Author Topic: Power Systems  (Read 24820 times)

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Marco2001

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Re: Power Systems
« Reply #30 on: August 20, 2010, 08:16:15 PM »
MMRTG has one big advantage - it produces electricyty no mater what happens. It has been tested on Pionier 10 & 11....they are still operating ofter 30 years :-)
As little electric power it may seem to give, the mass/energy ratio is higher then in normal power generator. Apollo missions have proven that RTG can be very usefoul.

MMRTG can generate the power at night.  When the base has no power left, emergency red lights starts to glow. Ever wandered from where those red lights had power? :D

Some systems simply cannot stop working even for a brief moment, becouse of the lack of power (eg.--> HUB Computer). The MMRTG ensures that they will have minimum power for operation, even when other equipement doesn't.

There is one more thing we need to consider. MMRTG gives only 110 W....but that's the small one. The bigger version that would be used on Mars, not only would produce more power, but would also converse more heat into power. In the future the technology will improve. On Mars colony the MMRTG has more flexibility - for instance - the excess heat can power another generator.


Poland here. My time: GMT + 1h
Writing a book about Mars. Any ideas? Type to me.
I'am an Astrobiology/Biology student.

profit004

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Re: Power Systems
« Reply #31 on: August 20, 2010, 11:17:54 PM »
Hey Marco... I am well aware of those advantages and I think they will be used in real mars missions..  I did mention a kinda important thing a few messages ago which is they  are not able to be shut down.

I would like to point out a major downside of an RTG compared to a reactor.. Not saying they will not be used and actually I am certain they will be for everything from heating and emergency power in a hab to running communications and the like... however.. they are always on. Producing heat.

The heat might not seem like a big deal on a planet, but during launch when everything goes up in a nose cone of a rocket, the RTG has to be cooled.  This is not a problem for a small one like less than 100 watts, but when you get to a colony sized 5KW RTG, the heat because it is only 8% efficient is over 50KW's of thermal waste.  ALWAYS ON with no way of turning it off.

Maybe they could launch them inside the fuel tanks somehow with liquid hydrogen to keep it cool...  but it will be a pain to deal with no matter what.

Your reasons for them are valid, your uses are as well, and I do not disagree with them..  Just they cant be much bigger without causing real trouble for launches.

You will note I mentioned in another post this "waste" heat could be put to good use and be far more useful in some respects than the energy produced.

However because reactors can be launched "cool" I think they will probably win out for martian main power generation.
« Last Edit: August 20, 2010, 11:23:52 PM by profit004 »

thedubman

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Re: Power Systems
« Reply #32 on: August 21, 2010, 08:36:36 AM »
All very true, for a real mission- but keep in mind the sim needs not to have to worry about too much of the fine detail, becouse its a sim :) and also the sim is based on an undisclosed future.. which raises the question- what date is the sim based on? 25yrs 50 -100yrs in the future,.. I bet in a hundred years time our time will be like the victorian times to us...

MARS COLONY SIMULATOR 2075 :)

profit004

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Re: Power Systems
« Reply #33 on: August 22, 2010, 03:13:36 PM »
Or like the people in the dark ages looking back on the roman times...

Depending on which way the world swings.

thedubman

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Re: Power Systems
« Reply #34 on: August 22, 2010, 03:30:05 PM »
Agree yes, but the human race (OK there is the advanced civilization that allready existed and have destroyed themselves or flew off to settle on Mars (!) etc theory.. Chariots of the gods stuff etc)...

But in reality the last 50 years the human race has advanced faster than any other time period (talking technology) if human race continues at this rate (and dont do anything stupid) I can see Mars being well visited and at a stage simular to the sim in 50 years.

