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#351 2021-04-11 10:27:59

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Going Solar...the best solution for Mars.

Louis wrote:

With 25% efficiency a figure of 0.5 KwH per sol per sq metre on Mars looks about right.

wattage x eff = energy output

500 w / .25 = 2,000 input
not happening on mars

Kbd512 340.25 Watts of power output is correct and it gets lower the further away from the equator that you go.....

Hours of collection is also not going to be for just 500 w / 340.25 = 1.5 hours of exposure and that sucks or these are laying flat on the ground non tracking covered with dust and dirt

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#352 2021-04-11 10:59:47

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,452

Re: Going Solar...the best solution for Mars.

I second GW's plan in post #350.

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#353 2021-04-11 11:04:56

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,452

Re: Going Solar...the best solution for Mars.

Nuclear is the ONLY solution, with a PV array as a peak load enhancement. I don't wanna go to Mars and look out of the hab, only to see the entire landscape covered with PV panels. A hillside hab as envisioned by Robert makes a lot of sense, because if the site is chosen wisely, PV panels can be incorporated adjacent to it. on the same hillside. PV panels generate DC current, and transmission losses accrue the further they would be located from either the inverter or point of power consumption.

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#354 2021-04-11 11:16:19

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,452

Re: Going Solar...the best solution for Mars.

In Graduate School at the University of Wyoming, I was the teaching assistant for the late Professor Victor Ryan, Professor of Nuclear Chemistry. We had a viable Nuclear Chemistry program at that time because the University had a Thorium-based critical mass reactor on campus, in the Engineering School building. That reactor has been disassembled and disposed of after Professor Ryan passed away, but it was considered to be a very safe and easy to use unit--suitable for STUDENT USE. I had occasion to operate it several time under Professor Ryan's supervision. So--Louis: your fear of all things Nuclear is unreasonable. GET OVER IT!

P.S. This is my POST # 2000 on this forum. I'm very proud to be a member of this distinguished group of Mars enthusiasts and scientific professionals.

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#355 2021-04-11 11:41:42

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

Thorium is not very radioactive as I understand it.

I have few fears of operating nuclear power on Mars (as opposed to Earth) in the sense that a major accident will not affect huge numbers of people or take vast areas of farm land out of operation. So, yes, it is a reasonable option because on Mars if you have a disaster, you can just leave it there and forget about it (presuming not so stupid as to site it next door to or upwind of your main settlement).

However, I am not persuaded it's the best option for Mars.

Establishing a nuclear power station of any size on Mars would be a major undertaking involving huge allocation of resource, and nuclear power stations are also labour intensive - labour on Mars will be something in short supply. There are no "ready to go" nuclear power facilities.

I think it's much better to use PV power. It's very incremental. For the first few years you just bring what you need. It won't take years of planning and implementation .It's very flexible. Moreover it's something that Mars can start producing early on, within 5 years of the first humans setting foot on Mars.

Oldfart1939 wrote:

In Graduate School at the University of Wyoming, I was the teaching assistant for the late Professor Victor Ryan, Professor of Nuclear Chemistry. We had a viable Nuclear Chemistry program at that time because the University had a Thorium-based critical mass reactor on campus, in the Engineering School building. That reactor has been disassembled and disposed of after Professor Ryan passed away, but it was considered to be a very safe and easy to use unit--suitable for STUDENT USE. I had occasion to operate it several time under Professor Ryan's supervision. So--Louis: your fear of all things Nuclear is unreasonable. GET OVER IT!

P.S. This is my POST # 2000 on this forum. I'm very proud to be a member of this distinguished group of Mars enthusiasts and scientific professionals.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#356 2021-04-11 12:38:04

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

You do realise we'll be making methane and oxygen and that they can be used to power methane generators? Chemical batteries are not the only storage option for solar power.

PV panels can, in fact work at night, if you have infrared sensitive undersides but it's really not worth the effort for the amount of power you get.

Talking about dust storm darkness is hysterical nonsense. Power output from PV panels rarely reduces more than 60% for any length of time. The odd occasions when (doctored) photos have been shown of the obscured sun, making it look like a total eclipse, are misleading. Insolation reaching the surface never dips below 20% of normal (don't confuse insolation with obscurity measurements). And the reason small rovers shut down during extreme dust storms is because they need to protect themselves from damage. There is no need for PV panelling on the surface to "shut down" and of course there is no reason for robot cleaners not to keep working through dust storms (which have weak force on Mars), cleaning dust off PV panels.

The worst that will happen is you might have to cut back on methane and oxygen production for a while. That does have to be accounted for in planning for solar power. But if you are going nuclear you have to account for downtime caused by system failure (of the kind that is not going to be a major issue for PV which comes from so many different units). 

There is no nuclear facility designed for Mars, tested and operational within 5 years. If there was it would be the largest radioactive facility ever sent into orbit...and I suspect that might create problems.

I think some people just like the idea of nuclear power and aren't looking at the practicalities.There are health and safety issues. If it fails, that's a major issue.

