POLL: Nuclear-Powered Moon Bases?

[TC_sc]

Actually I think they tilt the panels mainly for aerodynamic reasons. (they are in slight atmosphere to be protected from radiation). But as long as the panel is illuminated, it doesn't mind the angle.

So much is incorrect with the things you have said. For one, on ISS the angle is very important or else they wouldn't have had to conserve power when that one rotary joint malfunctioned. If there was so much atmosphere in the orbit of the ISS that it needs to worry about aerodynamics, it would have slowed and crashed a long time ago.

It is negligible with modern technology. That was 20 years ago. Like I said, get a solar powered calculator and try it. You will notice the calculator continues to work. Where I work, I have a solar powered calculator that I use mainly inside of a trailer, NO direct sunlight. Works just fine. And no it doesn't have a battery.

Very little has changed with silicon PVs in the last 20 years.

You actually need a special PV that is sensitive to IR if you want that, most of them use visible, they might be more sensitive to different frequencies depending on what technology you're using...But yes, in daylight on the Moon, there is a lot of IR. It is very hot on the surface of the Moon in daytime.

But you mention IR, that is a good point, because they are working on IR photovoltaics which will be more efficient than stirling engine, mainly for use in a RTG, but it would be useful in this context also (solar thermal).

Photo voltaics use only infra red light. They use no visible light at all. That's why PVs are so inefficient.

t is shade for the radiator (waste heat from the chain reaction) I'm worried about. You can't radiate into 200 C.

--Brian

Hence the shade for the radiators and the cool side of the sterling engine.

 

[neutrino78x]

The angle of PV in nowhere near negligible.

What you said may be true in theory, but in practice, if you to a private home using PV, they normally do not have sun trackers, and work just fine.

So, to clarify my position: it is ideal to track the Sun, but it is not strictly needed.

Where sun tracking is important is with Solar Thermal, where the angle of reflection etc. is important.

--Brian

 

[TC_sc]

The angle of PV in nowhere near negligible.

What you said may be true in theory, but in practice, if you to a private home using PV, they normally do not have sun trackers, and work just fine.

So, to clarify my position: it is ideal to track the Sun, but it is not strictly needed.

Where sun tracking is important is with Solar Thermal, where the angle of reflection etc. is important.

--Brian

You are correct that on the typical home installation PV panels are in a fixed position toward the equator. For the home they increase the number of panels to insure you get the energy you need during the day. For a moon installation all weight is critical.

 

[neutrino78x]

So much is incorrect with the things you have said. For one, on ISS the angle is very important or else they wouldn't have had to conserve power when that one rotary joint malfunctioned.

I thought they were conserving power because they didn't have all the panels up. But yes, you need the panels illuminated by the Sun, you don't want them, you know, 180 degrees away from the Sun. But it is not as if the power drops to zero if you have them 1% away from the ideal angle. By your logic, the Mars Rovers should not work because they don't track the Sun.

My point was that, while it is ideal to track the Sun, it is not strictly necessary with PV, as long as the PV panels are illuminated. Solar thermal, yes, PV, not so much.

We should also point out that a nuclear reactor, including the "portable" one we're talking about, is not a solid state device; it has control rods that moderate the reaction, and apparently also a stirling engine. Similarly, a solar thermal collector has a motor to track the sun, and it may also have a stirling engine. It is possible to use infrared optimized solar panels at the focus point, instead of a stirling engine; that's called thermophotovoltaics.

Of the several options, the only solid state power generation technology is photovoltaic panels.

If there was so much atmosphere in the orbit of the ISS that it needs to worry about aerodynamics, it would have slowed and crashed a long time ago.

Well it has to be boosted periodically due to aerodynamic drag and other factors.

"The ISS will sink a couple of kilometers per year in the future because of atmospheric drag - in its current configuration," says Larry Kos, a NASA/Marshall Space Flight Center engineer with experience in computer modeling of the space station's orbit decay. "These kinds of 'reboosts' are entirely normal. Eventually the station will have its own propulsion system to compensate for orbital decay, but until the facility has a propulsion module, it's going to need occasional lifts from the shuttle."

