Long Duration Battery?

[Zatnikitelman]

Does anyone know if there exists a battery or other non-nuclear power-supply that can provide power for about 2 weeks continuous 24/7? This is preferably rechargeable, but doesn't have to be.
I'm considering alternate solutions to certain modules in my MoonBase and would like to still have a solar module, but being compatable with a non-Orulex perfect sphere, will be in darkness for about two weeks out of every four.
Thanks,
Zat

 

[Urwumpe]

All batteries can do that, the question is just how much power.

A simple Lithium-ion battery can power a remote sensor for a few months, but only because the sensor uses as little power as possible.

For a moonbase, batteries and solar power would still be the best option alternative to nuclear reactors. High power demands would be cheaper with nuclear power, but solar power is simpler to maintain. But for two weeks of operation in darkness, you would need really large battery modules - similar to conventional submarines.

 

[n0mad23]

If you're willing to leap forward to possible tech maybe 5 years from now, you might want to check out some of the work being done with Carbon/carbon aeorgel batteries.

Lots of promise here.

 

[Andy44]

This is one of the reasons NASA is considering placing their base at the south pole, so that solar arrays placed on a hilltop will get constant sunlight.

As Urwumpe pointed out, there are several betteries that can do this job, but you'll need a very large capacity to feed a base for two straight weeks, unless everyone sits in the dark and wears heavy coats and does nothing. And you'll want a back up, too, so have some fuel cells standing by.

The batteries will also age and need to be replaced at some point, but if you're getting regular resupply, that shouldn't be an issue.

Would be nice to set up a power grid with transmission lines running fom the poles!

 

[n0mad23]

I'm hoping that someone will get the urge and build the Malapert Mountains for this very reason.

If memory serves, I think one is about a mile high and remains in sunlight nearly 90% of the time. It'd be a great place to set up an Orbiter base.

 

[Andy44]

Well, you should be able to do it with Orulex using a bitmap, though I don't know how easy it would be.

 

[Zatnikitelman]

Thanks a lot guys! This is why this forum is so great. At M6, this topic would have been given a crackpot answer about 1 hour later, then sat till the servers finally died a week later
THANKS!!!!!

 

[silent_protagonist]

A couple other options might be a combination of an electrolysis plant and fuel cell, or some large fly wheels. I don't know how efficient either is, but I think the electrolysis/fuel cell idea has been proposed for terrestrial solar plants.

The only heightmap I've been able to find of the lunar south pole annoyingly had a hole right over Shackleton and Malapert craters. Hopefully this will generate some new high-res maps sometime soon.

 

[tblaxland]

Say your base (2-3 people?) use 15kWh/day (about the same as a small house with air conditioning) then you need 210kWh or storage for two weeks plus (say) 20% contingency (assuming you have some other backup, eg, fuel cells) = 252kWh.

Based on sealed lead acid batteries (as used in diesel subs), you would have a battery weight of about 6 tonnes and a volume of about 3 cubic meters. Pretty hefty.

Lithium ion batteries (being developed for use in subs) you would have battery weight of about 1.5 tonnes and volume of about 0.9 cubic meters. Much better.

 

[Andy44]

Don't forget that the energy capacity of the batteries has to be satisfied by solar arrays in 14 days, and that means more solar arrays to provide power for the station's daily consumption. The weight of the batteries is not enough to know; you need to know the mass of the whole system, solar arrays, batteries, cables, power distribution hardware, plus whatever extra you've got for backup.

 

[Zatnikitelman]

Thanks for the great info. Yea, I figured that LIon batteries would be the way to go, that's only about 1500 Kg. Shouldn't need more than about that much in fuel to go from LEO to the moon, not counting landing and such.
My problem now is calculating the amount of power that actually is. Given the 252kWh quoted by tblaxland, and given that the ISS's arrays produce 32.8kW of power for 1326 square meters of photovoltaics, I need to figure out just how big the arrays need to be to get that 252 number. Would this just mean I need to produce 252 kW then sit on it till lightness turns to dark?