It's much easier to use the PV power route. Take  a couple of 10Kwe meth-ox electricity generators with you - only weigh about 0.5 ton each) and an emergency supply of methane and oxygen (you'll also have plenty sloshing away in the tanks of the cargo Starships, so that could be used as well). Then if you hit a dust storm on arrival you won't lack for energy.

GW Johnson wrote:

The power requirement for a small base (or a large city) on Mars will be the power demand here on Earth,  just much larger numbers.  Why larger?  Because you must add power for activities beyond just heating,  air conditioning (maybe not so much on Mars),  and lighting.  Power is required to make water,  oxygen,  and food.  Without them you die on Mars.  You die in the cold,  too.

The typical daily power demand variation here on Earth is quite a bit higher during the day when people are doing things,  and quite a bit less at night when they are sleeping.  Solar only works when the sun is brightly shining.  You can use batteries to get through the night,  but they are heavy,  expensive,  and you have to send them there.  It would be totally infeasible to send enough batteries to get through a big dust storm's darkness,  which lasts weeks to many months.

So,  what you do is use nuclear as a base load that gets you through the darkness at night,  plus a few percent more.  Use the solar during the day when the sun shines to make the higher daytime power required.  You can restrict activities during bad dust storms to what the nuke can supply.  Use the batteries in your vehicles.  Then you don't have to ship so many batteries to Mars.

I'm all for doing something that actually makes sense.  Base load nuclear plus daytime solar makes a lot of sense.

GW


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#357 2021-04-11 13:18:55

kbd512
Administrator
Registered: 2015-01-02
Posts: 7,862

Re: Going Solar...the best solution for Mars.

louis wrote:

Thorium is not very radioactive as I understand it.

I have few fears of operating nuclear power on Mars (as opposed to Earth) in the sense that a major accident will not affect huge numbers of people or take vast areas of farm land out of operation. So, yes, it is a reasonable option because on Mars if you have a disaster, you can just leave it there and forget about it (presuming not so stupid as to site it next door to or upwind of your main settlement).

However, I am not persuaded it's the best option for Mars.

Establishing a nuclear power station of any size on Mars would be a major undertaking involving huge allocation of resource, and nuclear power stations are also labour intensive - labour on Mars will be something in short supply. There are no "ready to go" nuclear power facilities.

I think it's much better to use PV power. It's very incremental. For the first few years you just bring what you need. It won't take years of planning and implementation .It's very flexible. Moreover it's something that Mars can start producing early on, within 5 years of the first humans setting foot on Mars.

There won't be any "major accidents" because they're not using water as a coolant.  If there's no water, the reactor is operating at a pressure of 3 atmospheres (the pressurization is induced by the pumping of the fuel salt through the primary loop), as opposed to 170 atmospheres, then you're not demanding extreme performance requirements from your primary loop's pressurization pumps, your cooling system and associated piping, or your reactor vessel.  The reactor requires a Graphite moderator in the reactor tank to continue fissioning.  If the reactor gets too hot (above 750C), then it melts the salt plug under the reactor tank, the fuel salt drains into a series of storage tanks beneath the reactor using gravity, fission stops almost immediately because the moderator is required for fissioning to occur, and thus the heat generation stops almost immediately.  The size and weight of all components is dramatically reduced, as compared to boiling water or pressurized water reactors, therefore cost.  If we use Supercritical CO2 in the secondary loop, then there's no water in the plant, period, thus there can be no Hydrogen or steam based explosions, and then all of the equipment associated with electric generation gets dramatically smaller and lighter.

It won't take years of planning and implementation to construct the largest solar array ever constructed merely to supply air and water to a million people?

Hmm...  Yeah, I'm going to go with a hard "no" on that.  Having to cover dozens of kilometers to erect a solar farm of that size is impractical.  Here on Earth, where time is money and nobody needs any air to breathe while the array is being erected, they don't lay out solar panels in the dirt, nor do they use an army of robots to assemble the panels into an array.  There will be hundreds of power inverters and transformers, tens of thousands of kilometers of wiring, and hundreds of thousands of electrical connections.

Siting the power source "right next door" is how you avoid having to run many kilometers of very heavy high voltage power lines.  If you have ten meters of rock or regolith between you and the reactor, then no matter what happens to the reactor, it won't affect anyone else.

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#358 2021-04-11 16:11:10

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Going Solar...the best solution for Mars.

calliban ran the numbers for lose of energy for running anything off from methane and it was horrible what you start with to what you get later.....

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#359 2021-04-11 16:46:20

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,798

Re: Going Solar...the best solution for Mars.