I believe they are planning to flight test my favorite rocket, the VASIMR, on the ISS, to compensate for the orbital decay due to aerodynamic drag and other things.

As the ISS constantly loses altitude because of slight atmospheric drag, it needs to be boosted to a higher altitude several times each year.

Very little has changed with silicon PVs in the last 20 years.

Are you kidding??? Solar panels used in space are now up to 20+ percent efficiency, that was not the case in 1979. I should have said 30 years lol. I've heard of panels with 40% efficiency etc. but those are experimental.

In 1954, the RCA Laboratories published a report on CdS photovoltaic effect. AT&T organized several demonstrations on solar cells functioning the same year. The Bell's Laboratories published the results of the solar cells operation with 4.5 % efficiency. The efficiency was increased to 6 % within a few months.

In 1959, Hoffman Electronics introduced commercially available solar cells with 10 % efficiency.

In 1985, researches of University of New South Wales in Australia have constructed a solar cell with more than 20 % efficiency.

Hence the shade for the radiators and the cool side of the sterling engine.

The point was, the radiator is quite a bit bigger than the sterling engine. All that mass and annoyance for something that only gives you 40 kW, easily done with PV. Plus, the first module of a lunar base wouldn't need nearly that much power. Maybe 2 kW. Each module would have its own solar power and its own local power storage.

My position is, and has always been, that you would not need nuclear power at an initial lunar base.

--Brian

 

[neutrino78x]

You are correct that on the typical home installation PV panels are in a fixed position toward the equator. For the home they increase the number of panels to insure you get the energy you need during the day. For a moon installation all weight is critical.

Right, those thin-film flexible solar panels are so heavy. :roll:

According to this, the SAFE reactor would be 512 kg, I think a solar panel that does 100 kW could be far less massive. The one that has actually been in space, SP-100, was over 5,000 kg.

Anyway, I'm still working on finding a good power storage system for using solar on the Moon. Thermal storage seems like one of the best methods, as I have found a source saying that you could use fuel tanks from the Altair lander for that purpose. It is still not ideal because it is not solid state. I prefer solid state because it seems like it would be more reliable.

Here are the power storage methods I know of so far:

• Batteries
• Superconducting inductor (as seen on "The Man with the Golden Gun" except with nitrogen instead of helium)
• Water (use electrolysis to separate it into H2 and O2 during the day, recombine them in a fuel cell at night for power)
• Thermal storage (have a storage tank for regolith, heat it up, it radiates the heat back at night)

The only two solid state methods are batteries and the inductor, although the inductor isn't even solid state, because you have to refrigerate it with N2. The thermal storage can, in theory, be done through a solid state method, although I think pumping the heat storage medium through pipes into a mirror to heat it and then into another tank is the usual method. The solid state method would be to store it in a box which allows infrared to enter but not leave, and use a thermophotovoltaic device to extract the power at night.

I don't think batteries are especially viable; they can't work in the cold, and they can't store that much.

None of this matters on an initial base, which would be located at an area where you have light 70+ percent of the time.

--Brian

 

[docm]

IF it works, and this is still an if, EESTOR's barium titanate ultracapacitor. Lockheed Martin'sworking with them on military and space apps. Essentially if an EESTOR were put in an electric car it could go 300 miles using a "battery" a small fraction the size of a LiION. Their effect on power generation would be a game changer.

 

[neutrino78x]

IF it works, and this is still an if, EESTOR's barium titanate ultracapacitor. Their effect on power generation would be a game changer.

Yeah I know, I didn't list it because it isn't in production yet...

btw here is another thing I found

Closed Cycle Fuel Cell

It is not Solid State, but the idea is, you would bring a small quantity of water to use with it, and it would use electrolysis to split it, then recombine it later, but it is a completely closed loop; the H2 and O2 tanks are refilled directly from water produced as a byproduct of the fuel cell. All it needs is input of electricity to do the electrolysis, and in theory, it never needs to be refilled. I don't know if they have got it to work for 14 days yet though.

