21 ms·

Powering the Lunar Base

176 points by mercutio2 5y ago

andyxor 5y ago
the only answer is nuclear, simply because of energy density required for space applications. the creators of the original solid-core Krusty/Kilopower reactor are trying to commercialize the tech, I hope they have enough funding (@sama, I hope this is on your radar) https://www.spacenukes.com/ https://www.spacenukes.com/ This is the first fundamentally new reactor actually built and tested by NASA in more than 50 years (vs. countless paper designs) https://www.nasa.gov/mission_pages/tdm/fission-surface-power/index.html https://www.nasa.gov/mission_pages/tdm/fission-surface-power... EDIT: I highly recommend watching the presentation by David Poston "Space Nuclear Power for Mars" https://www.youtube.com/watch?v=luQfEYs2L0w https://www.youtube.com/watch?v=luQfEYs2L0w
- baybal2 5y ago
  I don't see battery storage as a problem for the first outpost, but yes, kilopower reactors were made exactly for this. Another option for early missions is just to limit them to 14 days. Heating of the base can be achieved by preheating the regolith deep beneath the surface. With regolith density we know, it should be well feasible. Thermal insulation can be made very efficient in space because there is no atmosphere. I see a nuclear/rtg base power for life support, and solar powered regolith smelting following the 14 day cycle.
  - Robotbeat 5y ago
    That’s pretty reasonable. Particularly since nuclear (fission or radioisotope) produces a lot more heat than electricity (thermal to electrical conversion efficiency is just 23% for Kilopower and 3-9% for RTGs), so using it for base heating during the night is a much better argument. And even some solar powered rovers like Spirit and Opportunity used small radioisotope heat sources to stay warm.
- Robotbeat 5y ago
  “The answer is nuclear” is repeated often but often is an innumerate answer. Kilopower for most uses in the inner solar system performs considerably worse than solar. The power to weight ratio of Kilopower is about 6-7W/kg, no better than old time RTGs. UltraFlex solar panels do about 150W/kg near 1AU. Nuclear in the lunar case may be useful for base power due to the long lunar night which makes storage pretty heavy, but nuclear is actually usually WORSE performance than solar, producing much less power for the same mass. It’s only in the outer solar system around Jupiter or in niche cases like lunar night where nuclear has a solid lead on solar. Otherwise it’s similar or worse, besides being a lot more expensive. ~$100 million for 10kWe Kilopower.
  - andyxor 5y ago
    i think you are missing the point of Kilopower, it was to build a working micro reactor prototype on realistic timeframe and actually ship it, they have designed the extension of this to MW scale where energy density is order of magnitude better. Nuclear scales better than any other source of energy. How many sq feet of solar panels do you need for 1, 10, 100, 1000, 10000 MWe, now translate it to lbs and $$$ cost (including shipping to the moon or mars base), also consider dust and lunar night conditions affecting solar use. if you look at scaling it vs. weight and cost (including maintenance and replacement panels over 20-30 years), solar is no competitor to nuclear.
    - Robotbeat 5y ago
      No, the larger nuclear power plants (50kWe) NASA has developed to reasonable TRL are still around the same power to weight ratio. Nuclear, in addition to everything else like the dynamo and the reactor itself, requires heavy radiators. Also, Kilopower has a SHORTER lifespan of about 15 years whereas solar can last 30-50 years (solar degradation is much slower than is often claimed, at least when we’ll engineered and in the absence of high humidity) as there’s no moving parts and nothing to refuel. Remember, terrestrial nuclear reactors are regularly refueled (annually?) and maintained. The traditional argument has always been that nuclear scales better than solar, but usually such comparisons are looking at sandbagged, outdated solar panels and very low-TRL nuclear designs relying on super high rejection temperatures (ie unrealistic) or shorter lifespans. I’m not anti-nuclear by any stretch, and I fully support increased funding and deployment of nuclear power, but I think there has been a lot of hand waving by some nuclear advocates. If you look at actually achievable, near term nuclear designs, none of them perform anywhere near as good as solar does in orbit near 1AU, and it’s not even close. It’s surface applications or outer solar system where nuclear has a chance against solar. Outside of those cases, solar is much more powerful for a given weight (meaning cheaper to transport) plus being far cheaper to build and not requiring special launch vehicle risk mitigations (currently, the only nuclear-rated launch vehicle is Atlas V… and every nuclear launch must be approved by the executive branch). (A human Mars base may benefit from a mix of power sources for resiliency purposes.)
- shkkmo 5y ago
  On the moon, Nuclear has basically the opposite problem of solar: Long, hot days mean that nuclear power generation is hard to cool during the lunar day. This means that nuclear for the moon is basically directly competing with batteries and other storage solutions in terms of weight/risk/difficulty.
go_elmo 5y ago
Looking forward for the re-boost of nuclear space-technology so many scientific opportunities!
papito 5y ago
This doesn't even mention Helium-3? Come on.
- ncmncm 5y ago
  Lunar Helium-3 is a mirage. There is no plausible scenario where trying to gather lunar He-3 turns out well.
h2odragon 5y ago
dont miss the bit on "remotely beamed microwave power." "silly idea" it may be but now i want a mega-maser as described for my own sporting purposes.
- hereforphone 5y ago
  Do they expect to outdo the sun?
  - h2odragon 5y ago
    In one very specific frequency band, at one comparatively small place, yes. by a large amount. Ocean vs firehose. Or, better: In the same way every "daytime headlight" you see is outdoing the sun.
    - hereforphone 5y ago
      Which 'frequency band'? https://www.researchgate.net/figure/Spectral-power-density-of-solar-radiation-5_fig1_268822609 https://www.researchgate.net/figure/Spectral-power-density-o...
      - rrss 5y ago
        microwave
        hereforphone 5y ago
        Brilliant answer
      - h2odragon 5y ago