An excellent analysis of the practicality of utility scale solar power installations on Mars by Kbd512 and useful supporting information provided by Spacenut. Some additional information: Utility scale solar power plants in northern Europe have time averaged power density of ~5W/m2.
https://withouthotair.com/c6/page_41.shtml

Has anyone else noticed that all discussions on the development of long-term settlements on Mars always lead back to the same place: Where is the energy going to come from? What then ensues is a drawn out and heated debate. On the one side, engineers look for the energy source with the most adequate power-mass ratio, system reliability and EROI, and that thought process invariably leads to the same place: the need for a nuclear power source. Idealistic individuals cannot accept that conclusion and instead advocate the use of solar energy, basically because they like the idea of it. What then ensues is a long discussion, in which system power-mass, embodied energy, EROI, etc, are examined and the case for solar power gets shot to pieces. The idealists, dissatisfied with the result, then disappear for a while, before returning and advocating exactly the same pet idea all over again. These people are never interested rational analysis, because their position was never rational to begin with. Renewable energy is valuable to them on an emotional level, and any evidence that suggests that it won't work is ignored due to their inbuilt confirmation bias. I have seen variations on this theme played out over and over again on several different forums, including this one. It's the same process every time and it gets repeated as if last time never happened.

But the fact that energy supply continues cropping up as the key issue in discussions of Mars colonisation is telling and should not be surprising. In colonising Mars, we are attempting to rebuild human civilisation, along with all of the infrastructure and manufacturing capabilities needed to make it work. Effectively, an entirely new economy. That is much more difficult and energy intensive on Mars, because nature isn't giving us anything for free. Air is not something that we can simply take, it needs to be manufactured. The same is true of soil. Water is either frozen as hard as stone or present as liquid in the form of hyper-saturated brine. Either way, fresh water costs about as much energy per tonne as concrete does here on Earth. Every building or habitable volume has to be a pressure vessel of some kind. That includes whatever space we use to grow food. Fuel needed for vehicles and hydrocarbons for polymer production, must be produced in a chemical reactor from CO2 and water. The efficiency is poor, making synthetic fuels far more energy expensive on Mars than fossil hydrocarbons dug out of the ground here on Earth. Taken altogether, it will take a lot more energy on Mars to survive at even a basic level. Energy needs to be cheap and very abundant for any human vision of Mars to be at all possible.

Discussions around building a Martian economy provide a useful reminder of what an economy really is. It is people using their labour, leveraged by artificial energy through the use of tools, to rework matter to produce the manufactured products and services that people need or want. As Kbd512 reminds us, energy is the master resource. Other resources may be substitutable to a limited extent. Human beings exploit concentrated ores as a means of reducing the energy investment needed to manufacture raw materials. Recycling becomes interesting as concentrated ores are depleted and it mitigates the rising energy cost of providing raw materials from depleting ore bodies. But there is no substitute for the thermodynamic work needed to produce goods. Industrial countries have achieved high living standards only through the intense use of energy. If you plot global GDP against global energy consumption, you get a virtually straight line. It takes real energy to produce real goods. The use of fiat currency, the growth of complex financial systems to allocate resources, the use of monetary policy and debt; have given some people the false impression that the economy is a non-material and metaphysical thing, whose growth can be governed entirely by financial policy and effectively decoupled from the rising inputs of energy and materials. This is a delusion that stems from the extreme complexity of the modern economy. People that spend their entire lives managing financial instruments lose sight of the fact that those instruments represent real goods of real value. The economy is people making and selling stuff to each other. Complexity makes it easy to lose sight of that, but it does not in any way change the fact. The economy cannot grow without increasing energy use for the same reason that population cannot grow without increasing production of food.

Whether an economy is on Earth or Mars, it is an energy equation. Whenever we access energy, a proportion of that energy is always consumed in the access process. For oil and gas, this proportion is the energy needed to drill the deposit, pipe or ship the hydrocarbons to a refinery and fractionate it into finished fuels. If we are using it to generate electricity or mechanical engine power, it should properly include distribution and end use infrastructure as well. For nuclear power, it includes mining, conversion, enrichment and fuel fabrication, as well as the energy needed to manufacture and decommission the power plant and bury wastes. For renewable energy, it is the energy needed to manufacture and assemble the powerplant, as well as any infrastructure needed for energy storage and decommission the plant at end of life. The energy left over, after access is paid for, is the surplus energy used to run, maintain and even grow the economy. Energy economists define this access cost as the Energy Cost of Energy (ECoE). The lower the ECoE (and the higher the ERoEI), the better, as more energy remains for other activities. One of those activities is the running and repairing of essential infrastructure, like roads, railways, heavy goods transport, government, law enforcement and the production of food. These are all activities that consume energy and have to keep working at a baseline level to avoid systematic collapse. People require minimal amounts of clothing, food, shelter, simply to survive at the most basic level. For any society, baseline ECoE must be beneath a certain level to provide enough surplus energy to maintain essential infrastructure and meet basic needs. The more surplus energy exists, the wealthier society becomes, as more energy is available to invest in more complex products and luxury items associated with high living standards. It also makes the growth of prosperity possible, as surplus energy is available to invest in entirely new infrastructure and the energy infrastructure needed to power it.

