Author Topic: Power options for a Mars settlement  (Read 145213 times)

Offline deruch

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Re: Power options for a Mars settlement
« Reply #540 on: 04/28/2018 03:58 am »
For the last few weeks I've been working on a project to simulate the electrical supply and demand for a Martian colony. I'd really appreciate any feedback people have. The simulator can be found here:

https://davedx.github.io/mars-power/

The source code is on Github.

The motivation behind this was to see what impact dust storms have on PV generation and how PV compares to nuclear (the model uses Kilopower modules here), and what kind of battery strategies could be used to try and ensure generation supply meets demand as often as possible even if a dust storm occurs.

Let me know what you think :)
Very cool.   8)

I guess in your simulation the crew landed on the shore of a previously unknown Martian lake?    :D 

Sabatier requires water but you only have that and ECLSS in your power consumption budget and no drilling/digging/refining/pumping/etc. for getting the water needed to produce CH4.  Likewise no budget for condensing CO2.  Also, besides chilling out eating potatoes, what are the members of this colony doing while they watch CH4 being produced?  Are they exploring, doing science/research, watching TV, etc?  All of these things will require significant power over and above what your model seems to have budgeted.
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Offline john smith 19

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Re: Power options for a Mars settlement
« Reply #541 on: 04/28/2018 09:53 am »
For the last few weeks I've been working on a project to simulate the electrical supply and demand for a Martian colony. I'd really appreciate any feedback people have. The simulator can be found here:

https://davedx.github.io/mars-power/

The source code is on Github.

The motivation behind this was to see what impact dust storms have on PV generation and how PV compares to nuclear (the model uses Kilopower modules here), and what kind of battery strategies could be used to try and ensure generation supply meets demand as often as possible even if a dust storm occurs.

Let me know what you think :)
Nice work.

BTW, despite what people claim about thin film solar being light weight and highly volume efficient Tesla Solar does not actually use thin film technology.

It's either single crystal Silicon or "solar tiles" which seem to be glass but I'm not sure what's on the backside as the PV element.

Neither option is AFAIK weight optimized for Mars.

And as was  pointed out in a talk by one of the SX engineers they are looking for something like 500MW for ISRU use at around 500W/m^2 (on Mars surface).
BFS. The worlds first Methane fueled FFORSC engined CFRP stainless steel structure A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structure booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline speedevil

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Re: Power options for a Mars settlement
« Reply #542 on: 04/28/2018 10:16 am »
And as was  pointed out in a talk by one of the SX engineers they are looking for something like 500MW for ISRU use at around 500W/m^2 (on Mars surface).

I think you'll find it's 500kW.

At least near-term.
1000 tons of methane combustion energy is 4*10^7J/kg*10^6 = 4*10^13J.
A year is 3*10^7s, so a megawatt is the right order of magnitude.

With off-the-shelf non thin-film monocrystalline panels, and tesla batteries, you can get 500kW average per BFS cargo mass.

At 50% efficiency doing the proper calculation leads to a couple of BFS per synod refuelling capability per BFS cargo.
In the ebay powering mars thread

You get three per synod if you can turn off the methane generation during the night.

If you are assuming your BFS are going back, and believe the $130/kg number, actual purchase price of the cells is a non-trivial component - 30%.

If you can make your solar panels twice as light, but they cost over three times as much, this is not a win.

Offline niwax

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Re: Power options for a Mars settlement
« Reply #543 on: 04/28/2018 10:58 am »
There is one relaxing factor in the initial ISRU needs: The two initial unmanned Mars missions. If they manage to carry the equipment needed for an ISRU proof of concept filling a single BFS in 2-4 years, any settlers arriving later would always have a way home and most of the fuel will have been produced when the decision is made to send humans. The mission could use enlarged onboard panels to run at a fraction of the rate necessary for regular operation and then be remodeled into a bigger fuel plant when the human workforce arrives with more solar cells.
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Offline redskyforge

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Re: Power options for a Mars settlement
« Reply #544 on: 04/28/2018 03:23 pm »
For the last few weeks I've been working on a project to simulate the electrical supply and demand for a Martian colony. I'd really appreciate any feedback people have. The simulator can be found here:

https://davedx.github.io/mars-power/

The source code is on Github.

The motivation behind this was to see what impact dust storms have on PV generation and how PV compares to nuclear (the model uses Kilopower modules here), and what kind of battery strategies could be used to try and ensure generation supply meets demand as often as possible even if a dust storm occurs.