There are some most exellent ideas being thrown around, and I love how the feasabilty of the ideas are disccused/re-worked/resovled etc by the fourum members...  I wonder what NASA would think..


profit004

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Re: Power Systems
« Reply #36 on: October 10, 2010, 11:05:06 PM »
Regenerative Fuel cells are a storage technology.   Nothing wrong with them but they are a battery, a super-inefficient battery and can be considered identical to a inefficient battery in most cases unless you want to store massive amounts of power and release it very slowly.

That said the ability to store massive amounts of power even with the atrocious inefficiencies makes them attractive...   Just make sure you have a semi-sized group of hydrogen, oxygen and water tanks to store the fuel for them and they could power a laptop for a year. 
« Last Edit: October 10, 2010, 11:08:50 PM by profit004 »

Marco2001

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Re: Power Systems
« Reply #37 on: October 12, 2010, 03:47:54 PM »
Inefficient? Semi-sized group of tanks? Powering a laptop?  
Your wrong.
This is THE most advanced chemical energy storage methode up-to-date. Cars and entire Planes run on this.
 
Quote
"The system is very similar to a rechargeable battery, but it can store four to six times more energy than a battery of the same weight." - NASA Glenn's David Bents.

Quote
The PEM hydrogen-oxygen regenerative fuel cell system is potentially the highest storage capacity and lowest weight non-nuclear energy storage system for extra-terrestrial applications. A solar array equipped unmanned aerial vehicle (UAV) with a regenerative fuel cell energy storage system, for example, could provide a high altitude platform with theoretically unlimited endurance. This potential led NASA to undertake the practical development of a hydrogen-oxygen regenerative fuel cell, initially as solar energy storage for a high altitude, UAV science platform. At present, the RFC system is programmatically part of the NASA Vehicle Systems Program’s Low Emissions Alternative Power (LEAP) Project to further the development of aerospace regenerative fuel cells for high altitude and space missions.
https://www.fuelcelltoday.com/media/pdf/archive/Article_1011_H2-O2%20PEM%20Reg%20Fuel%20Cell%20Energy%20Storage%20System.pdf

Quote
"What makes our regenerative fuel cell unique is that it's closed loop and completely sealed," Bents said. "Nothing goes in and nothing comes out, other than electrical power and waste heat. The hydrogen, oxygen and product water inside are simply recycled over and over again."
http://www.nasa.gov/exploration/home/lunar_fuel_cell.html

Quote
The RFC system was designed to be a completely closed loop test bed for the cyclic operation of fuel cell systems up to 60 kWh (5 kWe X 12 hr). Closed loop means the system with its electrochemical reactants and products is completely sealed; nothing goes into the system other than electrical power and there are no discharges or emissions from the system other than electrical power and waste heat. The RFC system can accomodate a fuel cell stack up to 5.25 kW (100 A at 52.5 V) capacity. The system has a maximum operating pressure of 400 psig. The electrolyzer operates at the system pressure while the fuel cell reactant feeds are regulated down to 50 psig. A 15 kW (150 A at 100 V) electrolyzer is used to charge the reactant tanks to full pressure while running under a current profile that simulates the output of a solar array during the 12-hr daylight cycle. During the nighttime phase of the solar cycle, the fuel cell runs at constant power for most of the cycle.
- https://www.fuelcelltoday.com/media/pdf/archive/Article_1011_H2-O2%20PEM%20Reg%20Fuel%20Cell%20Energy%20Storage%20System.pdf

Poland here. My time: GMT + 1h
Writing a book about Mars. Any ideas? Type to me.
I'am an Astrobiology/Biology student.

profit004

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Re: Power Systems
« Reply #38 on: October 13, 2010, 07:33:23 PM »
Nothing you have quoted there is false, but you have to understand what I have said is not false either.

They are terribly inefficient power wise with maybe a 30% efficiency tops 10-15% more likely after pumping the gases into tanks.

For an extended run time they require a large fuel tank, about 3x as large as a similar gasoline tank for similar energy.

With O2 tanks they require MUCH more storage capacity in their tanks.