On Earth, we have achieved high living standards for a large fraction of the human population thanks entirely to the high ERoEI and low ECoE afforded by fossil fuels. Prior to the use of the steam engine, wind and water power provided the energy needed to run mills and factories and wind drove much of the world's transportation. But these energy sources were either too limited in their extent (hydro) or too diffuse (wind) to produce the surplus energy needed for mass industrialisation and economic growth. Indeed, economic growth remained close to zero until we began accessing concentrated coal reserves and exploiting them to produce rotary motion in steam engines. The high net energy return of coal compared to wind and biomass, allowed the industrial revolution, dramatic improvements in living standards and increasing population in the West. The really significant improvements in personal living standards and high growth in third world population occurred in the 20th century with the exploitation of oil and natural gas and the internal combustion engines needed to convert this energy into mechanical power and electricity. In the fifty years since US conventional oil production peaked in 1971, a combination of new technology and increasing geographical reach of the oil industry have been used to mitigate the depletion of the extremely high ERoEI conventional oil and gas reserves of the United States. Western economies entered a stage of secular stagnation in the 1980s. This is something that puzzled conventional economists who insist on viewing the economy purely as a financial system. When the energy basis of economic activity is understood, the root cause becomes obvious. The North Sea, Alaska and Gulf of Mexico were all producing substitute oil and gas to bolster declining output from the lower 48. The CAFE standards were established, leading to steady improvements in vehicle fuel economy. But none of these new oil sources or efficiency measures could replace the enormous energy subsidy provided by onshore, conventional oil and gas fields in their heyday. Shallow, easy to drill, self-pressurised and controllable at the turn of a valve; oil in the US between 1900 and 1970, was so cheap that it was almost free. And many estimates put the ERoEI value upward of 100. It is no accident that the American way of life after WW2 became the envy of the world. In terms of surplus wealth, the American Middle class enjoyed living standards that far outstripped their European and Japanese rivals. That golden age of growth allowed much of the technological development that occurred after WW2 as well.

What is the implication for a Martian colony? We are attempting to sustain high rates of population growth, growth in manufacturing capability and infrastructure, on a planet where a lot more energy must be expended to meet basic needs. The mass budget for anything imported from Earth is constrained by high transportation costs. On top of that, solar constant is only about 2/5 that of Earth. The case for industrial scale solar electric power on Mars is hopeless. The link below indicates that it is unlikely to be a sustainable even on Earth.
https://www.energy.gov/quadrennial-tech … eview-2015

On Mars, the need for large quantities of low cost electricity, capable of growing at rates that exceed population growth, makes nuclear power an absolute necessity.


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#360 2021-04-11 18:15:56

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Going Solar...the best solution for Mars.

Turn this on its side and make use of the peak to align with the equator.
cut the center out and close it up at 36'  for both sides and you will see mars solar with distance from the equator.

solar-radiation4_orig.jpg

This is the total energy calculation formula which when mars numbers are substitute get really real
main-qimg-b4bd7cf40e1ef3fa863bc2841115eafc

As you can see the energy level falls off quite quick here on earth above Devon Island
worl-solar-radiation.png

http://ecgllp.com/files/3514/0200/1304/ … iation.pdf

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#361 2021-04-12 04:29:10

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,798

Re: Going Solar...the best solution for Mars.

Probably the easiest first nuclear reactor to build on Mars would be an aqueous homogenous reactor.  This is essentially a tank of water containing dissolved uranium nitrate or sulphate salts.  It is inherently self controlling, as power surges lead to an almost instantaneous formation of steam and gas bubbles, which reduce moderation and reduce the effective fuel density in the core.  There is no danger of the sort of reactivity excursion fault that caused the explosion at Chernobyl.  They tend not to be used on Earth for power generation, because they are limited to low operating temperatures <200°C, which limits efficiency.  On Mars, with an abundance of CO2 as secondary side working fluid and low background temperatures, this may be less of a problem.  Abundant waste heat may be a useful commodity for heating greenhouses.

Using nitrate salts and keeping temperatures relatively low reduces problems with corrosion in stainless steels.  If low enriched uranium is available, then reactor tanks can be very compact and high in power density.  If heavy water is used, then we may attempt to use native Martian natural uranium as fuel.  The core could be surrounded by a reflector zone carrying dissolved thorium salts, which would breed uranium-233 for new start-up cores.  Reprocessing fuel is relatively easy, as both fuel and fission product wastes are already in aqueous solution.

I haven't done the sums yet, but natural uranium nitrate dissolved in ordinary water at high concentrations, may form a critical assembly if pumped through a graphite core matrix.  This may provide the basis for an entirely native reactor plant that can be built quickly and easily with entirely Martian resources.

Last edited by Calliban (2021-04-12 04:35:53)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#362 2021-04-12 05:40:08

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

I stopped reading that nonsense as soon as it stated its calculations were based on 10% efficient solar panels. 10%? What century was that written?

Bog standard panels are 15-20% efficient these days. And clearly, on Mars, cost is of little concern, so Space X are going to go higher. I think 25% is a reasonable working figure, although efficiency, certainly in the early stages, could be as high as 30%.