Let me know what you think :)
Very cool.   8)

I guess in your simulation the crew landed on the shore of a previously unknown Martian lake?    :D 

Sabatier requires water but you only have that and ECLSS in your power consumption budget and no drilling/digging/refining/pumping/etc. for getting the water needed to produce CH4.  Likewise no budget for condensing CO2.  Also, besides chilling out eating potatoes, what are the members of this colony doing while they watch CH4 being produced?  Are they exploring, doing science/research, watching TV, etc?  All of these things will require significant power over and above what your model seems to have budgeted.

That's true. It's an ongoing project, if I can get what people think are realistic numbers for activities that are essential like mining water, I can easily add it to the simulation (or if someone makes a pull request that's fine too!).

Has SpaceX talked about how they plan to extract water for the Sabatier process? All I've been able to find is that Elon said they need to find landing sites where there "is water", but not in detail how to extract it (and that autonomously too, given the first mission is unmanned).

Likewise for other human activities, colony building, tunnel boring. If we can calculate realistic numbers then I can add them in.

Offline redskyforge

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Re: Power options for a Mars settlement
« Reply #545 on: 04/28/2018 03:26 pm »
And as was  pointed out in a talk by one of the SX engineers they are looking for something like 500MW for ISRU use at around 500W/m^2 (on Mars surface).

I think you'll find it's 500kW.

At least near-term.
1000 tons of methane combustion energy is 4*10^7J/kg*10^6 = 4*10^13J.
A year is 3*10^7s, so a megawatt is the right order of magnitude.

With off-the-shelf non thin-film monocrystalline panels, and tesla batteries, you can get 500kW average per BFS cargo mass.

At 50% efficiency doing the proper calculation leads to a couple of BFS per synod refuelling capability per BFS cargo.
In the ebay powering mars thread

You get three per synod if you can turn off the methane generation during the night.

If you are assuming your BFS are going back, and believe the $130/kg number, actual purchase price of the cells is a non-trivial component - 30%.

If you can make your solar panels twice as light, but they cost over three times as much, this is not a win.

That's the point of this software... it goes beyond calculations and simulates other events such as dust storms that affect the variability of PV generation. Maybe 500 kWp just isn't enough.

Offline speedevil

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Re: Power options for a Mars settlement
« Reply #546 on: 04/28/2018 03:27 pm »
That's the point of this software... it goes beyond calculations and simulates other events such as dust storms that affect the variability of PV generation. Maybe 500 kWp just isn't enough.

Maybe it's not.
But it's almost certainly not 500MWp.
(the 500kW was average)

Offline Robotbeat

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Re: Power options for a Mars settlement
« Reply #547 on: 04/28/2018 03:32 pm »
Yeah, even with a good, southerly spot with trackers, to get an average 500kW of power on Mars, you're going to need about a nameplate (i.e. Earth-side at noon) capacity of 4 Megawatts. Probably want more than that for margin and so you don't need as big of a battery or electrolysis plant.

Also, pet peave: the Sabatier Reaction doesn't need water, and is technically exothermic so it doesn't need (much) electricity, either. It just needs hydrogen and CO2. It's the production of the hydrogen by electrolysis that requires water and electricity.
« Last Edit: 04/28/2018 03:33 pm by Robotbeat »
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Offline speedevil

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Re: Power options for a Mars settlement
« Reply #548 on: 04/28/2018 04:08 pm »
Yeah, even with a good, southerly spot with trackers, to get an average 500kW of power on Mars, you're going to need about a nameplate (i.e. Earth-side at noon) capacity of 4 Megawatts. Probably want more than that for margin and so you don't need as big of a battery or electrolysis plant.
The assumption on the above thread was 200W nameplate on earth = 20Wav on Mars, or pretty much exactly 5MW.
Trackers improve things.


Offline redskyforge

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Re: Power options for a Mars settlement
« Reply #549 on: 04/29/2018 02:59 pm »
Yeah, even with a good, southerly spot with trackers, to get an average 500kW of power on Mars, you're going to need about a nameplate (i.e. Earth-side at noon) capacity of 4 Megawatts. Probably want more than that for margin and so you don't need as big of a battery or electrolysis plant.

Also, pet peave: the Sabatier Reaction doesn't need water, and is technically exothermic so it doesn't need (much) electricity, either. It just needs hydrogen and CO2. It's the production of the hydrogen by electrolysis that requires water and electricity.

Yep. I read this today, it's a great analysis of the requirements for an ISRU propellant plant: http://www.thespacereview.com/article/3479/1

It also includes an estimate for the power requirements of robotic water/ice mining, including producing purified water that can be used to break into hydrogen for the Sabatier input. Turns out the mining power requirements are quite high too: 7.5-kilowatt-hour to produce 33kg of water.