        > Achieving a beam that narrow (1/2000000 rad) from the Earth would require a phased array spaced out over a much larger area, at least 200 km at 5 Ghz (6cm). I doubt they'd want a very large band but in microwave work I dunno what counts as "large". and i'm a little afraid to go look deeper into this because i'll wind up tearing up junkyard microwave ovens and building something i shouldn't.
mschuster91 5y ago
I wonder... we used to use electrically heated stone as storage medium for heating homes, until it became uneconomical due to energy price hikes. A lunar base could electrically heat up a lot of easily mined rock and use that to store enough heat to keep the base warm enough?
- bbojan 5y ago
  Yes, but that's not an issue here. Life support would require a lot of electrical energy, not heat.
  - mschuster91 5y ago
    What do you need for basic human life support? Light, oxygen generation/CO2 removal, water, and electricity for vehicles and work appliances. Oxygen and water can be stored in tanks sufficient enough to ride out the 14 days dark cycle, LED lighting is extremely efficient (especially if everything is under 9m of moon soil, so no light can escape useless to space), the only thing that may be a problem is CO2 removal - no idea how much energy that uses.
    - gpm 5y ago
      I think CO2 depends heavily on what you're doing with it. You filter CO2 out of the atmopshere using zeolite beds at relatively low temperature/high pressure, you then recharge those by venting the beds at relatively high temperature/low pressure. If you're venting the CO2 to space (they do on the ISS), I don't have numbers/proof to back this up but you probably don't need much energy at all. You just pass air through the absorbing bed at ~1ATM (i.e. with a fan), and a heat exchanger from the venting bed to the absorbing bed might even be enough to keep the temperatures in the right range. If you're capturing the CO2 afterwards however, you probably need some more energy-expensive machinery. Again, I don't have numbers, but you're definitely talking about running a compressor to force the venting CO2 into a tank now, and you might want to compress the absorption side as well to get a bigger pressure gradient. The only real use of that captured CO2 is to recycle it into something useful (e.g. O2 and CH4 using the sabatier reaction), and that reaction is going to be endothermic, but you can probably just store the CO2 until you have sunlight and do it then.
unchocked 5y ago
I find it odd that the author dismisses hydrogen storage largely based on the requirement to mine water for electrolysis and then goes on to propose using ~12,000 tonnes of water for thermal energy storage.
- baybal2 5y ago
  Storing water does not require pressure vessels, nor cryogenic coolers.
  - errantspark 5y ago
    It pretty definitely requires pressure vessels if you care about it's phase.
    - natosaichek 5y ago
      Well it requires a closed container that maybe has to take a few psi of water pressure. It doesn't require anything that can tolerate thousands of psi like hydrogen does.
      - errantspark 5y ago
        Oh for sure the storage problem is much much more difficult to solve wrt hydrogen than water, I was just being pedantic.
      - kolinko 5y ago
        You can store hydrogen in lower pressures if you don’t care about the amount of space it takes.
        credit_guy 5y ago
        That's a brilliant idea. You could store the hydrogen in some big balloons. There's no buoyancy on the Moon, so you don't need to anchor these balloons. You need to cover them with a dome to protect them from micrometeorites, but when you establish a Moon colony, building domes is the name of the game. At normal (on Earth) room temperature and pressure, a balloon with a radius of 10m holds about 60 kg of hydrogen. I did some back of the envelope calculations, and that would be enough to provide about 2 kW of power for the length of the lunar night (14 days).
Diggsey 5y ago
How about two/three sites around the Shackleton crater which beam power back and forth wirelessly across the crater as each site goes in and out of sunlight?
- edgyquant 5y ago
  This is a sexy idea. I don’t know if it would work, but it would be fun to work on
- ncmncm 5y ago
  Cabling would be the thing. Shackleton Crater might make an awesome radio telescope.
  - ncmncm 5y ago
    ... or even better, infrared telescope. (Both, really, at once.) With the mirrors separated from the focus by miles, they could be simple optically flat surfaces, as many as you like; and so far apart, the resolution would be unmatchable. It would probably be most useful for deep-field imaging, because to can't point it; you rely on it happening to point at something interesting, which likely means stars in galaxies very far away.
- seg_lol 5y ago
  From a linked research article on the main site, they had a compelling plan bounce energy around with mirrors so you don't have reconversion losses. Tracking mirrors and solar panels. The light from the sun is highly collimated.
  - Diggsey 5y ago
    Interesting, but surely the last thing you want is complex mechanical systems involved that will quickly wear out due to lunar regolith, or having to transport large mirrors to the moon? Sure you get losses from wireless transmission, but you can always just add more solar panels, as they're cheap, lightweight and compact. You only need a small amount of power to keep things going during the 14 days of darkness, so you can avoid transfer losses by doing the intensive stuff during the 14 days in the sun.
state_less 5y ago
I’d imagine they’ll need to do a number of electrochemical reactions to make oxygen to breathe and fuel to burn, etc... Use an oversized solar array and store the chemical products in tanks. Batteries are chemical stores too, no? Anyhow, not sure of the efficiency of all these reactions, but more panels could help until further reaction improvements can be made.
- Diggsey 5y ago
  The article does consider that option via splitting and storage of water, and then recombination via hydrogen fuel cells. According to the article the mass of the storage vessels needed to store 2 weeks of pressurized hydrogen and oxygen are comparable with the mass of batteries you'd need, although I haven't done the calculations myself... Intuitively I would expect this to be more efficient than batteries though.
  - gpm 5y ago
    I think the point here is rather that power load at night can be much lower than power load during the day, if most of the energy is going to optional processes like making oxygen and/or rocket fuel.