Another factor to bear in mind is that because of Mars's wobble, the optimal zone for PV production extends up to about 30 degrees north. So don't assume being at that latitude is the same as being at that latitude on Earth.

The rest of your analysis is totally flawed. Living standards across the world have risen hugely since conventional oil production past its peak.  The cost of oil in fact is about the same it was 50 years ago. The societies with the highest green energy production are among the most prosperous on Earth, not the least.

The major flaw in your thinking is the idea that energy surplus is the major constraint on increased production whereas in reality it's the amount of labour power that goes into your energy production that is really the key constraint. If your society has to put huge labour power resources into say mining coal (digging down 10 miles to get it out, shall we say) the whole process becomes untenable. Normally it's the market that tells you what's tenable or not. Deep mined coal became increasingly uneconomic for instance, despite the wonderful energy surplus available from coal.

Looking at Mars, we have many of the resources we need to make PV panels, just lying on the surface e.g. silica. Many PV panel production facilities now are highly automated, so very few people are required to supervise the process. Working out how much labour power would go into building the automated facilities is of course tricky - probably impossible. As I say, the end price normally tells you. On Earth price is now telling us PV power is v cheap - it can dip under 2 cents per KwHe in some locations. Of course, the problem you have on Earth is that we don't have very effective storage systems as yet (in terms of price). On Mars, we will have to build methane and oxygen manufacturing facilities to power returning Starships in any case - so there is your ready made energy storage solution, use methane and oxygen to power electricity generators. Combining that with shorter term chemical battery storage will give you an effective energy solution for Mars.

Given that PV panelling on Mars does not require big steel frame supports or land to be rented, the effective costs are going to be much lower.



Calliban wrote:

An excellent analysis of the practicality of utility scale solar power installations on Mars by Kbd512 and useful supporting information provided by Spacenut. Some additional information: Utility scale solar power plants in northern Europe have time averaged power density of ~5W/m2.
https://withouthotair.com/c6/page_41.shtml

Has anyone else noticed that all discussions on the development of long-term settlements on Mars always lead back to the same place: Where is the energy going to come from? What then ensues is a drawn out and heated debate. On the one side, engineers look for the energy source with the most adequate power-mass ratio, system reliability and EROI, and that thought process invariably leads to the same place: the need for a nuclear power source. Idealistic individuals cannot accept that conclusion and instead advocate the use of solar energy, basically because they like the idea of it. What then ensues is a long discussion, in which system power-mass, embodied energy, EROI, etc, are examined and the case for solar power gets shot to pieces. The idealists, dissatisfied with the result, then disappear for a while, before returning and advocating exactly the same pet idea all over again. These people are never interested rational analysis, because their position was never rational to begin with. Renewable energy is valuable to them on an emotional level, and any evidence that suggests that it won't work is ignored due to their inbuilt confirmation bias. I have seen variations on this theme played out over and over again on several different forums, including this one. It's the same process every time and it gets repeated as if last time never happened.

But the fact that energy supply continues cropping up as the key issue in discussions of Mars colonisation is telling and should not be surprising. In colonising Mars, we are attempting to rebuild human civilisation, along with all of the infrastructure and manufacturing capabilities needed to make it work. Effectively, an entirely new economy. That is much more difficult and energy intensive on Mars, because nature isn't giving us anything for free. Air is not something that we can simply take, it needs to be manufactured. The same is true of soil. Water is either frozen as hard as stone or present as liquid in the form of hyper-saturated brine. Either way, fresh water costs about as much energy per tonne as concrete does here on Earth. Every building or habitable volume has to be a pressure vessel of some kind. That includes whatever space we use to grow food. Fuel needed for vehicles and hydrocarbons for polymer production, must be produced in a chemical reactor from CO2 and water. The efficiency is poor, making synthetic fuels far more energy expensive on Mars than fossil hydrocarbons dug out of the ground here on Earth. Taken altogether, it will take a lot more energy on Mars to survive at even a basic level. Energy needs to be cheap and very abundant for any human vision of Mars to be at all possible.

Discussions around building a Martian economy provide a useful reminder of what an economy really is. It is people using their labour, leveraged by artificial energy through the use of tools, to rework matter to produce the manufactured products and services that people need or want. As Kbd512 reminds us, energy is the master resource. Other resources may be substitutable to a limited extent. Human beings exploit concentrated ores as a means of reducing the energy investment needed to manufacture raw materials. Recycling becomes interesting as concentrated ores are depleted and it mitigates the rising energy cost of providing raw materials from depleting ore bodies. But there is no substitute for the thermodynamic work needed to produce goods. Industrial countries have achieved high living standards only through the intense use of energy. If you plot global GDP against global energy consumption, you get a virtually straight line. It takes real energy to produce real goods. The use of fiat currency, the growth of complex financial systems to allocate resources, the use of monetary policy and debt; have given some people the false impression that the economy is a non-material and metaphysical thing, whose growth can be governed entirely by financial policy and effectively decoupled from the rising inputs of energy and materials. This is a delusion that stems from the extreme complexity of the modern economy. People that spend their entire lives managing financial instruments lose sight of the fact that those instruments represent real goods of real value. The economy is people making and selling stuff to each other. Complexity makes it easy to lose sight of that, but it does not in any way change the fact. The economy cannot grow without increasing energy use for the same reason that population cannot grow without increasing production of food.