Also, a user called kelseymh on instructables.com, who is apparently a high energy physicist, says the following in response to the question "why is it that my solar panel works better in natural light than from a fluorescent bulb?" and one person claimed it was because a solar panel only works on infrared, and this guy says it is wrong. Here is the quote:

What Kiteman said and more. The full solar spectrum extends far beyond what you can see (visible light), including both infrared and ultraviolet. Fluorescent lights are built and tuned to have almost entirely visible-light output (any energy that goes into radiation you can't see is effectively wasted).

The energy available to be converted by photovoltaic cells is dependent on the spectrum. Short wavelength, high frequency (violet and UV) photons carry more energy than long wavelengths. Hence, using natural light rather than "bandwidth limited" artificial lighting gives you more convertible energy input.

You can see the violet/UV effect experimentally. Get some blacklights (which have a violet/UV spectrum) and turn them on along with your regular fluorescents. You should see higher output from your photovoltaic panels under those conditions.

his profile is here.

(he is saying, it is not that they respond exclusively to a certain wavelength, but that the light source (flourescents) is emitting waves of lower power than the Sun. which is what I said...solar panels do in fact respond to visible light. A panel designed to work only with infrared is also known as a "thermophotovoltaic" device.)

--Brian

 

[Shpaget]

The primary reason why PV on houses don't track the Sun is the wind which would probably blow them away on the first stormy night.
To track the Sun you have to separate panels from the roof to give them some clearance so they can rotate, which leads to a gap in which the wing could get cough. Since they have relatively large surface they produce a lot of drag, and soon you have them flying away.

 

[docm]

The primary reason why PV on houses don't track the Sun is the wind which would probably blow them away on the first stormy night.

There are groups working on a modified Fresnel lens that redirects off axis light to up efficiency on stationary panels.

 

[TC_sc]

neutrino78x, I'm not sure about your house, but no part of my house faces the sun all of the daylight hours. Thin film seems to be the solution for home installations. Manufacturers have incorporated it into roofing materials. With these you just cover the entire roof. Since thin film are less efficient than silicon PVs, you need a lot more anyway.

There are companies out there that will install the PVs on your house and charge you a monthly fee, just as if you are still on the grid. Actually, you are still on the grid with these companies since they don't install and storage capability. You still only pay the company that installed the PVs.

I know that,s not the moon, just passing along some info on PVs. None of us here seem to have all the facts to make a decision on what's the best long term power solution for the moon. I still like the nuclear reactor for the base since that lets us test a space based reactor long term in such an environment.

If we place the outpost at the poles, if there is water there, we will need all the power we can muster. With large enough quantities of water, we can fuel space craft to explore the solar system. To discount any form of energy on the moon you are placing limits on what we can achieve. Water on the moon is still in dispute. Until we know for sure it's there, and how much, then we can't make plans on its use.

 

[MeteorWayne]

Here are the power storage methods I know of so far:

• Batteries
• Superconducting inductor (as seen on "The Man with the Golden Gun" except with nitrogen instead of helium)
• Water (use electrolysis to separate it into H2 and O2 during the day, recombine them in a fuel cell at night for power)
• Thermal storage (have a storage tank for regolith, heat it up, it radiates the heat back at night)

Another potential method is a flywheel based system. It might be easy to implement on the moon with lower gravity; perhaps supercinductor based bearings, etc.

Just throwing another idea in the pot.

 

[neutrino78x]

neutrino78x, I'm not sure about your house, but no part of my house faces the sun all of the daylight hours.

I don't own a home, I did live in a house powered by solar energy for a few months. Here in California, I think most suburban homes are exposed to sunlight most of the day. Again, the angle was not critical at that house; from about 8 AM to about 6 PM, they had full power on the solar panels, which were located on the roof and did not have tracking systems (fully solid state). It was just a normal California suburban home, there was nothing special about the shape of the roof or the location. Most residential solar installations do not have tracking, and have no issues with the angle.

You can be entirely off-grid by using batteries.

I still like the nuclear reactor for the base since that lets us test a space based reactor long term in such an environment.

We should only test nuclear things on robots etc., if humans are interacting with it, it should be a device known to work reliably.

If we place the outpost at the poles, if there is water there, we will need all the power we can muster.

