Cooling on the moon

[Trolidan7]

Basic question

Would it be possible to build a classic turbine driven
power plant on the moon?

There are likely no fossil fuels on the moon and no uncombined
oxygen.

There is however likely some uranium, if you could use some
energy to mine and purify it to build power plant cores.

Then in theory if you used energy from such material you
then might use the heat of the core to melt and reduce
metals and generate raw materials for building robots and
other materials to mine and extract more from the moon
to build with.

There is also oxygen in the moon as the oxides of metals,
so reduce the metals and you have the potential for solid
rocket fuel and oxygen to combine it with.

Now one way of reducing metals is electrolysis, and you
could use a core for heating to get higher temperatures. The
problem is stable reliable cooling.

There is no water on the moon to cool a power plant and
there is no air on the moon also.

So are classic turbine power plants on the moon impossible
due to a lack of a reliable cooling method? How much surface
area would you need to rely on radiation alone without fans or
water exposed to an external environment to cool something?

How long would it take for a kilogram or a ton of molten iron
to cool to room temperature in the shade on the moon?

Now I am guessing that Mars would be different because there
would be ice and dry ice at the poles. Is it reasonable to say
that this problem would be essentially the same on Mercury
as on the Moon except there would be greater potential for solar
energy use comparatively?

[Jan Panteltje]

On a sunny day (Tue, 22 Feb 2022 12:37:37 -0800) it happened Trolidan7
<Trol...@eternal-september.org> wrote in <sv3hij$4d3$1...@dont-email.me>:

>Basic question
>
>Would it be possible to build a classic turbine driven
>power plant on the moon?

I do not know,
but for small things like a moon station one or more RTGs would work fine
and will work for a long time without maintenance:
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

Radiate to space for cooling.

The generated heat could also be used to warm human habitats.

I do not think there is much of a technology problem'
What we need is the political will to go and colonize the universe
Endless driving around the block in an ISS is silly.

[Michael Dworetsky]

Why go to all that trouble when on the Moon you have an unlimited amount
of solar energy for half the time, after all there are no clouds (but
you would need storage batteries to get through the nights), or all the
time if you put the solar panels on the rim of a crater near one of the
poles (IIRC the equator is nearly in alignment with the ecliptic). And
there is plenty of silicon available to manufacture the panels.

Refining crustal uranium and enriching it to reactor purity needs a
pretty intensive industrial capability, and if you wanted to smelt and
refine metals from surface rocks you would only need to have a
reflecting surface to focus the sunlight on the rocks to generate a lot
of heat.

--
Mike Dworetsky

[Trolidan7]

Just doing a slight search, it looks like RTGs are good at producing a
small amount of power for an exteremely long amount of time, but may
or may not be viable for the power requirements of large scale
metallurgy or the reduction of silicon, aluminum, or iron for building
materials or other things besides propulsion requiring large amounts of
power.

It is not obvious whether a heat sink would be a problem.

I will look up fuel cells on the ISS a bit more. It might be that
solar-electrolysis would be the only realistic way to go, then again
maybe not.

[Trolidan7]

> Mike Dworetsky

A am not sure about all of the properties of amorphous non-reduced
silica, but even classic solar panels require reduction of silicon as
a non-oxide like aluminum or iron.

Solar energy is relatively diffuse and non-concentrated as a form of
energy.

There would definitely be more of it on Mercury, but like Mars, it
is about 200 times further away than the Moon at closest approach (.5 AU).

No humans to repair all the mining and metal working robots either since
they require food and air and water.

[Lou]

I’m not sure about if the technology would be possible but..
How about water? Inside a steam turbine driven by daytime heat on moon.
Which apparently goes to 260 degrees f.
Water would have to be transported to moon and that might be prohibitively
expensive, but once there not only could you use it for energy you could
also possibly drink it. Maybe even tiny portable steam turbines.

[Martin Brown]

I suspect mineable uranium ore will be effectively non-existent on the
moon. It is incredibly rare on Earth even though a relatively common
element in crustal rocks (~2ppm in most things & more in granite).

Might stand a chance of finding some on Mars though.

>>
>> Mike Dworetsky
>
> A am not sure about all of the properties of amorphous non-reduced
> silica, but even classic solar panels require reduction of silicon as
> a non-oxide like aluminum or iron.
>
> Solar energy is relatively diffuse and non-concentrated as a form of
> energy.

You can concentrate it if you try hard enough and with the moons low
gravity and no wind loading to worry about the reflectors can be fairly
lightweight. Bootstrap up to larger kit as and when more materials have
been refined. Same applied to making electricity too you can effectively
double the output of solar panels by carefully placed mirrors.

https://en.wikipedia.org/wiki/Odeillo_solar_furnace

Has the advantage for some techniques of no combustion products just
very concentrated sunlight focussed onto a crucible.

Water ice might well be the most valuable commodity on the moon - at
least if you are hoping to live there in a moonbase.

>
> There would definitely be more of it on Mercury, but like Mars, it
> is about 200 times further away than the Moon at closest approach (.5 AU).
>
> No humans to repair all the mining and metal working robots either since
> they require food and air and water.

Humans are fragile and really only worth sending to the moon or even
worse Mars iff we run into something that our robotics really cannot
handle. Autonomous probes and rovers have done pretty well recently.

--
Regards,
Martin Brown