Even the NASA solution is only 60KWH of power, which is only 12 hours of generator run time on fuel here on earth. 

I am not saying they are bad but please re-read what I have written and you will see it is in fact the case, and the good and bad points were listed correctly.   I did not realize they had such a weight savings though so that will be a significant factor... but still I consider them a rechargeable battery that loses 70+% of the power you put into it.


Marco2001

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Re: Power Systems
« Reply #39 on: October 14, 2010, 05:25:44 PM »
Actually they have an efficiency of 34% (in theory) and 33% (in practical). The idea is that RFC stores not only power but converts heat from the water synthesis.
But - Agreed that they are inferior when it comes to efficiency.

Size doesn't matter - it's the mass that counts. You can use for instance folded tanks, that you unfold on Mars. In the term of mass to weight - Regenerative Fuel Cells are superior.
Besides - they aren't that big. On this photo you can see RFC that holds power for 12 h: http://img151.imageshack.us/img151/2865/rfcw.jpg

The way I see it - it's a dilemma:
Use normal Batteries that stores power for 2 h with 80% efficiency or equal-massed Regenerative Fuel Cells that stores power for 12 h but with 33% efficiency.

Which ones better? Hard to say.
In certain situations one is better than the other.
For instance.....we have just started the base and we have no power whatsoever. It's more efficient to use batteries, that will help you live threw the night only becouse they store every bit of it that you produce....but...even when you turn OFF everything and run PG at night, you will always live in fear that you might make a mistake once, and drain all the power out.
On the other hand - if you know that your PV Pannels make lot's of energy, it would be a waste to store all that power in batteries that can only hold it for like 2 hours of full consumption. In that case I would prefer to store the power in RFC. That way I won't have to bother with power on night. But what if a dust-storm comes? PVP won't make enough power at day so that RFC won't charge fully. You would need to use PG to power-up main systems, and using RFC in that moment would be a waste of 77% electric power.

So why not make player (base commander) decide how to store his base power suplies by using the POWER STORAGE CONTROL PANEL?
It's basicly the same as Power distibution panel.

It might look a little bit like this:
http://www.sintef.no/upload/Energiforskning/Energylab/Fig2.gif
http://www.zdomain.com/stuff/sandstorm/SM_Trailer_electrical.png
http://img714.imageshack.us/img714/9402/rfc2.jpg

On this panel player would have:
-BATTERY 1 PACK
-BATTERY 2 PACK
-BATTERY 3 PACK
-Backup power
-RFC 1
-RFC 2
-RFC 3
-SOME OTHER POWER STORGE METHODE

Backup power would obviously be a power-storage source that would hold power for several hours of use in case of an emergencies only.

Player would have the ability not only to determine where to store the incoming power from different sources (from PG, PVP, Reactor, other) but would also have the ability to transfer power from one storage to another. Imagine the possibilities that that would enable!
Personaly as a base commander - I would designate one RFC (for instance RFC 3) to be fully charged and then, disable charging/discharging of it. That way I would have 12 h of power as I need it. I would also select Battery pack 1 to be charged primary before charging RFC 1.

IDEA: On start the base could be equiped only with 1 battery pack, 1 Backup power and 1 RFC.
As the base evolve the base commander would buy additional Battery packs or RFC and when they are delivered by a shoutle to Mars, he would go get them and place them in proper storing spots - just like putting PG on platform.
You could see how it gives the players the ability to expand and enjoy the game in the proces. :)

IDEA 2: ...not only that. I also propose that on the start of the base, there would be no PVP outside. Players would find them on start inside the garage, and use Rovers to deliver them in they'r desired place. ---> http://www.archithings.com/wp-content/uploads/2009/11/Mobile-Solar-Power-System-On-Job-Site-588x470.jpg

IDEA 3: Thorium reactor in order to start/stop working needs 3-5 days for cooling/heating up. On start of the new base, players  would need to start it as soon as possible, and manage somehow to live threw the first 3-5 days without nuclear power. If the reactor would need some sort of maintance - you would need to turn it off and wait for it 3-5 days for it to cool down. That make's you plan more doesn't it? :-)

REAL FACT: Apollo 13 had an explosion becouse they transfered half of the oxygen and hydrogen to other containers. That was infact a proces of redistributing storaged power.
REAL FACT: RFC will be used in the next lunar mission (propably) in 2018.

