Here’s an overview of the state of the art of needed technologies to beam power to earth, from almost three decades ago, when I was working at Rockwell. I ran across it in trying to reduce the entropy of my office. It’s funny how little has changed.
Sorry about the rotation; that’s how it scanned into the PDF. Just rotate it with your browser.
“Sorry about the rotation; that’s how it scanned into the PDF. Just rotate it with your browser.”
How do that. I think it might easier to look at it with smartphone.
Anyhow tilting my head, it seems undecided lunar power {providing power to Earth?] That is bad idea, the lunar power have limited amount of solar power in terms of earth’s global needs. Encircling small polar region, does seem to hard, encircling the whole moon, seems a bit problematic. And whenever somehow got to that point, exporting from Moon would be less 50 cent per kg- GEO gets more sunlight than lunar polar region {double the rest of moon} plus closer to Earth. Plus by that time, one will want cheap electrical power at GEO, if for no other reason make rocket fuel from water collected from the solar system {ie, space rocks}.Or rocket fuel in high earth orbit, could cheaper than rocket fuel on the Earth surface.
And at point, don’t even need to make rocket fuel on lunar surface- or you can import it, if you want to use chemical rocket fuel {or whatever use of LH2 or LOX the Lunatics need}.
I am thinking of how make freshwater lake in the ocean. It involves using pipelaunchers or one call them spar buoys. So general idea is make lake roughly hurricane proof. Though mostly thinking these things being off Californian coast.
So about 200 meter diameter, lake, total cost of about 10 million dollar, anchor to ocean floor {in less than 1000 meter of ocean water] and one use of spar buoys is to roughly bring anchor holding power up to near the surface- so it stays in one spot.
Main idea is for residential living, but related factor to that is to have a sewage system. Or one first use, could in terms of providing waste treatment for coastal cities.
Anyhow if had waste treatment in ocean, then just fresh water supply and residential electrical power.
From my browser I ‘printed’ it to a .pdf file and then opened that file with a PDF viewer that allows rotation.
Thought you were a computer guy Dave print to pdf really?, you can you just right click the link and save to computer or often their a download pdf button. Though in firefox button on the right side of the pdf window with the >> that bring up options to rotate.
I wanted a copy local on my machine. Is that ok with you?
Even if it wasn’t, nothing I can do to prevent it. I just wanted to make it accessible.
Thanks Rand.
I repeat:
Why you sending a bunch of raster images , through another raster conversion and compression routine? Even if it none noticeable loss of quality.
In Brave or Chrome, there should be a button on the upper left that allows rotation of a PDF. Not sure about other browsers.
Ok, thanks, that works- and I am using Chrome.
Interesting. Regarding Sphere:
SPS sphere or Cylinder
1000 meter diameter sphere, surface area: 3.14×10^6 square meter
1000 meter tall 500 meter diameter:
circumference: 1,570.795 times 1000 = 1,570,795 square meter
Sunlight cross section: 500,000 square meter
Cross section of 1000 diameter sphere: 500 x 500 x 3.14 = 785,397.5
The Section which gets most sunlight, is 45 degree North, South, East, and West:
circumference of 1000 meter diameter sphere:
3,141.59 / 360 = 8.726638888 meters per degree. times 45 = 392.69875
a 392.69875 meter radius circle is 484,471.84548 square meter
as compared toi cylinder
500 meter diameter cylinder: 1,570.795 / 360 = 4.3633194 times 45 degrees =
196.349375 radius or 392.69875 diameter times 1000 meter tall:
392,698.75
Effective area of 1000 diameter sphere of 3,141,590 square meter: 484,471.84548
Efective area of 1000 meter tall and 500 meter of 1,570,795 square meter: 392,698.75
What do I mean by effective area? at 45 degree latitude distance from Zenith, one has to
point an array at 45 degree to be perpendicular to sunlight. They don’t have to be perpendicular
to sunlight, they can flat to surface of sphere. Or if tilted say 20 degree they get roughly
full sunlight, but then they shadow panels which are further away from the zenith point. So probably going
to keep level to sphere, but beyond 45 degree it gets progressly less effective.