Whether an economy is on Earth or Mars, it is an energy equation. Whenever we access energy, a proportion of that energy is always consumed in the access process. For oil and gas, this proportion is the energy needed to drill the deposit, pipe or ship the hydrocarbons to a refinery and fractionate it into finished fuels. If we are using it to generate electricity or mechanical engine power, it should properly include distribution and end use infrastructure as well. For nuclear power, it includes mining, conversion, enrichment and fuel fabrication, as well as the energy needed to manufacture and decommission the power plant and bury wastes. For renewable energy, it is the energy needed to manufacture and assemble the powerplant, as well as any infrastructure needed for energy storage and decommission the plant at end of life. The energy left over, after access is paid for, is the surplus energy used to run, maintain and even grow the economy. Energy economists define this access cost as the Energy Cost of Energy (ECoE). The lower the ECoE (and the higher the ERoEI), the better, as more energy remains for other activities. One of those activities is the running and repairing of essential infrastructure, like roads, railways, heavy goods transport, government, law enforcement and the production of food. These are all activities that consume energy and have to keep working at a baseline level to avoid systematic collapse. People require minimal amounts of clothing, food, shelter, simply to survive at the most basic level. For any society, baseline ECoE must be beneath a certain level to provide enough surplus energy to maintain essential infrastructure and meet basic needs. The more surplus energy exists, the wealthier society becomes, as more energy is available to invest in more complex products and luxury items associated with high living standards. It also makes the growth of prosperity possible, as surplus energy is available to invest in entirely new infrastructure and the energy infrastructure needed to power it.

On Earth, we have achieved high living standards for a large fraction of the human population thanks entirely to the high ERoEI and low ECoE afforded by fossil fuels. Prior to the use of the steam engine, wind and water power provided the energy needed to run mills and factories and wind drove much of the world's transportation. But these energy sources were either too limited in their extent (hydro) or too diffuse (wind) to produce the surplus energy needed for mass industrialisation and economic growth. Indeed, economic growth remained close to zero until we began accessing concentrated coal reserves and exploiting them to produce rotary motion in steam engines. The high net energy return of coal compared to wind and biomass, allowed the industrial revolution, dramatic improvements in living standards and increasing population in the West. The really significant improvements in personal living standards and high growth in third world population occurred in the 20th century with the exploitation of oil and natural gas and the internal combustion engines needed to convert this energy into mechanical power and electricity. In the fifty years since US conventional oil production peaked in 1971, a combination of new technology and increasing geographical reach of the oil industry have been used to mitigate the depletion of the extremely high ERoEI conventional oil and gas reserves of the United States. Western economies entered a stage of secular stagnation in the 1980s. This is something that puzzled conventional economists who insist on viewing the economy purely as a financial system. When the energy basis of economic activity is understood, the root cause becomes obvious. The North Sea, Alaska and Gulf of Mexico were all producing substitute oil and gas to bolster declining output from the lower 48. The CAFE standards were established, leading to steady improvements in vehicle fuel economy. But none of these new oil sources or efficiency measures could replace the enormous energy subsidy provided by onshore, conventional oil and gas fields in their heyday. Shallow, easy to drill, self-pressurised and controllable at the turn of a valve; oil in the US between 1900 and 1970, was so cheap that it was almost free. And many estimates put the ERoEI value upward of 100. It is no accident that the American way of life after WW2 became the envy of the world. In terms of surplus wealth, the American Middle class enjoyed living standards that far outstripped their European and Japanese rivals. That golden age of growth allowed much of the technological development that occurred after WW2 as well.

What is the implication for a Martian colony? We are attempting to sustain high rates of population growth, growth in manufacturing capability and infrastructure, on a planet where a lot more energy must be expended to meet basic needs. The mass budget for anything imported from Earth is constrained by high transportation costs. On top of that, solar constant is only about 2/5 that of Earth. The case for industrial scale solar electric power on Mars is hopeless. The link below indicates that it is unlikely to be a sustainable even on Earth.
https://www.energy.gov/quadrennial-tech … eview-2015

On Mars, the need for large quantities of low cost electricity, capable of growing at rates that exceed population growth, makes nuclear power an absolute necessity.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#363 2021-04-12 06:45:25

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,798

Re: Going Solar...the best solution for Mars.

louis wrote:

The rest of your analysis is totally flawed. Living standards across the world have risen hugely since conventional oil production past its peak.  The cost of oil in fact is about the same it was 50 years ago. The societies with the highest green energy production are among the most prosperous on Earth, not the least.

