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Re:Blue Origin manufactured solar cell prototype from lunar ... by schiffern on Tuesday February 14, 2023 @06:01PM (#34797464)
>The bigger problem is how practical is it to use PV at all on much of the moon.

I think part of the solution will involve using "regular stuff" (which can be sourced from lunar atoms) like batteries.

Don't use lithium batteries to continuously power an oxygen generator. Instead, have an enlarged oxygen generator and store half the flow for use at night.

Don't use lithium batteries to power a heater at night, instead "pre-charge" heat in a dirt thermal mass during the day.

Don't use lithium batteries to power a continuous CO2 scrubber, instead use a liquid amine scrubber and recharge the fluid tanks during the day.

Etc etc

Obviously you need to do in-depth tradeoff math for each case, but my napkins say "the system is the battery" wins in many cases.

Re:Blue Origin manufactured solar cell prototype from lunar ... by paranoidrobot on Tuesday February 14, 2023 @07:16PM (#34798226)
Lunar night being about 14 days might make that a bit more difficult for any permanent settlement.

Storing 14+ days worth of <everything> is going to mean massive amounts of storage.

Re:Blue Origin manufactured solar cell prototype from lunar ... by mlyle on Tuesday February 14, 2023 @07:26PM (#34798306)
Yup. Nuclear seems likely to be part of the solution.
Re:Blue Origin manufactured solar cell prototype from lunar ... by schiffern on Tuesday February 14, 2023 @09:28PM (#34799262)
>Storing 14+ days... is... massive

...which is why you want to be extra careful in how mass-efficiently you're storing it.

A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery. Later on, insulated tanks are vastly easier to produce from lunar materials vs batteries. These are all nice leverage multipliers.

Nuclear is a popular notion, but the real-world economics don't favor it. Effectiveness beats elegance.[0]

[0] https://spacecraft.ssl.umd.edu/akins_laws.html

Re:Blue Origin manufactured solar cell prototype from lunar ... by mlyle on Wednesday February 15, 2023 @12:44AM (#34800529)
> A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery.

Making liquid oxygen (as opposed to gaseous oxygen) is not a terribly efficient process.

Re:Blue Origin manufactured solar cell prototype from lunar ... by schiffern on Wednesday February 15, 2023 @02:03AM (#34800914)
Thanks, yes I meant to mention liquefaction but then ADD.

You have to do the trade between liquefaction and storing oxygen as a pressurized gas. Reusing a single Starship's propellant tanks, for example, at 6 bar would hold ~14 metric tons of oxygen, enabling a continuous lunar population of over 1,000 people.

The compression or liquefaction energy isn't a show-stopper necessarily, it just works into the total energy efficiency of the storage system. Compression is nice because practical isothermal compressors are now being demonstrated.[0]

Both liquefaction and compression require cooling. I do think it probably makes sense to do the thermal storage trick in reverse also, storing up a bank of "cold" at night to be used during the day. The thermal radiator panels still provide (derated) cooling in the day, but the thermal storage pool time-shifts the natural oversupply of cooling power at night.

[0] https://newatlas.com/good-thinking/carnot-centrifugal-air-co...

Re:Blue Origin manufactured solar cell prototype from lunar ... by tomrod on Tuesday February 14, 2023 @09:38PM (#34799330)
Is setting up shop at the poles feasible?
Re:Blue Origin manufactured solar cell prototype from lunar ... by AlphaSite on Wednesday February 15, 2023 @03:08AM (#34801279)
I suspect there are some great solutions to power storage on the moon, eg why not store power in molten metals/substances? The lack of an atmosphere would help massively reduce thermal loss, and as you already have a refinery much of the infrastructure for this already exists.
Re:Blue Origin manufactured solar cell prototype from lunar ... by thworp on Wednesday February 15, 2023 @05:58AM (#34802255)
> The lack of an atmosphere would help massively reduce thermal loss

Care to elaborate? As an interested layperson I always thought the major factor for losses in open air was radiation into space. As such an atmosphere's thermal mass would be benfitial, no?