I've made an issue to add this to the simulator. :)
« Last Edit: 04/29/2018 03:00 pm by redskyforge »

Offline Elmar Moelzer

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Re: Power options for a Mars settlement
« Reply #550 on: 04/29/2018 04:48 pm »
The BFS, at least the crewed one is going to have quite large solar panels on it to provide power during the journey. I wonder if some of these could become the basis for a solar power plant on the martian surface. The 2016 BFS was supposed to carry about 200 kW worth of solar panels. I can't remember what the downsized one was supposed to have. Anyone got numbers for this?

Offline john smith 19

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Re: Power options for a Mars settlement
« Reply #551 on: 04/29/2018 04:59 pm »

Yep. I read this today, it's a great analysis of the requirements for an ISRU propellant plant: http://www.thespacereview.com/article/3479/1

It also includes an estimate for the power requirements of robotic water/ice mining, including producing purified water that can be used to break into hydrogen for the Sabatier input. Turns out the mining power requirements are quite high too: 7.5-kilowatt-hour to produce 33kg of water.
Yes. When you look at rigs to drill water wells on Earth I think they tend to run about 30Kw. The power issues is one part the bigger issue is to engineer one that runs unattended. This is a complex task in a hostile environment. Mostly, what do you do if something fails?
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Offline Robotbeat

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Re: Power options for a Mars settlement
« Reply #552 on: 04/29/2018 05:34 pm »
Yeah, even with a good, southerly spot with trackers, to get an average 500kW of power on Mars, you're going to need about a nameplate (i.e. Earth-side at noon) capacity of 4 Megawatts. Probably want more than that for margin and so you don't need as big of a battery or electrolysis plant.

Also, pet peave: the Sabatier Reaction doesn't need water, and is technically exothermic so it doesn't need (much) electricity, either. It just needs hydrogen and CO2. It's the production of the hydrogen by electrolysis that requires water and electricity.

Yep. I read this today, it's a great analysis of the requirements for an ISRU propellant plant: http://www.thespacereview.com/article/3479/1

It also includes an estimate for the power requirements of robotic water/ice mining, including producing purified water that can be used to break into hydrogen for the Sabatier input. Turns out the mining power requirements are quite high too: 7.5-kilowatt-hour to produce 33kg of water.

I've made an issue to add this to the simulator. :)
Im going to have to disagree with your characterization of 7.5kWh to produce 33kg of water being “a lot.” The chemical energy of 1kg Of split water is over 4kWh per SINGLE kilogram of water, assuming perfect efficiency. With realistic efficiency, we’re talking more like 7.5kWh per SINGLE kilogram. So electrolysis still requires about 30 times more energy than mining and purifying the water.

The energy requirements for mining and purifying the water are basically a rounding error.
« Last Edit: 04/29/2018 05:35 pm by Robotbeat »
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Offline redskyforge

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Re: Power options for a Mars settlement
« Reply #553 on: 04/29/2018 05:50 pm »
Yeah, even with a good, southerly spot with trackers, to get an average 500kW of power on Mars, you're going to need about a nameplate (i.e. Earth-side at noon) capacity of 4 Megawatts. Probably want more than that for margin and so you don't need as big of a battery or electrolysis plant.

Also, pet peave: the Sabatier Reaction doesn't need water, and is technically exothermic so it doesn't need (much) electricity, either. It just needs hydrogen and CO2. It's the production of the hydrogen by electrolysis that requires water and electricity.

Yep. I read this today, it's a great analysis of the requirements for an ISRU propellant plant: http://www.thespacereview.com/article/3479/1

It also includes an estimate for the power requirements of robotic water/ice mining, including producing purified water that can be used to break into hydrogen for the Sabatier input. Turns out the mining power requirements are quite high too: 7.5-kilowatt-hour to produce 33kg of water.

I've made an issue to add this to the simulator. :)
Im going to have to disagree with your characterization of 7.5kWh to produce 33kg of water being “a lot.” The chemical energy of 1kg Of split water is over 4kWh per SINGLE kilogram of water, assuming perfect efficiency. With realistic efficiency, we’re talking more like 7.5kWh per SINGLE kilogram. So electrolysis still requires about 30 times more energy than mining and purifying the water.

The energy requirements for mining and purifying the water are basically a rounding error.

I'm not so sure...