  - ncmncm 5y ago
    If you are storing gases at the lunar pole, liquid is the right form. Then the tanks are very light and cheap. Liquifying gases is very easy there.
nkingsy 5y ago
How many starships full of copper would be required to run a hvdc line between enough points to get constant coverage?
- baybal2 5y ago
  Moon is 10% aluminium, with that constrain, I doubt copper will see much use for long range transmission.
  - voakbasda 5y ago
    Mining and refining aluminum takes a huge amount of power, so you’re back to hauling tons of wire to build the initial infrastructure. Mining is definitely the way to go after that bootstrap stage, but this question remains: is this the best bootstrap plan?
    - gpm 5y ago
      But one of the key observations from this article is that we won't be power constrained, we will be constrained by consistent power, since power at night costs far, far, more than power during the day. If we can ship some extra solar panels up and refine aluminum during the day, to reduce the cost of power at night, it seems likely to be entirely worth it.
    - inglor_cz 5y ago
      You have a shitton of solar power at your disposal during the lunar day. Lunar surface is raked by the full solar constant of power, no atmosphere = no attenuation. That is quite a sizzle. So you can smelt a lot of aluminium during the fortnight when the sun is up. And build a web of wires around the entire Moon so that during the cold and dark lunar night you can get power from the other side of the Moon.
- dredmorbius 5y ago
  Direct transmission (e.g., microwave beamed power) might be a more viable alternative. You'd need high towers, and lots of them (smaller radius, nearer horizon), but wouldn't have the mass budget of running wire.
gpm 5y ago
I'm a fan of this comment: https://caseyhandmer.wordpress.com/2021/04/25/powering-the-lunar-base/#comment-5194 https://caseyhandmer.wordpress.com/2021/04/25/powering-the-l... TL;DR - Just don't be there during long winter nights.
- Gatsky 5y ago
  Agreed, it would be quite an operational hazard and probably an unethical experiment to leave astronauts on the moon for long periods. Factoring in appropriate safety margins for equipment, supplies, physiology and rescue flights, they could only stay there a few months at a time in any case.
fnord77 5y ago
another Musk fanboi, redoing the speculative work that NASA did in the 70s and then claiming credit for it.
ttul 5y ago
So, nuclear then.
- ncphil 5y ago
  Yeah. Nuclear may not make sense here on Earth -- even Antarctica -- where the environmental and human health consequences are practically unavoidable (especially when implemented by the lowest bidder), but space outside of LEO is another matter. NASA is in fact looking at it. https://cen.acs.org/energy/nuclear-power/NASA-thinks-nuclear-reactors-supply/98/i19 https://cen.acs.org/energy/nuclear-power/NASA-thinks-nuclear.... Although the idea of migrating researchers to a sunlit base when night falls at their primary base has potential, it's probably going to be more practical to stand up a whopping big RTG or full-on fission reactor a distance off from the habitats. Space borne fission plants are going to be necessary anyway if we're ever going to send people to the outer solar system (Jupiter, Saturn, Uranus, Neptune). We might as well learn how to make them work on the Moon ("It's a damned research project!").
  - devoutsalsa 5y ago
    Nuclear is basic the safest (and climate change friendly) form of power generation am we have. Isn’t it?
    - ncmncm 5y ago
      On Earth's surface? No. But various forms make sense elsewhere.
  - ncmncm 5y ago
    A smallish chunk of Strontium-90 would safely power quite a lot of moonbase for years, as the Soviets did their remote lighthouses. Strontium-90 is the ideal radionucleide; emitting negligible gamma rays or neutrons, it just sits producing heat. For power in the cloudtops of Venus, Titan, Saturn, Uranus, or Neptune, a full-scale nuclear reactor is as simple as a naked atomic pile hanging near the bottom of a big fabric tube with a wind turbine at the top, supported by a balloon. All the radiative output goes into heating the air around the pile, which rises and drives the wind turbine, which is the only moving part. On the gas giants, it would have to be supported by a hot-air balloon, because the atmosphere is hydrogen. On all four planets, surprisingly, gravity is very close to Earth-normal. (On Titan it is rather less.) Orbital velocity at the gas giants is much higher, though, so as comfortable as it might be there, it's hard to get home from them.
sfifs 5y ago
Personally, I think the most viable long term option would be to build solar farms with 120 degrees separation on the moon's circumference so you'd always have a fairly constant amount of solar power generation & run a HVDC grid. From what I can make out, a 1000 Amps capable Aluminum Composite core power cable seems to weigh about 500kg per km [1](I may be mistaken here, happy to be corrected). Moon's circumference is about 10000 km & so you'd need about 7000km of cabling or about 3500 tons. That's only about 20-40 Starship trips to transport the cables itself. Maybe with some minimal cladding (no rain/ice etc on moon), it could possibly even be laid or buried on the ground vs. requiring pylons. Once the solar panels are installed, there's little maintenance needed compared to earth (dust) and you could progressively add over time. [1] https://multimedia.3m.com/mws/media/480556O/3mtm-accr-technical-summary-metric-units.pdf?&fn=ACCRSpecSheet_8002800_DMR.pdf https://multimedia.3m.com/mws/media/480556O/3mtm-accr-techni...
- ramshanker 5y ago
  There must be a redundancy of minimum 2 independent cables though. Can’t risk losing power with any single fault event.
  - kwhitefoot 5y ago
    Just add another 3000 km of cable to complete the ring main then every point is supplied from both directions.
- politician 5y ago
  The cable could be manufactured from the Aluminum in the Lunar regolith which could simplify the logistics.
  - jfk13 5y ago
    Although shipping the cable-manufacturing plant out there might not be entirely trivial either.
    - 5y ago
TheOtherHobbes 5y ago