A primary reason for locating the base at the pole (Shackleton crater) is that it is exposed to sunlight 70+ percent of the time; it is not subject to the 14 day night. Hence, no need for a nuclear reactor, because sunlight is abundant. You can extract all the energy you could want from the (nearly) eternal sunshine.

To discount any form of energy on the moon you are placing limits on what we can achieve.

Like I said, In Situ Resource Utilization. Living Off the Land.

Sunlight is an abundant resource in earth orbit and on the Moon, especially at the poles, where there are areas not subject to the 14 day night. On Mars, there is also wind and possibly geothermal.

--Brian

 

[TC_sc]

neutrino78x, you must have had a flat roof, which is really rare where I live.

We can keep going back and forth on the solar thing since you seem to think angle doesn't matter.

Wind power on Mars seems to be a bit wasteful of resources. Geothermal means we have to find volcanic activity and then have to dig to get it. That's a huge waste of resources.

When we get to Mars and have only solar panels, lets hope our crew doesn't get caught up in a month long wind storm. Our crews will need power that is reliable and they know will be there the next day.

Back to the moon for a moment. For now we have no evidence there is water on the moon. We just know there are concentrations of hydrogen atoms. With current data, nuclear is the only long term solution for lunar bases.

The only way to truly test anything is in real world applications. You can test something to death in a lab and will still learn things in real world applications.

I guess we should have only robots on ISS since thats just one huge testbed?

 

[neutrino78x]

neutrino78x, you must have had a flat roof, which is really rare where I live.

No, they had an angled roof like many homes in california. It is a myth that you need trackers for solar power. Solar thermal, yes, not so much with PV. In theory, it would be ideal, if you want to get every last watt of theoretical capacity out of your array, but in practice, people use PV without trackers every day and it works just fine. What exactly are you thinking, they only get 20 watts of power from the PV unless trackers are used? If that is what you are saying, you are grossly incorrect. They typically got 20+ kW daily out of the PV in summer, 15+ kW in winter. This was a small system for a 5 bedroom, 2 story house. The only thing that really blocked it was fog. Solar panels usually do not work only on specific frequencies, unless you design them that way, as in thermophotovoltaics, which, btw, is something they are working on in connection with nuclear power. It would be a solid state method of getting power from the heat. But normally PV prefers broadband illumination, as that high energy physicist said, the one whom I quoted.

PV is a great source of power in California and on the Moon.

Wind power on Mars seems to be a bit wasteful of resources.

Do you realize how fast the wind blows on Mars? Wind is already considered a very efficient green energy source on Earth, on Mars it is even better.

Geothermal means we have to find volcanic activity and then have to dig to get it. That's a huge waste of resources.

Well, Dr. Robert Zubrin, who has a doctorate in nuclear physics, says in his book The Case for Mars, that while he would put a space nuke -- 100 kW -- for the initial mission, if we do find geothermal power on Mars, it would be superior, because it is much easier to build the parts on Mars and it is a natural source of heat. I do not agree with him that a nuke would be needed initially, but I do agree with him on geothermal. Nordic countries that have abundant geothermal don't use nuclear, they use the geothermal. Why accept the difficulties and dangers of nuclear when you have an abundant (more) green power source? Living off the land...use the most abundant local power supply, instead of having to take one with you.

I agree that in general, digging is a waste of resources. But with geothermal there would be a big payoff to it.

Back to the moon for a moment. For now we have no evidence there is water on the moon. We just know there are concentrations of hydrogen atoms. With current data, nuclear is the only long term solution for lunar bases.

All you need to do the fuel cell energy storage is hydrogen atoms and oxygen atoms, both of which are known to exist on the Moon. Besides which, that is merely one of many energy storage systems that should be used. Multiple redundant backups. Remember, you would not need 130 kW per hour initially. By the time you did, the power storage would be expanded appropriately.

The only way to truly test anything is in real world applications. You can test something to death in a lab and will still learn things in real world applications.