Another metric is simply the cross section- you not going to recieve any sunlight then disk area of sphere
3.14×10^6 square meter vs disk area of 785,397.5 square meter or 1/4 total area
With Cylinder, you not going to any sunlight at ends and half sunlight of cylinder walls,
1,570,795 square meter / 2 = 785,397.5
Or 1/2 sphere gets sunlight or daylight, 1,570,795 square meter, effective: 484,471.85 square meter.
1/2 cylinder gets sunlight, 1,570,795 / 2 = 785,397.5 square meter, effective 392,698.75 square meter.
And use one end of cylinder as MW antenna.
One also chop off a “polar region” of a sphere for the MW antenna, because the “polar regions”
on the sphere would always get very little sunlight.
Or alternatively if attached cylinder to polar region, the wall of cylinder gets more sunlight and could also be the
MW antenna.
If you’re running Linux, you can easily rotate the pages once you’ve installed pdftk .
From a command line, run
pdftk SpaceSolarPower.pdf cat 1-endleft output output- filename
The “endleft” is actually two key words run together: “end,” specifying the end of the range of pages to print (“cat”), and “left,” specifying that they’re to be rotated 90 degrees to the left.
The pdftk utility can do lots of other things too.
P.S. That’s not a typo in the command line: the keyword “output” is followed by the desired name for the output file.
When I was at DARPA, the subject of space solar power came up a lot. I had two ideas for the last mile problem, myself.
First was an in space, solar powered factory that would produce polonium 210. A solar-powered linear accelerator would be used to generate spallation neutrons, which would in turn be used to bombard stable bismuth 209 targets to form bismuth 210. The latter is radioactive, with a half-life of about 5 days, and decays by beta emission to polonium 210 – which has a half-life of 138 days, yields 676 MW-hr/kg energy by alpha decay, and ends up as stable lead 206.
The second was to create large, flat high-altitude (100 kft) balloons topped with solar panels whose band-gap was the same as eye-safe lasers (near infrared). The balloons would be tethered over a military operations site using Zylon fiber cables (the highest strength to weight polymer out there). A solar power satellite could then beam power through infrared diode lasers with high conversion efficiency, and none of the side-lobe losses associated with microwaves.
You’d be surprised at how dismissive other DARPA PMs are of new ideas, given that their chief criterion for project selection is that it be “DARPA hard.”
I forgot to mention that the polonium 210 would be transported to earth via small reentry vehicles. It’s the small upmass of bismuth 209 and the small downmass of polonium 210 (each kg equivalent to 58 metric tons of oil) that makes it worthwhile.
And the efficiency of transmuting bismuth into polonium with a linear accelerator is how much?
If polonium is an alpha source, can you convert the charged alpha particles directly into electricity, or do you need to generate heat and run a steam turbine as with neutronic nuclear energy sources?
I don’t have an estimate for the production efficiency. That would require a rather elaborate study, and we never got to that point. Some of the factors involved are: use of rejected heat from neutron targets to recover wasted energy, orbital placement of SPS to maximize Sun time while permitting heat rejection, orbit altitude to minimize up and down mass delta v requirements, etc. It’s a big effort.
You could generate electricity directly: https://en.wikipedia.org/wiki/Atomic_battery
Of interest from deep sfnal antiquity: “Tom Swift and His Outpost in Space” features a space station whose main purpose is the recharching of solar-atomic batteries. The station is serviced by reusable crew rockets that look almost exactly like the 2018 version of BFR (the one with three leg-fins and nose canards). The rockets are initially described in “Tom Swift and His Rocket Ship” as being fueled by alcohol and ozone (the latter manufacture in flight using the solar-atomic battery charging process).
World oil consumption: 92.9 e6 barrels per day at 6.86 Barrels/ton gives 13.7 e6 tons per day. 58 tons per kg = 236,000 kg/day of Po. More than I’d want in my yard.
Oils consumption:
https://www.eia.gov/outlooks/steo/report/global_oil.php
A 1000 MW coal-fired powerplant consumes 10,000 tons of coal per day. Assuming 40% efficiency (most plants are at about 41%), the same output could be achieved through the decay of 88.76 kg (0.098 tons) of Po 210. That’s a factor of 100,000 reduction in resources. However, bismuth 209 is probably not as abundant as coal.