Apparently McMurdo Station needs 7000 tons of assorted supplies each year. Assuming Moon Base runs on a similar scale, that's an initial annual budget of $7bn just for the shipping. This assumes air and water are solved problems and don't need to be shipped. Note that oxygen != air. 100% oxygen atmospheres are not a good idea for extended stays. Nitrogen is not common on the Moon. Nor is carbon (for filtering or other organic applications.) It's not easy to imagine a lunar base generating >$7bn of returns every year. Apart from space tourism, there isn't a whole lot you can do/build/sell on a moon base that has more value on Earth than it would cost to transport back here. Of course you could argue Science, and that's fair enough. But literally all the commercial arguments I've seen have been "Something will no doubt appear" - which is possibly not going to win over rational investors.
- sandworm101 5y ago
  Retirement homes in the lower gravity? And there is the helium-3 fusion dream. That's the purpose of so many recent scifi moonbases.
  - medstrom 5y ago
    70 wealthy retirees, each paying $100M annually.
    - sandworm101 5y ago
      I assume that catering to those 70 Uber wealthy might increase cargo needs slightly. But it would cut down on family visits. The kids might pay to have grandpa sent to the moon.
    - nsonha 5y ago
      Let's coerce them into spending that money, in fact what do old people need that much for, let's seize it for science
    - sonograph 5y ago
      The market for retirees who are willing to pay $100M annually to live in a pressurized bubble on the moon is maybe one or two, for only one annum
alphydan 5y ago
for those interested, this Austin startup is hiring and building potential lunar bases: https://www.iconbuild.com/technology/space https://www.iconbuild.com/technology/space
aerophilic 5y ago
The idea I have always liked, though have never done the numbers on, is a giant “heat pipe” that would circle the moon. You could put it on any latitude you want, but you effectively take advantage of the temperature gradient to continuously flow a gas/liquid around the moon. That in turn turns turbines attached wherever you need the power.
zardo 5y ago
With 1/6 g, no wind, and no quakes, I'm not sure you can rule out building a 3km tall tower without actually doing a design study.
- llukas 5y ago
  https://en.wikipedia.org/wiki/Quake_(natural_phenomenon)#Moonquake https://en.wikipedia.org/wiki/Quake_(natural_phenomenon)#Moo...
  - inglor_cz 5y ago
    Also, extreme temperature changes. At least compared to Earth.
javajosh 5y ago
It's funny, I never thought of electricity as being a big issue for a moonbase. There are so many ways to store potential energy - you could, for example, put a bunch of moon rock/dust on a platform and run electric motors to raise it for 14 days, and then, during the lunar night, allow the platform to lower and generate electricity. But the remarkable 300 deg temp swing is a dream for power generation, although the OP is right that you'd need a medium (e.g. lots of water) to harness it as a carnot engine. Still, fun to think about since it's a hard, but not unsolvable problem.
syrrim 5y ago
>Unfortunately, it turns out that the minimum altitude necessary to avoid any shading is 2750 m, rather taller than any structure ever built on Earth. Well, you wouldn't be building it on earth. The gravity on the moon is 1/6 as strong, which I understand means it could be 6x as tall as anything on earth. Granted, this would still be massive, but closer to reasonable. >there are numerous places on the surface of the Moon, including close to polar regions, that are always in view of Earth. As I recall, the moon is tidally locked - half of it is always visible to the earth, the other half never is. Is he just qualifying that the poles are the exception? >Microwave antennas positioned here could receive power beamed up from the surface of the Earth from one of at least three stations such that one is always in view. Why based on earth? This means you have to deal with earth's atmosphere, which creates other problems. My suggestion would be to put satelites at the moon-earth lagrange points, and have them beam power around. Knowing nothing about the analysis of these things, this would probably lead to a simpler array. You could also probably eliminate the proliferation concern this way, eg by putting it at the L2 point.
deleted 5y ago
[deleted]
credit_guy 5y ago
The answer is simple: Alice [1]. ALICE is a rocket propellant made of aluminum and water. Both are available on the surface of the moon. Just make it using solar panels where the sun shines, and ferry it around using lunar rovers. If it can be used to propel rockets, it can be used to power turbines for electrical generators. And if people don't like old-fashined turbine-based dynamos, then, why not go for Alcoa's aluminum-based battery [2] ? The lunar regolith (dirt) contains plenty of oxygen and aluminum [3]. [1] https://en.wikipedia.org/wiki/ALICE_(propellant) https://en.wikipedia.org/wiki/ALICE_(propellant) [2] https://www.car-engineer.com/alcoa-phinergy-develop-commercialize-batteries-run-air-aluminum/ https://www.car-engineer.com/alcoa-phinergy-develop-commerci... [3] https://sites.wustl.edu/meteoritesite/items/the-chemical-composition-of-lunar-soil/ https://sites.wustl.edu/meteoritesite/items/the-chemical-com...
- Clewza313 5y ago
  This may be feasible as a long term solution, but how do you bootstrap the energy-intensive process of extracting and purifying aluminum in the first place?
  - credit_guy 5y ago
    You can bring let's say 100 tons of aluminum from Earth. At an energy density of 1.3 MWh/ton [1], you'd have 130 MWh of storage. And since there are 336 hours in the lunar night of 14 days, that corresponds to a power capacity of about 0.4 MW, which should be fairly decent for the bootstrap period. [1]https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery [1]
etaioinshrdlu 5y ago
Energy storage by lifting and lowering heavy objects might be more appealing than batteries. (Similar to this:https://www.power-technology.com/features/gravity-based-storage/ https://www.power-technology.com/features/gravity-based-stor...) One motor can lift a very large number of heavy blocks, and the mass of the blocks does not need to be sent from earth.
- nanomonkey 5y ago
  Sadly the moon's gravity is 1/6th of the earth's, so each block would have to be six times the mass, or you would have to lift it six times as high to store the same amount of energy.
marsven_422 5y ago
Nuclear, problem solved
JoeAltmaier 5y ago
Orbital solar collectors? Never in shade; no need to build a tower. Losses low because no atmosphere.