The major flaw in your thinking is the idea that energy surplus is the major constraint on increased production whereas in reality it's the amount of labour power that goes into your energy production that is really the key constraint. If your society has to put huge labour power resources into say mining coal (digging down 10 miles to get it out, shall we say) the whole process becomes untenable. Normally it's the market that tells you what's tenable or not. Deep mined coal became increasingly uneconomic for instance, despite the wonderful energy surplus available from coal.

The flaw is all yours Louis :-)  The surplus energy available from an energy source is inversely proportional to the amount of capital equipment that must be installed to access that surplus.  That capital equipment always has energy and labour costs associated with it.  Making it, installing it, repairing it and disposing of it.  The more equipment needed, the higher those costs will be.  If ECoE is ten times higher, then you need ten times more invested energy (and equipment) and labour to get at each kWh of surplus energy.  This is why shale oil required such huge rates of drilling and failed to be profitable even when oil prices were $100/barrel and interest rates were effectively zero.  There is no escape from the costs imposed by low ERoEI and high ECoE.

Buying a million tonnes of equipment and shipping it to Mars will be a much bigger capital investment, requiring a lot more man hours and invested energy, than a few tens of thousands of tonnes will.  The more capital equipment you need, the larger the amount of invested labour and energy that goes into producing it.  You seem very confident that SpaceX will have the resources to do this.  Exactly how far are those resources going to stretch?  Are they really going to be able to ship a solar farm weighing over a million tonnes and covering several hundred square km to Mars, to power their postulated 1million person colony?  You really think that is going to be cheaper than building a compact nuclear reactor on Mars?

Back to you original point.  Even if your entire society is run by robots and humans are free to spend their lives living in the matrix, EROI still matters.  Even then, surplus energy needs to be above a certain level for your robots to have sufficient excess to maintain and replace infrastructure.  If you want to expand energy supply, ERoEI needs to be above that minimum level.  So ECoE and EROI would still matter even if all production everywhere were completely automated.

As for renewable energy dominant countries being the wealthiest, this is sophistry.  It is true for Norway for example, because of the abundance of hydropower.  Not wind or solar power.  Germany and Denmark have some of the highest electricity rates in the world.  Germany achieved its status as the manufacturing hub of Europe long before it's Energiewende started, during which time they built up the second largest nuclear and largest coal generating base in Europe.  Their position is now protected by sunk investments in capital equipment, patents and manufacturing knowhow.  It is an advantage strong enough to so far survive even the greatest of policy errors by German politicians.  It is telling that German coal consumption remains high even after 20 years of Energiewende.  The only thing that wind and solar power have achieved in Germany is to marginally reduce the coal consumption of its baseboard power plants.  Woo hoo. 

Denmark like Germany, has a large manufacturing base relative to its population.  It therefore has a good balance of trade and it's sunk capital investments provide a certain amount of protection against competition.  Let us hope for their sake it continues to hold out.  Both of these countries continue to consume large amounts of oil and natural gas for space heating, backup power plants, industrial process heat and transportation.  So far, the actual share of renewable energy in Germany's total energy budget has barely broken into double figures.

I find it astounding the lengths you seem to be prepared to go to in order to argue that 2 + 2 doesn't equal 4.  Living standards in the developed world have shrunk significantly since 2000.  Debt-GDP ratio has risen just about everywhere, even if you accept GDP as a reliable estimator of wealth.  Disposible income has gone down in every single major western economy.  Wealth inequality is at it's highest level since the 1930s.  Interest rates have been close to zero and far beneath inflation for the past 12 years.  This would have been unthinkable at the turn of the century.  The US government now funds half of its budget by inflating the national money supply.  If this is a healthy economy, I dread to think what an unhealthy economy would look like.  I wonder how much longer this sort of thing can continue.

Last edited by Calliban (2021-04-12 07:30:45)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#364 2021-04-12 07:35:39

Quaoar
Member
Registered: 2013-12-13
Posts: 665

Re: Going Solar...the best solution for Mars.

louis wrote:

I stopped reading that nonsense as soon as it stated its calculations were based on 10% efficient solar panels. 10%? What century was that written?

Bog standard panels are 15-20% efficient these days. And clearly, on Mars, cost is of little concern, so Space X are going to go higher. I think 25% is a reasonable working figure, although efficiency, certainly in the early stages, could be as high as 30%.

Another factor to bear in mind is that because of Mars's wobble, the optimal zone for PV production extends up to about 30 degrees north. So don't assume being at that latitude is the same as being at that latitude on Earth.

The rest of your analysis is totally flawed. Living standards across the world have risen hugely since conventional oil production past its peak.  The cost of oil in fact is about the same it was 50 years ago. The societies with the highest green energy production are among the most prosperous on Earth, not the least.

With multi-junction technology solar panel can even reach 45% of efficiency, but what happens if a sandstorm darken the sun two months?
You need a backup nuclear reactor anyway.

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#365 2021-04-12 08:24:31

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 3,798

Re: Going Solar...the best solution for Mars.