Is the Thermal solar power satellite concept dead? That is reflective mirrors to heat a boiler to drive Stirling engine generators. All I see are solar cell concepts.
I don’t know if it’s any more dead than powersats in general, but with the advances in solar-cell technology, it probably doesn’t trade well, give the maintenance issues. If you get a leak in the system(s) with the working fluid, it’s a royal PITA in vacuum and weightlessness.
That’s more than made up for by the efficiency. The cold side is -270C, so the hot side only needs to be about 30C to give a 99% efficiency.
Commercial solar panels are doing very well if they achieve 14%.
My wife worked on qualification of the cryocoolers for the James Webb Space Telescope, and I got interested as a result. These are Northrop-Grumman products, and are the best on the market. They have electromagnetically driven opposing pistons (cancelling vibration) driving helium gas into resonance, and pumping heat from one end to the other (they get down to about 4 K with very little input power).
Like every thermodynamic cycle, these can be run in reverse to generate power across a temperature difference. I invited an NGC guy into DARPA to talk about it, and they have demonstrated 30% thermal efficiency (electric power out versus heat in), and that’s without either going to super high hot end temperatures, or having the cold end at a temperature one could achieve in space. The efficiencies realistically achievable, in my opinion, are on the order of 90%. The moving parts count is small (2), and there is no maintenance required, or even possible.
I remember that Gerard O’Neill used to say that if using ET resources, solar thermal becomes more competitive with solar PV. What drove them to PV was the overwhelming need to reduce system mass.
Has anyone managed to make photovoltaic cells from regolith simulant? I haven’t heard of it and a quick Googling didn’t find much beyond experiments with film deposition.
I don’t think so. That presentation said that it was a crucial technology, but it has never been funded, as far as I know.
If Starship can throw 150 tons into LEO per shot for 2 mil eventually, how does that change the economics?
“If Starship can throw 150 tons into LEO per shot for 2 mil eventually, how does that change the economics?”
This is from 2012 years before Starship so maybe he has changed his mind but:
“One thing we learned today: While Musk loves electric cars and spaceflight, there’s one thing he hates: space solar power. “You’d have to convert photon to electron to photon back to electron. What’s the conversion rate?” he says, getting riled up for the first time during his talk. “Stab that bloody thing in the heart!””
https://www.popularmechanics.com/technology/a8101/elon-musk-on-spacex-tesla-and-why-space-solar-power-must-die-13386162/
“I can relax assumptions all day. I can grant 100% transmission efficiency, $10/kg orbital launch costs, complete development and procurement cost parity, and a crippling land shortage on Earth. Even then, space-based solar power still won’t be able to compete, because the antenna receiver alone is basically a solar plant in disguise.”
https://caseyhandmer.wordpress.com/2019/08/20/space-based-solar-power-is-not-a-thing/
Albeit one (a solar power plant in disguise) that could generate solar powered electricity 24/7 regardless of night/weather/season etc; but I suppose his point is made.
It’s the infrastructure. SSPS will need maintenance, esp. if there are active components (like rotational arrays). Essentially you need a near permanent crewed presence in space to maintain the things. They aren’t viable if you only build one. You need probably a few dozen spaced across GEO. Then there is the problem of interference with comm sats also at GEO. The ITU and FCC remain persnickety about that. But I think putting your power source 23,000 miles out into space when you could do it on the ground with solar and a good battery is why Elon looks askance. The maintenance of that is not pie in the sky. But O’Neill was looking for an ends that justify the means, not a justifiable end in and of itself. But also that’s strictly the commercial application, military might be another story. Or not.
“Albeit one (a solar power plant in disguise) that could generate solar powered electricity 24/7 regardless of night/weather/season etc;” Which isn’t a small albeit. IIRC, typical solar installations require 8-10 times as much capacity as the base load to deal with this very fact. Also, would have preferred he actually run some figures on the cost of land rather than just saying it won’t make a difference. Also, how much of decreased cost on earth is due better technology and how much is due to subsidies?
Yes. Thought about that after I posted it. An Japan is reportedly consistently interested. Land isn’t cheap/abundant in Nippon. If they leased land in some foreign country said electricity probably couldn’t be easily directly added to Japan’s electric power grid. Unlike the US they don’t have vast amounts of cheap desert land where solar cells could be installed. The satellite receiving point (antennas) could be placed on Japanese land possibly for more than one SPS at a time.