176 points by mercutio2 5y ago

the only answer is nuclear, simply because of energy density required for space applications. the creators of the original solid-core Krusty/Kilopower reactor are trying to commercialize the tech, I hope they have enough funding (@sama, I hope this is on your radar) https://www.spacenukes.com/ https://www.spacenukes.com/ This is the first fundamentally new reactor actually built and tested by NASA in more than 50 years (vs. countless paper designs) https://www.nasa.gov/mission_pages/tdm/fission-surface-power/index.html https://www.nasa.gov/mission_pages/tdm/fission-surface-power... EDIT: I highly recommend watching the presentation by David Poston "Space Nuclear Power for Mars" https://www.youtube.com/watch?v=luQfEYs2L0w https://www.youtube.com/watch?v=luQfEYs2L0w

baybal2 5y ago
I don't see battery storage as a problem for the first outpost, but yes, kilopower reactors were made exactly for this. Another option for early missions is just to limit them to 14 days. Heating of the base can be achieved by preheating the regolith deep beneath the surface. With regolith density we know, it should be well feasible. Thermal insulation can be made very efficient in space because there is no atmosphere. I see a nuclear/rtg base power for life support, and solar powered regolith smelting following the 14 day cycle.
- Robotbeat 5y ago
  That’s pretty reasonable. Particularly since nuclear (fission or radioisotope) produces a lot more heat than electricity (thermal to electrical conversion efficiency is just 23% for Kilopower and 3-9% for RTGs), so using it for base heating during the night is a much better argument. And even some solar powered rovers like Spirit and Opportunity used small radioisotope heat sources to stay warm.
Robotbeat 5y ago
“The answer is nuclear” is repeated often but often is an innumerate answer. Kilopower for most uses in the inner solar system performs considerably worse than solar. The power to weight ratio of Kilopower is about 6-7W/kg, no better than old time RTGs. UltraFlex solar panels do about 150W/kg near 1AU. Nuclear in the lunar case may be useful for base power due to the long lunar night which makes storage pretty heavy, but nuclear is actually usually WORSE performance than solar, producing much less power for the same mass. It’s only in the outer solar system around Jupiter or in niche cases like lunar night where nuclear has a solid lead on solar. Otherwise it’s similar or worse, besides being a lot more expensive. ~$100 million for 10kWe Kilopower.
- andyxor 5y ago
  i think you are missing the point of Kilopower, it was to build a working micro reactor prototype on realistic timeframe and actually ship it, they have designed the extension of this to MW scale where energy density is order of magnitude better. Nuclear scales better than any other source of energy. How many sq feet of solar panels do you need for 1, 10, 100, 1000, 10000 MWe, now translate it to lbs and $$$ cost (including shipping to the moon or mars base), also consider dust and lunar night conditions affecting solar use. if you look at scaling it vs. weight and cost (including maintenance and replacement panels over 20-30 years), solar is no competitor to nuclear.
  - Robotbeat 5y ago
    No, the larger nuclear power plants (50kWe) NASA has developed to reasonable TRL are still around the same power to weight ratio. Nuclear, in addition to everything else like the dynamo and the reactor itself, requires heavy radiators. Also, Kilopower has a SHORTER lifespan of about 15 years whereas solar can last 30-50 years (solar degradation is much slower than is often claimed, at least when we’ll engineered and in the absence of high humidity) as there’s no moving parts and nothing to refuel. Remember, terrestrial nuclear reactors are regularly refueled (annually?) and maintained. The traditional argument has always been that nuclear scales better than solar, but usually such comparisons are looking at sandbagged, outdated solar panels and very low-TRL nuclear designs relying on super high rejection temperatures (ie unrealistic) or shorter lifespans. I’m not anti-nuclear by any stretch, and I fully support increased funding and deployment of nuclear power, but I think there has been a lot of hand waving by some nuclear advocates. If you look at actually achievable, near term nuclear designs, none of them perform anywhere near as good as solar does in orbit near 1AU, and it’s not even close. It’s surface applications or outer solar system where nuclear has a chance against solar. Outside of those cases, solar is much more powerful for a given weight (meaning cheaper to transport) plus being far cheaper to build and not requiring special launch vehicle risk mitigations (currently, the only nuclear-rated launch vehicle is Atlas V… and every nuclear launch must be approved by the executive branch). (A human Mars base may benefit from a mix of power sources for resiliency purposes.)
shkkmo 5y ago
On the moon, Nuclear has basically the opposite problem of solar: Long, hot days mean that nuclear power generation is hard to cool during the lunar day. This means that nuclear for the moon is basically directly competing with batteries and other storage solutions in terms of weight/risk/difficulty.

go_elmo 5y ago

Looking forward for the re-boost of nuclear space-technology so many scientific opportunities!

papito 5y ago

This doesn't even mention Helium-3? Come on.

ncmncm 5y ago
Lunar Helium-3 is a mirage. There is no plausible scenario where trying to gather lunar He-3 turns out well.

h2odragon 5y ago

dont miss the bit on "remotely beamed microwave power." "silly idea" it may be but now i want a mega-maser as described for my own sporting purposes.

hereforphone 5y ago
Do they expect to outdo the sun?
- h2odragon 5y ago
  In one very specific frequency band, at one comparatively small place, yes. by a large amount. Ocean vs firehose. Or, better: In the same way every "daytime headlight" you see is outdoing the sun.
  - hereforphone 5y ago
    Which 'frequency band'? https://www.researchgate.net/figure/Spectral-power-density-of-solar-radiation-5_fig1_268822609 https://www.researchgate.net/figure/Spectral-power-density-o...
    - rrss 5y ago
      microwave
      - hereforphone 5y ago
        Brilliant answer
    - h2odragon 5y ago
      > Achieving a beam that narrow (1/2000000 rad) from the Earth would require a phased array spaced out over a much larger area, at least 200 km at 5 Ghz (6cm). I doubt they'd want a very large band but in microwave work I dunno what counts as "large". and i'm a little afraid to go look deeper into this because i'll wind up tearing up junkyard microwave ovens and building something i shouldn't.

