Lunar Solar Power
If someone could explain this to me, I would be most appreciative: Apparently, two Ph.D.-carrying professors of physics at the University of Houston believe in the validity of “lunar solar power” (something that had escaped my notice altogether until just now). The concept: collect the energy incident on the moon and then beam it to Earth.
They don’t seem to say how they propose to accomplish that first task. Doesn’t it seem strange that if we’re having a hard time coming up with a cost-effective way of collecting solar energy right here where we live, that it might be even a teensy bit harder on a rock 250,000 miles away that is constantly being bombarbed with space debris?
In any case, these professors seem quite serious about the whole thing; I just don’t understand that. I receive lots of ideas like this, but normally from people who are clearly crackpots. My favorite are the people who have a clear contempt for science as mindless conformity to meaningless rules, WRITE IN ALL CAPS, have a childish command of speling and gramur, and use lots of exclamation points!!!!
Lunar solar radiation does not have to deal with the atmosphere or clouds. After it is collected, it can be sent to Earth using microwave radiation, which can penetrate the atmosphere much more readily. Orbital solar arrays work on the same principle.
If you can manufacture the solar arrays on the moon, using local resources, it might even be cost effective.
In other words, it’s good science fiction in the sense that the physics work. Getting the technology to work in a cost effective manner is another question, but I certainly wouldn’t rule it out in a 20-50 year time-frame.
What % losses are there in overall efficiency due to the Earth’s atmosphere? I thought they were fairly minor. Also, isn’t it extremely unlikely that we’ll still need such a radical solution in that time-frame? And yes, there’s nothing that makes this physically impossible, though the economics are so disadvantageous that it’s hard to imagine smart, pragmatic people taking this seriously. I’m guessing Glenn Doty will be along here soon…
I’m suspicious – the huge expense of multiple manned moonshots (lunar landings included), long-term human presence in 1/6 Earth’s gravity, the risk of gamma bursts, University of Houston (in the oily state of Texas)… Things that make me go, “Hmmm…”
Ok Craig, I’ll bite.
Tom is right that this is Science Fiction. One of my favorite Sci Fi authors in my youth – Larry Ninnev – used this approach in several of his science fiction novels. Note he also wrote the Ringworld series – where they made a giant metal disc thousands of miles wide that circled a star (millions of miles in diameter) – so his work shouldn’t be considered plausible under our current or any near-term paradigm.
🙂
The Earth’s atmosphere trims quite a bit of our power away… If you look only at ideals, the outer atmosphere receives ~1360 W/m of incident solar energy, while the Earth’s surface – when perpendicular to the radiation with no cloudless (least atmospheric absorption), essentially at the equator at noon, receives ~1000 W/m.
The average insolation of the Earth is ~250 W/m, but of course this includes night-time.
If you had an orbital collector, you’d have the full 1360 W/m for some length of time >12 hours/day (the actual amount of time depends on the distance of the orbit). For them moon this would be complicated by the moons slow rotation… But the average would work out to ~680 W/m on the moon, and higher than that in free orbit.
That sounds nice. However, the first problem is getting it up there. It costs ~$30,000/kg to launch something into space (this may be an outdated estimate with Musk’s SpaceX dragons, while I have a seething dislike of EV’s, I have a great respect for what Musk has been doing in revolutionizing the space vehicle), and far more than that to launch something to the moon. So it would take something on the order of tens of thousands of years to pay back the energy collected by an orbiting collector (that’s a guess)… But there’s also a problem with calibrating and focusing a microwave beam over that distance. Really focusing the energy for more than a few dozen miles is simply beyond our capacity to do… We would have to beam it using a high-energy laser, which means you’ll still face the losses from the atmosphere, and then you’ll have to re-collect it on the ground with another solar collector…
It’s the ultimate Rube Goldberg idea – how can we maximize costs and complexity to do a simple thing. It would be a better idea to set up solar collectors on the ocean floor.