and that's already enough to heat up a tin roof or the interior of a car to temperatures that will burn or kill. if you boost that by a factor of 10 or 100, you could get a higher-density "power plant" on the ground that's cheaper than the equivalent solar farm but you still have to build the solar farm, you just build it in space. right now that's much more expensive, and, as jacquesm points out, rejecting waste heat in space is more difficult. there are a few possible ways that building it in space could be better: 1. if robots are mining asteroids for minerals, they can build solar panels in space that don't have to survive earth weather, or for that matter launch or reentry. plausibly they could be under a micron thick, thus using thousands of times less material than earth solar panels. conceivably you could even do this with terrestrial factories if you have cheap enough and gentle enough launch, which you don't, but maybe with bfr you will 2. if barbarians are mobbing your castle with pitchforks and torches, banning borax and methyl ethyl ketone, coercing you into swearing loyalty oaths, or threatening to put your family in ovens because of your ethnicity, you might prefer to have your solar panels somewhere they can't reach 3. to make the transition from a kardashev type 1 civilization to a kardashev type 2 civilization, obviously covering the entire earth with solar panels is insufficient, so you have to put them somewhere else 4. you can put the solar panels much closer to the sun than the earth is, so they produce much more power per unit area obviously none of these are relevant right now, but sooner or later they will be

pfdietz 3y ago
Your arguments are good, but waste heat rejection is not a problem for space solar power. The PV arrays double as their own radiators. I mean, this is how satellite PV arrays already do it. You do need radiators for the microwave transmitters, but these are spread out as well. Now, if you wanted to build a nuclear power plant in space and beam its power, then heat dissipation would be a big problem.
- 3y ago

XorNot 3y ago

Microwave receiving antenna arrays aren't solid like solar panels on earth - they would essentially be a big grid of wire loops suspended above ground over maybe a square kilometre or so. While you probably wouldn't want to live underneath this, plants would grow and animals would not be harmed wandering in and out underneath it. So the benefit would be that substantially larger surface areas of renewables could be deployed with fewer maintenance concerns (i.e. thin antennas don't really care about dust, and present little cross section to being struck by debris).

heads 3y ago

Only half of our 500M square kilometre planet faces The Sun at any one time, and only half the surface (barren land and, more likely, oceans) could be used for solar panels. That gives us 125km2 of usable area. The atmosphere attenuates our 1300W/m2 of solar energy down to 300W/m2 so for a 125M km2 planet you only get 40PW of available power, or 5PW after 80% loss in solar panels and distribution. In terms of global energy demand we’re currently using 25PWh per year which is the equivalent of 3TW. Assuming oil runs out, politics annuls nuclear options, and we cover most of the planet in solar panels then peak terrestrial solar is three orders of magnitude away. Covering over everything with panels would presumably have devastating effects on the environment just as much as fossil fuels but if we limit to 1% coverage then we’re only one order of magnitude away from terrestrial solar being unable to power the world. It’s neither sunny nor midday all the time either so solar is starting to look dangerously close to not cutting it, and yet harvesting solar energy could be our only option for power for the next ten thousand years. I pulled all these numbers from Wikipedia and crunched them with GNU units — this is HN after all — but it doesn’t sound unreasonable to conclude that anything planet bound is going to be bounded by planet size. Moreover, if the goal is for power generation to have zero impact on our biome then we should probably not generate power within the biome itself.

CorrectHorseBat 3y ago
On that scale simply using power on earth will have a devastating impact on the environment and microwaving more power in makes it even worse.
- heads 3y ago
  Yes and this goes into some awkward Thanos did nothing wrong territory. I’m sure there’s serious research out there on what the fundamental population limit of Earth should be if we are to bound it based on minimal ecological impact.
  - hiddencost 3y ago
    "Malthus" is taught in high school. The idea comes up all over intellectual history and has yet to pan out. One of these days.

kiproping 3y ago

Apparently, the main reason there is interest in this is because China is doing it too.

pfdietz 3y ago

It makes the power available 24/7, regardless of night and season. It also enables dispatch of the power to regions with higher demand, in ways that would be difficult with terrestrial transmission lines (for example, between northern and southern hemispheres.) The downside is cost and scale. Launching enough mass to power the world would also approach pollution limits for injection of water into the stratosphere and mesosphere. I have imagined it might be useable at small scale in specialized applications first, if the power is beamed by laser. This requires improvement in laser efficiency and cost, but it could be very nice to power long distance aircraft (at altitude above clouds) this way. The challenges are considerable, of course. Large scale use of power in space would not need transmission of that power, so could be an easier step. Latency insensitive servers there? The heat needs to be dissipated.