mschuster91 5y ago

I wonder... we used to use electrically heated stone as storage medium for heating homes, until it became uneconomical due to energy price hikes. A lunar base could electrically heat up a lot of easily mined rock and use that to store enough heat to keep the base warm enough?

bbojan 5y ago
Yes, but that's not an issue here. Life support would require a lot of electrical energy, not heat.
- mschuster91 5y ago
  What do you need for basic human life support? Light, oxygen generation/CO2 removal, water, and electricity for vehicles and work appliances. Oxygen and water can be stored in tanks sufficient enough to ride out the 14 days dark cycle, LED lighting is extremely efficient (especially if everything is under 9m of moon soil, so no light can escape useless to space), the only thing that may be a problem is CO2 removal - no idea how much energy that uses.
  - gpm 5y ago
    I think CO2 depends heavily on what you're doing with it. You filter CO2 out of the atmopshere using zeolite beds at relatively low temperature/high pressure, you then recharge those by venting the beds at relatively high temperature/low pressure. If you're venting the CO2 to space (they do on the ISS), I don't have numbers/proof to back this up but you probably don't need much energy at all. You just pass air through the absorbing bed at ~1ATM (i.e. with a fan), and a heat exchanger from the venting bed to the absorbing bed might even be enough to keep the temperatures in the right range. If you're capturing the CO2 afterwards however, you probably need some more energy-expensive machinery. Again, I don't have numbers, but you're definitely talking about running a compressor to force the venting CO2 into a tank now, and you might want to compress the absorption side as well to get a bigger pressure gradient. The only real use of that captured CO2 is to recycle it into something useful (e.g. O2 and CH4 using the sabatier reaction), and that reaction is going to be endothermic, but you can probably just store the CO2 until you have sunlight and do it then.

unchocked 5y ago

I find it odd that the author dismisses hydrogen storage largely based on the requirement to mine water for electrolysis and then goes on to propose using ~12,000 tonnes of water for thermal energy storage.

baybal2 5y ago
Storing water does not require pressure vessels, nor cryogenic coolers.
- errantspark 5y ago
  It pretty definitely requires pressure vessels if you care about it's phase.
  - natosaichek 5y ago
    Well it requires a closed container that maybe has to take a few psi of water pressure. It doesn't require anything that can tolerate thousands of psi like hydrogen does.
    - errantspark 5y ago
      Oh for sure the storage problem is much much more difficult to solve wrt hydrogen than water, I was just being pedantic.
    - kolinko 5y ago
      You can store hydrogen in lower pressures if you don’t care about the amount of space it takes.
      - credit_guy 5y ago
        That's a brilliant idea. You could store the hydrogen in some big balloons. There's no buoyancy on the Moon, so you don't need to anchor these balloons. You need to cover them with a dome to protect them from micrometeorites, but when you establish a Moon colony, building domes is the name of the game. At normal (on Earth) room temperature and pressure, a balloon with a radius of 10m holds about 60 kg of hydrogen. I did some back of the envelope calculations, and that would be enough to provide about 2 kW of power for the length of the lunar night (14 days).

Diggsey 5y ago

How about two/three sites around the Shackleton crater which beam power back and forth wirelessly across the crater as each site goes in and out of sunlight?

edgyquant 5y ago
This is a sexy idea. I don’t know if it would work, but it would be fun to work on
ncmncm 5y ago
Cabling would be the thing. Shackleton Crater might make an awesome radio telescope.
- ncmncm 5y ago
  ... or even better, infrared telescope. (Both, really, at once.) With the mirrors separated from the focus by miles, they could be simple optically flat surfaces, as many as you like; and so far apart, the resolution would be unmatchable. It would probably be most useful for deep-field imaging, because to can't point it; you rely on it happening to point at something interesting, which likely means stars in galaxies very far away.
seg_lol 5y ago
From a linked research article on the main site, they had a compelling plan bounce energy around with mirrors so you don't have reconversion losses. Tracking mirrors and solar panels. The light from the sun is highly collimated.
- Diggsey 5y ago
  Interesting, but surely the last thing you want is complex mechanical systems involved that will quickly wear out due to lunar regolith, or having to transport large mirrors to the moon? Sure you get losses from wireless transmission, but you can always just add more solar panels, as they're cheap, lightweight and compact. You only need a small amount of power to keep things going during the 14 days of darkness, so you can avoid transfer losses by doing the intensive stuff during the 14 days in the sun.

state_less 5y ago

I’d imagine they’ll need to do a number of electrochemical reactions to make oxygen to breathe and fuel to burn, etc... Use an oversized solar array and store the chemical products in tanks. Batteries are chemical stores too, no? Anyhow, not sure of the efficiency of all these reactions, but more panels could help until further reaction improvements can be made.