 

[n0mad23]

Don't forget that the energy capacity of the batteries has to be satisfied by solar arrays in 14 days, and that means more solar arrays to provide power for the station's daily consumption. The weight of the batteries is not enough to know; you need to know the mass of the whole system, solar arrays, batteries, cables, power distribution hardware, plus whatever extra you've got for backup.

Which is why the polar mountains are so important - more time in sunlight. I'm thinking with about 200 - 300 km of electrical cable set between solar arrays on 3 or 4 mountains in the south pole region, you might actually only need battery power for 2 or 3 days, tops!

So what do you all think? Aluminum for electrical cables, or go with calcium metal instead? Both are "fairly" abundant on the Moon.

Fiberglass (locally made) for insulation, I'd say.

 

[Andy44]

Thanks for the great info. Yea, I figured that LIon batteries would be the way to go, that's only about 1500 Kg. Shouldn't need more than about that much in fuel to go from LEO to the moon, not counting landing and such.
My problem now is calculating the amount of power that actually is. Given the 252kWh quoted by tblaxland, and given that the ISS's arrays produce 32.8kW of power for 1326 square meters of photovoltaics, I need to figure out just how big the arrays need to be to get that 252 number. Would this just mean I need to produce 252 kW then sit on it till lightness turns to dark?

Well, let's see...your 1326 m^2 solar cells produce 32kWh of energy after exactly 1 hour pointed exactly at the sun. Should be easy to do the math from there.

To nomad23: assume any cables and hardware will have to come from Earth until things at the base are set up and running, since electrical power will be one of the very first things you need before you can even think about fabricating your own stuff on site.

 

[tblaxland]

I don't think that 32kW for 1326sqm of cells is correct - this should be more like 132.6sqm.

Let's work it out this way - insolation will be about 1.5kW/sqm. Lets assume 15% efficiency for the photovoltaics (includes depreciation for age/dirt/cell damage etc). That gives an output 0.225kW/sqm which generates 0.225kWh/sqm when pointed directly at the sun for an hour. Assuming you have sun tracking panels capable of going from horizon to horizon you will need about 7sqm of solar panels to provide power to the station and charge the batteries at the same time.

My guestimate is that the weight (including tracker, electronics etc) would be in the order of 30-40kg per sqm of panel = 210kg-280kg for your requirements.

 

[Notebook]

A couple other options might be a combination of an electrolysis plant and fuel cell, or some large fly wheels. I don't know how efficient either is, but I think the electrolysis/fuel cell idea has been proposed for terrestrial solar plants.

The only heightmap I've been able to find of the lunar south pole annoyingly had a hole right over Shackleton and Malapert craters. Hopefully this will generate some new high-res maps sometime soon.

By a spooky coincedence ESA has just released some new images from SMART-1:-

http://www.esa.int/esaMI/SMART-1/SEM1S6M5NDF_0.html

N.

 

[thomasantony]

I am BIG fan of ultracapacitors. Once they can be made with large enough capacity ( in terms of energy density ) , I think there are already systems and electronics that can provide a constant voltage supply from the capacitors. In fact I did come across such a circuit on google .. though I don't have the link now . And these capacitors are supposed to have amazing temperature tolerance

 

[NukeET]

I am BIG fan of ultracapacitors. Once they can be made with large enough capacity ( in terms of energy density ) , I think there are already systems and electronics that can provide a constant voltage supply from the capacitors. In fact I did come across such a circuit on google .. though I don't have the link now . And these capacitors are supposed to have amazing temperature tolerance

Those made of aerogel, I assume?

 

[n0mad23]

Silent protagonist (and any other interested parties),

Here's a link to fairly decent south pole typographical maps:

http://www.nasa.gov/mission_pages/exploration/mmb/022708.html



specifically - a 13meg digital elevation map in .tiff format
http://www.nasa.gov/images/content/214141main_04_DEM_Lunar_SPoleRegion_300dpi.tif

lots of other good things on this page.

 

[thomasantony]

Ultracapacitors can be made from aerogels as well as carbon nanotubes or activated carbon, or some polymers .

~
Thomas