Yeah, space based solar power for ordinary Earth consumption doesn’t seem practical. Special purpose applications like supplying electric power for military outposts in logistic isolation might be practical.
“Stab that bloody thing in the heart!””
SPS aren’t going to happen in the near term.
By the time one gets SPS, you might already have space elevators. And/or you could get SPS for Mars before you get them for Earth surface.
Only value I see for a space elevator is running a extension cord down it. Or harvesting gravitational energy, by dropping water from orbit.
SPS need the price of electrical power in orbit to be around the price of electrical of earth surface {or Mars surface}- and using an economy of scale drop the cost of electrical power in space below the price of electrical power on Earth {or Mars} surface.
A part of whether lunar water is mineable is the price of electrical power on the Moon {and price of electrical power on Mars surface has be to related to having towns on Mars}.
For lunar water to mineable the price of electrical power on lunar surface has to be about $100 per kw hour {or less} which is about 100,000 times the price of electrical power on Earth. And if the Moon is going to involved with SPS, the price of electrical on the Moon has lower to about $1 per Kw hour {only about 100 times of price of electrical power on Earth]..
I would say price of lunar electrical power is more critical than price of lunar water. And Mars settlement the price water is more critical than the price of electrical power- or Mars water has to be about $1 per kg or less or only about 100 to 1000 times the price of water on Earth.
Anyways, I think starting price of electrical power on the Moon, can be $100 per kw hour {for million of watt hours}. And, this means, electrical power delivered in any quantity and at any time that the consumer wants it- in same sense comparable to how electrical power is sold on Earth- and in terms of Mars it’s water available whenever you turn on the tap.
Or let’s look at some kind oppressive governance of a town on Mars, rationing electrical power, is less of problem than rationing the amount of water you can use. Both are evil/bad, but limiting water use {laws prohibiting and fining “over use”} is worse.
Musk’s Starship might lower the price of electrical power on the Moon to $10 per kw/h. If lunar economy starts at kind of price, it seems it moves everything faster- shortening time needed to get to having SPS. But I still think it would take couple decades.
You know who else is not keen on space solar power (for terrestrial use): Pete Worden. He’s someone who is willing to think big and is knowledgeable. I take his reservations seriously.
Hey, “Shuttle Experience Points The Way To Fully-Reusable Systems For Low Launch Costs At High Flight Rates”
This has to be accurate — it is in Rand’s slides.
I was working for the Shuttle prime contractor at the time…
Killer “action titles” on those slides! Great proposal-ese!
The US military is very interested in space solar power to reduce the logistics infrastructure load at isolated installations like forward operating bases (FOBs). In remote parts of Afghanistan or Iraq, fuel to run generators sometimes had to be delivered by helicopter due to the dangers of attacks against truck convoys. The full cost of a gallon of fuel could easily exceed $50 at those locations. A space solar power experiment is flying on the X-37 right now. It wouldn’t necessarily have to be a GEO satellite for this to work. If you had several power satellites in LEO, they could beam down energy when within line of sight of the intended locations. The energy could be stored, either in batteries or something like ultracapacitors, and used as needed. As an example, suppose a FOB needed an average of 100 kwh to function. If you provided sufficient storage to meet that demand and then used a high power energy transmission, even relatively short passes of LEO satellites could be enough if you could get a few satellites passes each day.
“It wouldn’t necessarily have to be a GEO satellite for this to work. If you had several power satellites in LEO, they could beam down energy when within line of sight of the intended locations.”
It seems one could have them in Sun-synchronous orbit. And seems a lot of them and on on small side of things. Or sort of use satellites you got, augment electrical power storage and put powerful gun on it.
So talking about 50 to 100 satellites, all the same.
One application of space based solar power production I think has merit is dual-use spacecraft.
For example, an unmanned solar-electric-propulsion cargo tug might also serve dual use, as an orbital solar power satellite for surface power on the Moon or Mars. Solar-electric-propulsion with a useful sized cargo load might have solar panels which generate electric power in the megawatt range.
After arrival in orbit, the SEPS tug drops off the cargo, and beams power down to the surface. This power supply might be particularly useful for a large pressurized lunar rover.