Diggsey 5y ago
The article does consider that option via splitting and storage of water, and then recombination via hydrogen fuel cells. According to the article the mass of the storage vessels needed to store 2 weeks of pressurized hydrogen and oxygen are comparable with the mass of batteries you'd need, although I haven't done the calculations myself... Intuitively I would expect this to be more efficient than batteries though.
- gpm 5y ago
  I think the point here is rather that power load at night can be much lower than power load during the day, if most of the energy is going to optional processes like making oxygen and/or rocket fuel.
- ncmncm 5y ago
  If you are storing gases at the lunar pole, liquid is the right form. Then the tanks are very light and cheap. Liquifying gases is very easy there.

nkingsy 5y ago

How many starships full of copper would be required to run a hvdc line between enough points to get constant coverage?

baybal2 5y ago
Moon is 10% aluminium, with that constrain, I doubt copper will see much use for long range transmission.
- voakbasda 5y ago
  Mining and refining aluminum takes a huge amount of power, so you’re back to hauling tons of wire to build the initial infrastructure. Mining is definitely the way to go after that bootstrap stage, but this question remains: is this the best bootstrap plan?
  - gpm 5y ago
    But one of the key observations from this article is that we won't be power constrained, we will be constrained by consistent power, since power at night costs far, far, more than power during the day. If we can ship some extra solar panels up and refine aluminum during the day, to reduce the cost of power at night, it seems likely to be entirely worth it.
  - inglor_cz 5y ago
    You have a shitton of solar power at your disposal during the lunar day. Lunar surface is raked by the full solar constant of power, no atmosphere = no attenuation. That is quite a sizzle. So you can smelt a lot of aluminium during the fortnight when the sun is up. And build a web of wires around the entire Moon so that during the cold and dark lunar night you can get power from the other side of the Moon.
dredmorbius 5y ago
Direct transmission (e.g., microwave beamed power) might be a more viable alternative. You'd need high towers, and lots of them (smaller radius, nearer horizon), but wouldn't have the mass budget of running wire.

gpm 5y ago

I'm a fan of this comment: https://caseyhandmer.wordpress.com/2021/04/25/powering-the-lunar-base/#comment-5194 https://caseyhandmer.wordpress.com/2021/04/25/powering-the-l... TL;DR - Just don't be there during long winter nights.

Gatsky 5y ago
Agreed, it would be quite an operational hazard and probably an unethical experiment to leave astronauts on the moon for long periods. Factoring in appropriate safety margins for equipment, supplies, physiology and rescue flights, they could only stay there a few months at a time in any case.

fnord77 5y ago

another Musk fanboi, redoing the speculative work that NASA did in the 70s and then claiming credit for it.

ttul 5y ago

So, nuclear then.

ncphil 5y ago
Yeah. Nuclear may not make sense here on Earth -- even Antarctica -- where the environmental and human health consequences are practically unavoidable (especially when implemented by the lowest bidder), but space outside of LEO is another matter. NASA is in fact looking at it. https://cen.acs.org/energy/nuclear-power/NASA-thinks-nuclear-reactors-supply/98/i19 https://cen.acs.org/energy/nuclear-power/NASA-thinks-nuclear.... Although the idea of migrating researchers to a sunlit base when night falls at their primary base has potential, it's probably going to be more practical to stand up a whopping big RTG or full-on fission reactor a distance off from the habitats. Space borne fission plants are going to be necessary anyway if we're ever going to send people to the outer solar system (Jupiter, Saturn, Uranus, Neptune). We might as well learn how to make them work on the Moon ("It's a damned research project!").
- devoutsalsa 5y ago
  Nuclear is basic the safest (and climate change friendly) form of power generation am we have. Isn’t it?
  - ncmncm 5y ago
    On Earth's surface? No. But various forms make sense elsewhere.
- ncmncm 5y ago
  A smallish chunk of Strontium-90 would safely power quite a lot of moonbase for years, as the Soviets did their remote lighthouses. Strontium-90 is the ideal radionucleide; emitting negligible gamma rays or neutrons, it just sits producing heat. For power in the cloudtops of Venus, Titan, Saturn, Uranus, or Neptune, a full-scale nuclear reactor is as simple as a naked atomic pile hanging near the bottom of a big fabric tube with a wind turbine at the top, supported by a balloon. All the radiative output goes into heating the air around the pile, which rises and drives the wind turbine, which is the only moving part. On the gas giants, it would have to be supported by a hot-air balloon, because the atmosphere is hydrogen. On all four planets, surprisingly, gravity is very close to Earth-normal. (On Titan it is rather less.) Orbital velocity at the gas giants is much higher, though, so as comfortable as it might be there, it's hard to get home from them.

sfifs 5y ago

Personally, I think the most viable long term option would be to build solar farms with 120 degrees separation on the moon's circumference so you'd always have a fairly constant amount of solar power generation & run a HVDC grid. From what I can make out, a 1000 Amps capable Aluminum Composite core power cable seems to weigh about 500kg per km [1](I may be mistaken here, happy to be corrected). Moon's circumference is about 10000 km & so you'd need about 7000km of cabling or about 3500 tons. That's only about 20-40 Starship trips to transport the cables itself. Maybe with some minimal cladding (no rain/ice etc on moon), it could possibly even be laid or buried on the ground vs. requiring pylons. Once the solar panels are installed, there's little maintenance needed compared to earth (dust) and you could progressively add over time. [1] https://multimedia.3m.com/mws/media/480556O/3mtm-accr-technical-summary-metric-units.pdf?&fn=ACCRSpecSheet_8002800_DMR.pdf https://multimedia.3m.com/mws/media/480556O/3mtm-accr-techni...

ramshanker 5y ago
There must be a redundancy of minimum 2 independent cables though. Can’t risk losing power with any single fault event.
- kwhitefoot 5y ago
  Just add another 3000 km of cable to complete the ring main then every point is supplied from both directions.
politician 5y ago
The cable could be manufactured from the Aluminum in the Lunar regolith which could simplify the logistics.
- jfk13 5y ago
  Although shipping the cable-manufacturing plant out there might not be entirely trivial either.
  - 5y ago

