9 ms·

Fusion research is fundamentally good research to pursue, and vigorously. But in terms of energy for the world, we just happen to have an already made fusion pl

Fusion research is fundamentally good research to pursue, and vigorously. But in terms of energy for the world, we just happen to have an already made fusion plant some 92 million miles away. Its just an engineering problem of how to get more of it's wasted energy onto the earth using space solar arrays (Only one one-billionth of the Sun's total energy output actually reaches the Earth, now, per a google search...which seems too high, honestly).

tsimionescu 5y ago
Space solar arrays would be the perfect solution if we needed the energy in space. Since we need it on Earth, and since the sun is already sending exactly that energy to Earth, they are almost entirely pointless.
- tuatoru 5y ago
  In fact, space sunshades would be much more useful to us at this point than space PV.
causi 5y ago
Its just an engineering problem of how to get more of it's wasted energy onto the earth using space solar arrays Considering even the best solar panels have under 50% efficiency, increasing the total solar radiation to earth would be very bad for the climate.
- goodpoint 5y ago
  Actually it's true that increasing the overall input of energy in the planet atmosphere is bad. Yet, this also happens with nuclear, coal, gas, oil... The only solution is to capture the energy that is already being received from the sun in order to prevent it from heating up the atmosphere on site. E.g. solar panels on the desert and wind turbines
  - orthecreedence 5y ago
    > The only solution is to capture the energy that is already being received from the sun. Or stop screwing with it entirely (it worked fine without our help for quite a while) and build nuclear reactors everywhere, which scale wonderfully and work even when it's dark, cloudy, or shrouded in smoke.
    - goodpoint 5y ago
      missing the point much?
    - Galaxeblaffer 5y ago
      And also works in space..
- SubiculumCode 5y ago
  This is a silly comment. First, its not any different that creating your land-based fusion energy. Yes you are adding more energy into the system, thus more heat. In any case, space solar arrays that inefficiently convert electricity while in space would not be heating the earth directly. Just the inefficiencies in how that energy is used later.
  - HPsquared 5y ago
    It also applies to fossil fuels: the energy would otherwise be locked up underground. It'd be interesting to compare the energy directly released as usable heat from burning hydrocarbons, to the indirect increase in energy absorption over the life of the released greenhouse gases. Not sure, but I reckon the cumulative greenhouse effect would be massively more than the usable energy released during combustion.
  - causi 5y ago
    Yeah except that's not what he said. He proposed space mirrors with the photovoltaics on earth. Doing the inefficient part in space is fine.
- cinntaile 5y ago
  > increasing the total solar radiation to earth would be very bad for the climate. Citation needed. The radiation to earth varies already, sometimes we're farther away from the sun and the output of the sun isn't constant either. The earth seems to handle that just fine.
  - knodi123 5y ago
    > The radiation to earth varies already, sometimes we're farther away from the sun and the output of the sun isn't constant either. The earth seems to handle that just fine. That sounds remarkably similar to "how can there be global warming if we still have a cold season and a hot season". I don't say space-based solar arrays are necessarily a problem, but arguing that earth handles variations, as if the net total doesn't matter, is a little blinkered.
    - cinntaile 5y ago
      It's not like global warming necessarily has to do with the net total. It's the heat not getting out that's the biggest problem, hence why we focus on the gas(es) that keep the heat in?
      - knodi123 5y ago
        The net total is the sum of heat in and heat out. :-)
sbierwagen 5y ago
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.
gene-h 5y ago
The problem with space based solar power is RF interference. The transmitter will interfere with RF comms on the same band thousands of kilometers from the receiver. And I mean thousands. Figures 55 and 56 show how much RF power is incident a given distance from the center of the receiver for 2.4 GHz and 5.8 GHz.[0] 2.4 GHz is one of the best frequencies to use because losses through storms and what not are quite low. However, we now have bluetooth and wifi devices which operate at this frequency now. 1000 km from the receiver, the incident power is stronger than the minimum sensitivity of a bluetooth receiver. [0]https://www.researchgate.net/publication/348442155_Microwave_and_Millimeter_Wave_Power_Beaming https://www.researchgate.net/publication/348442155_Microwave...
pfdietz 5y ago
> Fusion research is fundamentally good research to pursue, and vigorously. Fusion research is applied. It is justified by the useful end goal, being an energy source, not by pure science. A pure plasma physics program would look very different (and likely not be able to justify the current fusion budget.) So, simultaneously advocating fusion research, while suggesting solar will win, is internally inconsistent.