Poland here. My time: GMT + 1h
Writing a book about Mars. Any ideas? Type to me.
I'am an Astrobiology/Biology student.

profit004

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Re: Power Systems
« Reply #40 on: October 14, 2010, 06:27:04 PM »
I had no idea they reached that high of efficiency. That is actually fairly amazing.

But yeah our current solar panels do produce a lot of energy, actually way more than they should I think, mars does not receive that much sun even though there is no atmosphere.

But yes, I certainly agree our current batteries are quite limited.   Also makes me concerned as the batteries seem to be about 20kw's of usable storage capacity (I wish I could get closer but sadly I just do not have a good way to estimate power density for a lithium ion large cell battery in the game) if they are lithium ion and our solar panels should only produce maybe 200 watts at peak sun.  I have not been able to test in the past few times so I am using version 4's solar panels but still should take over 10 days at 10 hours of sun per day to charge the battery to 100%   So there is a lot of gameyness already built into the power systems.

also do you mean PV not PG?  I know Photovoltaics but not PG.


Marco2001

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Re: Power Systems
« Reply #41 on: October 14, 2010, 06:30:17 PM »
PG = Power Generator.

Poland here. My time: GMT + 1h
Writing a book about Mars. Any ideas? Type to me.
I'am an Astrobiology/Biology student.

thedubman

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Re: Power Systems
« Reply #42 on: October 15, 2010, 04:22:31 PM »
I am allways impressed with the level of research and effort  and the questions and debates 'MCO crews' (testers) put in to help create a better MCO..

I did hear once that a 'levels' type of play was considered ie game difficulty 'easy/medium/hard etc'.

Maybe if the sim was created so the difficulty could be ramped,.. so the complexity of the power systems could be increased or dumbed down... I know easy said than done..

Keep up the great debate guys..

Note: If you google Mars Colony - MCO is in top 2-3 searches! news is growing of the project...
« Last Edit: October 15, 2010, 04:38:43 PM by thedubman »

Utini

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Re: Power Systems
« Reply #43 on: October 15, 2010, 08:05:43 PM »
Li-ion batteries run ~150 - 200 Whrs / kg, theoretical Li-ion nanowire batteries are 4 -5 times as high capacity / kg. And large Li-ion batteries are HEAVY. Not quite as bad as lead-acid, but not light at all. However, these batteries do have the problem of capacitance loss if kept charged without deep discharging them regularly, ~15-20% / year. Also, if the internal charging regulator malfunctions and excess energy is added to them, they tend to react .... violently. And since the Li-ion batteries run ~.5 MJ / kg, there's a LOT of energy to be catastrophically released. Which might be an interesting emergency to run through. Also, just as a note, nuclear reactors can be brought up from cold to base load in 6-8 hrs if there are no delays, and can be scrammed literally in a matter of seconds. The residual heat is usually dissipated through the turbines as under normal load. Granted, the power output does describe interesting power curves.

profit004

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Re: Power Systems
« Reply #44 on: October 16, 2010, 01:21:01 PM »
LOL yeah scramming a reactor usually has some other minor consequences but they do shut down fast.  I always understood it though that in a SCRAM the turbines were automatically disengaged and the steam from the primary loop steam generator system went into a bypass mode, with a lot of the time the ECCS coming online as well and the primary core coolant system automatically going into standby mode.

However depending on the method used for control of the space type reactors I can imagine they may take longer to come up to temperature.  They may be a long way under critical or something.