TheOtherHobbes 5y ago

Apparently McMurdo Station needs 7000 tons of assorted supplies each year. Assuming Moon Base runs on a similar scale, that's an initial annual budget of $7bn just for the shipping. This assumes air and water are solved problems and don't need to be shipped. Note that oxygen != air. 100% oxygen atmospheres are not a good idea for extended stays. Nitrogen is not common on the Moon. Nor is carbon (for filtering or other organic applications.) It's not easy to imagine a lunar base generating >$7bn of returns every year. Apart from space tourism, there isn't a whole lot you can do/build/sell on a moon base that has more value on Earth than it would cost to transport back here. Of course you could argue Science, and that's fair enough. But literally all the commercial arguments I've seen have been "Something will no doubt appear" - which is possibly not going to win over rational investors.

sandworm101 5y ago
Retirement homes in the lower gravity? And there is the helium-3 fusion dream. That's the purpose of so many recent scifi moonbases.
- medstrom 5y ago
  70 wealthy retirees, each paying $100M annually.
  - sandworm101 5y ago
    I assume that catering to those 70 Uber wealthy might increase cargo needs slightly. But it would cut down on family visits. The kids might pay to have grandpa sent to the moon.
  - nsonha 5y ago
    Let's coerce them into spending that money, in fact what do old people need that much for, let's seize it for science
  - sonograph 5y ago
    The market for retirees who are willing to pay $100M annually to live in a pressurized bubble on the moon is maybe one or two, for only one annum

alphydan 5y ago

for those interested, this Austin startup is hiring and building potential lunar bases: https://www.iconbuild.com/technology/space https://www.iconbuild.com/technology/space

aerophilic 5y ago

The idea I have always liked, though have never done the numbers on, is a giant “heat pipe” that would circle the moon. You could put it on any latitude you want, but you effectively take advantage of the temperature gradient to continuously flow a gas/liquid around the moon. That in turn turns turbines attached wherever you need the power.

zardo 5y ago

With 1/6 g, no wind, and no quakes, I'm not sure you can rule out building a 3km tall tower without actually doing a design study.

llukas 5y ago
https://en.wikipedia.org/wiki/Quake_(natural_phenomenon)#Moonquake https://en.wikipedia.org/wiki/Quake_(natural_phenomenon)#Moo...
- inglor_cz 5y ago
  Also, extreme temperature changes. At least compared to Earth.

javajosh 5y ago

It's funny, I never thought of electricity as being a big issue for a moonbase. There are so many ways to store potential energy - you could, for example, put a bunch of moon rock/dust on a platform and run electric motors to raise it for 14 days, and then, during the lunar night, allow the platform to lower and generate electricity. But the remarkable 300 deg temp swing is a dream for power generation, although the OP is right that you'd need a medium (e.g. lots of water) to harness it as a carnot engine. Still, fun to think about since it's a hard, but not unsolvable problem.

syrrim 5y ago

>Unfortunately, it turns out that the minimum altitude necessary to avoid any shading is 2750 m, rather taller than any structure ever built on Earth. Well, you wouldn't be building it on earth. The gravity on the moon is 1/6 as strong, which I understand means it could be 6x as tall as anything on earth. Granted, this would still be massive, but closer to reasonable. >there are numerous places on the surface of the Moon, including close to polar regions, that are always in view of Earth. As I recall, the moon is tidally locked - half of it is always visible to the earth, the other half never is. Is he just qualifying that the poles are the exception? >Microwave antennas positioned here could receive power beamed up from the surface of the Earth from one of at least three stations such that one is always in view. Why based on earth? This means you have to deal with earth's atmosphere, which creates other problems. My suggestion would be to put satelites at the moon-earth lagrange points, and have them beam power around. Knowing nothing about the analysis of these things, this would probably lead to a simpler array. You could also probably eliminate the proliferation concern this way, eg by putting it at the L2 point.

deleted 5y ago

[deleted]

credit_guy 5y ago

The answer is simple: Alice [1]. ALICE is a rocket propellant made of aluminum and water. Both are available on the surface of the moon. Just make it using solar panels where the sun shines, and ferry it around using lunar rovers. If it can be used to propel rockets, it can be used to power turbines for electrical generators. And if people don't like old-fashined turbine-based dynamos, then, why not go for Alcoa's aluminum-based battery [2] ? The lunar regolith (dirt) contains plenty of oxygen and aluminum [3]. [1] https://en.wikipedia.org/wiki/ALICE_(propellant) https://en.wikipedia.org/wiki/ALICE_(propellant) [2] https://www.car-engineer.com/alcoa-phinergy-develop-commercialize-batteries-run-air-aluminum/ https://www.car-engineer.com/alcoa-phinergy-develop-commerci... [3] https://sites.wustl.edu/meteoritesite/items/the-chemical-composition-of-lunar-soil/ https://sites.wustl.edu/meteoritesite/items/the-chemical-com...

Clewza313 5y ago
This may be feasible as a long term solution, but how do you bootstrap the energy-intensive process of extracting and purifying aluminum in the first place?
- credit_guy 5y ago
  You can bring let's say 100 tons of aluminum from Earth. At an energy density of 1.3 MWh/ton [1], you'd have 130 MWh of storage. And since there are 336 hours in the lunar night of 14 days, that corresponds to a power capacity of about 0.4 MW, which should be fairly decent for the bootstrap period. [1]https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery https://en.wikipedia.org/wiki/Aluminium%E2%80%93air_battery [1]

etaioinshrdlu 5y ago

Energy storage by lifting and lowering heavy objects might be more appealing than batteries. (Similar to this:https://www.power-technology.com/features/gravity-based-storage/ https://www.power-technology.com/features/gravity-based-stor...) One motor can lift a very large number of heavy blocks, and the mass of the blocks does not need to be sent from earth.

nanomonkey 5y ago
Sadly the moon's gravity is 1/6th of the earth's, so each block would have to be six times the mass, or you would have to lift it six times as high to store the same amount of energy.

marsven_422 5y ago

Nuclear, problem solved

JoeAltmaier 5y ago

Orbital solar collectors? Never in shade; no need to build a tower. Losses low because no atmosphere.