This NASA paper has tons of data about ice mining: https://www.nasa.gov/sites/default/files/atoms/files/mars_ice_drilling_assessment_v6_for_public_release.pdf

They quote 10 kW for 100 gal/day (378 liters), or 30-40 kW for 500 gal/day.

One BFR = 240,000 kg of CH4. The Sabatier process is CO2 + 4H2 -> CH4 + 2H2O.

So you'd need at least 480,000 kg of H2O assuming 100% efficiency and feeding all of the produced water back into the process, if I am calculating this correctly.

500 gal/day = 1892 liters/day = 253 days at 40 kW = 242,880 kWh.

Offline Robotbeat

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Re: Power options for a Mars settlement
« Reply #554 on: 04/29/2018 05:58 pm »
Please actually convert to per-kilogram numbers or you’ll just confuse yourself.

Using the figure of 30-40kW for a day equaling 500 gallons, still yields .48kWh/kg, still greater a factor of ten different from electrolysis (~7kWh/kg). Still nearly a rounding error.
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Offline Joseph Peterson

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Re: Power options for a Mars settlement
« Reply #555 on: 04/29/2018 06:35 pm »

SNIP

You get three per synod if you can turn off the methane generation during the night.

SNIP


Electrolysis, not methane generation.  Methane generation can continue as long as there is enough hydrogen left in the buffer.  The hydrogen buffer is there to allow steady state operations, reducing catalyst degradation.

Offline speedevil

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Re: Power options for a Mars settlement
« Reply #556 on: 04/29/2018 07:21 pm »

SNIP

You get three per synod if you can turn off the methane generation during the night.

SNIP


Electrolysis, not methane generation.  Methane generation can continue as long as there is enough hydrogen left in the buffer.  The hydrogen buffer is there to allow steady state operations, reducing catalyst degradation.

The whole process from whatever it takes to gather resources on. If you can modulate down to match insolation, without peak/averages costing you more than 1/3 in terms of mass, means you can mostly skip batteries.

I was being less careful in my wording as I was correcting a three orders of magnitude implication (500MW vs  around 500kW) for near-term power use.
« Last Edit: 04/29/2018 08:22 pm by speedevil »

Offline ThereIWas3

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Re: Power options for a Mars settlement
« Reply #557 on: 04/29/2018 08:19 pm »
It may depend on what the ground is like below the surface.  Here in Florida the ground is very sandy, and below that it is limestone.  So the "drilling" rig they use for backyard sprinkling systems (between 30 and 100 feet) basically pumps water down under pressure and sucks it back up again.  There is not a rotating "bit" like they use up in New England that has to bore through granite.
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Offline DistantTemple

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Re: Power options for a Mars settlement
« Reply #558 on: 04/29/2018 08:48 pm »
It may depend on what the ground is like below the surface.  Here in Florida the ground is very sandy, and below that it is limestone.  So the "drilling" rig they use for backyard sprinkling systems (between 30 and 100 feet) basically pumps water down under pressure and sucks it back up again.  There is not a rotating "bit" like they use up in New England that has to bore through granite.
I agree a normal rotating bit may not have much use.
Although a NASA study almost recommends relying on the H2O in Gypsum like rock and regolith etc, as there is not clear evidence of where solid ICE is, and it will be an effort to clear regolith load from above the ice.... I bet EM and SX overcome these issues by more prospecting from orbit, or with an additional lander (which no one has mentioned since Red Dragon was cancelled from 2018). Assumig the SX Mars base 1 has ICE to mine, they can mine it with drilling, heat, or machines. I expect they will use modded versions of "Cat" earth movers, some of which are already available as tele-operated, so adding a little autonomy will not be insurmountable. caterpillar has worked with NASA on off-earth equipment.
Once Kilopower is available, the "waste" heat from the temperature "low point" needed to maintain the heat gradient for the Stirling engines may somehow be directly employed in mining water from ice....
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Offline DistantTemple

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Re: Power options for a Mars settlement
« Reply #559 on: 04/29/2018 08:57 pm »
This may be difficult in terms of agreements with NASA, even on Mars... But a Kilopower without its Stirling engines, or power generation could use extended heat pipes as a direct water mining tool. Maybe the unit will need too much shielding to make it useable, but conversely secondary heat pipes may possibly be made 10's of metres long to provide heat for mining water at a distance from the reactor itself. This is using the power directly without all that electric mumbo-jumbo....
Mirrors could also be set up to heat a cathode using concentrated sunlight, and a high capacity heat pipe used to transfer this heat energy to mine large quantities of water.
Others have suggested habitats in ice caverns so made.
« Last Edit: 04/29/2018 09:00 pm by DistantTemple »
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