tsimionescu 5y ago

Space solar arrays would be the perfect solution if we needed the energy in space. Since we need it on Earth, and since the sun is already sending exactly that energy to Earth, they are almost entirely pointless.

tuatoru 5y ago
In fact, space sunshades would be much more useful to us at this point than space PV.

causi 5y ago

Its just an engineering problem of how to get more of it's wasted energy onto the earth using space solar arrays Considering even the best solar panels have under 50% efficiency, increasing the total solar radiation to earth would be very bad for the climate.

goodpoint 5y ago
Actually it's true that increasing the overall input of energy in the planet atmosphere is bad. Yet, this also happens with nuclear, coal, gas, oil... The only solution is to capture the energy that is already being received from the sun in order to prevent it from heating up the atmosphere on site. E.g. solar panels on the desert and wind turbines
- orthecreedence 5y ago
  > The only solution is to capture the energy that is already being received from the sun. Or stop screwing with it entirely (it worked fine without our help for quite a while) and build nuclear reactors everywhere, which scale wonderfully and work even when it's dark, cloudy, or shrouded in smoke.
  - goodpoint 5y ago
    missing the point much?
  - Galaxeblaffer 5y ago
    And also works in space..
SubiculumCode 5y ago
This is a silly comment. First, its not any different that creating your land-based fusion energy. Yes you are adding more energy into the system, thus more heat. In any case, space solar arrays that inefficiently convert electricity while in space would not be heating the earth directly. Just the inefficiencies in how that energy is used later.
- HPsquared 5y ago
  It also applies to fossil fuels: the energy would otherwise be locked up underground. It'd be interesting to compare the energy directly released as usable heat from burning hydrocarbons, to the indirect increase in energy absorption over the life of the released greenhouse gases. Not sure, but I reckon the cumulative greenhouse effect would be massively more than the usable energy released during combustion.
- causi 5y ago
  Yeah except that's not what he said. He proposed space mirrors with the photovoltaics on earth. Doing the inefficient part in space is fine.
cinntaile 5y ago
> increasing the total solar radiation to earth would be very bad for the climate. Citation needed. The radiation to earth varies already, sometimes we're farther away from the sun and the output of the sun isn't constant either. The earth seems to handle that just fine.
- knodi123 5y ago
  > The radiation to earth varies already, sometimes we're farther away from the sun and the output of the sun isn't constant either. The earth seems to handle that just fine. That sounds remarkably similar to "how can there be global warming if we still have a cold season and a hot season". I don't say space-based solar arrays are necessarily a problem, but arguing that earth handles variations, as if the net total doesn't matter, is a little blinkered.
  - cinntaile 5y ago
    It's not like global warming necessarily has to do with the net total. It's the heat not getting out that's the biggest problem, hence why we focus on the gas(es) that keep the heat in?
    - knodi123 5y ago
      The net total is the sum of heat in and heat out. :-)

sbierwagen 5y ago

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.

gene-h 5y ago

The problem with space based solar power is RF interference. The transmitter will interfere with RF comms on the same band thousands of kilometers from the receiver. And I mean thousands. Figures 55 and 56 show how much RF power is incident a given distance from the center of the receiver for 2.4 GHz and 5.8 GHz.[0] 2.4 GHz is one of the best frequencies to use because losses through storms and what not are quite low. However, we now have bluetooth and wifi devices which operate at this frequency now. 1000 km from the receiver, the incident power is stronger than the minimum sensitivity of a bluetooth receiver. [0]https://www.researchgate.net/publication/348442155_Microwave_and_Millimeter_Wave_Power_Beaming https://www.researchgate.net/publication/348442155_Microwave...

pfdietz 5y ago

> Fusion research is fundamentally good research to pursue, and vigorously. Fusion research is applied. It is justified by the useful end goal, being an energy source, not by pure science. A pure plasma physics program would look very different (and likely not be able to justify the current fusion budget.) So, simultaneously advocating fusion research, while suggesting solar will win, is internally inconsistent.