Anything we put on a rocket has to be known to be able to survive reentry without becoming a dirty bomb. They tested the SNAP reactor for that before launching it, same with RTGs. I also want reactors not to meltdown on the Moon, etc., etc., etc. There are many safety issues with nuclear power which do not exist with other power sources, which is one of many reasons why I would not want it on an initial lunar mission. I am not against nuclear power, as I was on a nuclear powered submarine. But I want it done right, and I don't want to use it when it is not necessary.

--Brian

 

[MeteorWayne]

Do you realize how fast the wind blows on Mars? Wind is already considered a very efficient green energy source on Earth, on Mars it is even better.

--Brian

Do you know how thin the air is on Mars? Despite the speeds, there is not very much kinetic energy available in the stream....

 

[Boris_Badenov]

Do you realize how fast the wind blows on Mars? Wind is already considered a very efficient green energy source on Earth, on Mars it is even better.

--Brian

Do you know how thin the air is on Mars? Despite the speeds, there is not very much kinetic energy available in the stream....

Somebody (jonclarke?) ran the numbers one time & the propeller would have to so big & the generator so small that the power return would be insignificant.
Wind generators won't work on Mars until we've thickened the atmosphere substantially.

 

[neutrino78x]

Wind generators won't work on Mars until we've thickened the atmosphere substantially.

should work ok...

--Brian

 

[Shpaget]

The blades of the turbine would have to be really, really, really immune to abrasion.
Dust and sand particles hitting the rotor at 100+ km/h would quickly grind it to nothingness.

 

[TC_sc]

We move all that mass to Mars and then sit around hoping there is a dust storm so we can use it. Even then it would have to be a super storm and a windmill with massive blades. All because some people hate nuclear power. If you have a year long wind storm you had better have a lot of hydrogen for the fuel cells if you go with solar alone. I don't see NASA spending the money to put windmills on Mars.

Wind generators won't work on Mars until we've thickened the atmosphere substantially.

should work ok...

--Brian

 

[TimeDog]

i voted nuclear. its the best option we have at the moment. just think of all the repair costs for busted solar panels too.

 

[neutrino78x]

We move all that mass to Mars and then sit around hoping there is a dust storm so we can use it.

No, any massive windmills would be built on Mars. You might want a small integrated windmill on the landing pod to take advantage of the powerful winds during the windstorms, but windmills intended to generate power on a regular basis would be built on the planet.

That's the whole theme of those of us who don't see a need for nuclear on the Moon: living off the land.

You can wait until you have battlestar gallactica or the USS Enterprise NCC-1701 before you go to Mars, or you can go with today's technology and live off the land.

All because some people hate nuclear power.

ok...I clearly do not "hate" nuclear power.

The space nukes they have/are being considered right now are only 100 kW. The ISS proves that this amount of power can be delivered with PV. If we had a nuke the same size that delivered 20 MW, it would be more interesting to me. As it stands, solar can do the same job, without the added dangers and hassle of nuclear power. Granted, solar is harder on Mars than the Moon, but it can still be done. Surely, on the Moon, where the solar output is twice that on Mars, it should be more than sufficient, especially since you can eventually manufacture the PV panels and/or mirrors on the Moon. You could manufacture PV panels and/or mirrors on Mars also.

I think the niche for nuclear in space would be the spacecraft themselves, if we want to go outside the asteroid belt in a reasonable time with reliable power supplies. Although we should note that NASA apparently dropped the Jupiter Icey Moons Orbiter in part because of hesitation as far as the reliability of the space reactor designs.

If you have a year long wind storm you had better have a lot of hydrogen for the fuel cells if you go with solar alone. I don't see NASA spending the money to put windmills on Mars.

I don't think NASA would put anything other than solar on Mars for the initial missions, nor is anything else needed, in my opinion.

 

[neutrino78x]

The blades of the turbine would have to be really, really, really immune to abrasion.
Dust and sand particles hitting the rotor at 100+ km/h would quickly grind it to nothingness.

The NASA guy quoted in the article didn't seem too concerned. Robert Zubrin in The Case for Mars says you would want to find the ideal altitude on Mars where they are most effective, and it would probably be easier to make large windmills on Mars than Earth, given lower gravity. I know some have proposed floating windmills on Earth.