In answer to Louis's often repeated point that oil prices haven't changed much since 50 years ago.  This is the best graph of historical oil prices I can find.  It goes back to the 1940s and is adjusted for inflation.
https://www.macrotrends.net/1369/crude-oil-price-history-chart'%3ECrude

There is a lot to consider in interpreting oil prices as an indication of the abundance of oil as an energy resource.  But clearly the idea that prices have not risen in 50 years is total BS.  Looking at this graph alone, I think anyone would struggle to find reassurance that shortage wasn't an issue.

The first oil crisis hit in 1973.  Really, we have been locked in a struggle since then to stay ahead of depletion, developing offshore oil, Alaskan oil, polar oil and lately tight oil in a desperate attempt to maintain the resource base.  But the amount of infrastructure and energy invested to maintain production has steadily increased.  It is this, not absolute shortage, that is strangling the life out of Industrial economies.  In recent years, it has become impossible to find a price that will be affordable to consumers and profitable to producers.

Of course, in the simple worldview of a classical economist, shortage never will be an issue, because high prices will always stimulate the search for substitute resources.  That logic breaks down in the case for oil, because it is the dominant energy source for the world's transportation networks and its properties are not easily substitutable.  There are also limits to how much one can afford to pay for an energy source, given the inherent energy requirements of transporting real goods and in more noddy economic terms, the energy intensity of GDP.  So prices cannot rise very high, for very long, before they trigger economic contraction.  So the question becomes - is there an alternative energy source with appropriate properties within an affordable price range?  For oil, so far the answer has been no.

Some oil majors have even publicly admitted that oil production has reached its limits.
https://www.forbes.com/sites/feliciajac … y-for-oil/

Of course, they try to spin it as 'peak oil demand'.  This makes it sound as if less oil is going to be produced because people don't need it.  If container ships, aeroplanes, cars, HGVs and trains, were rapidly transitioning to non-oil based propulsion, that would be true.  But nothing of the sort is happening.  Electric cars remain too expensive for the average person.  Electric aeroplanes are an impractical curiosity.  Electric batteries cannot easily be used to power trucks or ships.  In both cases, range scales in direct proportion with the energy density of the propulsive energy store.  Trains have been partially electrified and in principle, this could continue.  But electrification has if anything been scaled back since 2008.  So there would appear to be scant reasons for feeling warm and fuzzy about the peaking of global oil production.

Last edited by Calliban (2021-04-12 09:17:51)


"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."

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#366 2021-04-12 14:34:15

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,806
Website

Re: Going Solar...the best solution for Mars.

Calliban's inflation-adjusted oil price chart is very informative.  The only reason for the drop to a lower price level about 2015 is the widespread use of fracking technology.  "Peak oil" has been staved off by the advent of the new fracking technology,  which makes recovery from previously-considered depleted fields feasible at these prices.  Where there is oil,  there is usually natural gas,  but there can be gas without oil.  Gas and low-viscosity crude both respond well to the modern fracking.  "Peak coal" is pretty much just about here,  as evidenced by the preponderance of giant mountaintop-removal mines,  which means the switchover from coal to natural gas is quite timely.   

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#367 2021-04-12 15:13:24

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

Dust storms on Mars are self-limiting - if they obscure the Sun to a large degree, then it gets cold and the storm subsides. Research them. You'll find the insolation does not decline for 95% for two months as the anti-solar fanatics would like you to believe. With the worst case scenarios you might see production reduced to 40% of  normal over a couple of months.

As I have explained many times you don't need a back-up nuclear reactor (not that one designed for Mars exists by the way). We will be manufacturing methane and oxygen on Mars. You take a small fraction of that for your emergency back up (to be used in a couple of 10Kw electricity generators).

In the event that you are unlucky arrive in the middle of a dust storm, you take with you a few tons of methane and oxygen to burn it. Remember, the dust storm does NOT prevent you from generating electricity from solar panels. The Starships will have large solar panels and will be able to generate power from those, even before you lay out your PV panelling.

This is a much simpler solution than building a Mars-friendly nuclear reactor, hauling it all the way to Mars, deploying it, and then monitoring/maintaining it.

Quaoar wrote:
louis wrote:

I stopped reading that nonsense as soon as it stated its calculations were based on 10% efficient solar panels. 10%? What century was that written?

Bog standard panels are 15-20% efficient these days. And clearly, on Mars, cost is of little concern, so Space X are going to go higher. I think 25% is a reasonable working figure, although efficiency, certainly in the early stages, could be as high as 30%.

Another factor to bear in mind is that because of Mars's wobble, the optimal zone for PV production extends up to about 30 degrees north. So don't assume being at that latitude is the same as being at that latitude on Earth.

The rest of your analysis is totally flawed. Living standards across the world have risen hugely since conventional oil production past its peak.  The cost of oil in fact is about the same it was 50 years ago. The societies with the highest green energy production are among the most prosperous on Earth, not the least.

With multi-junction technology solar panel can even reach 45% of efficiency, but what happens if a sandstorm darken the sun two months?
You need a backup nuclear reactor anyway.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#368 2021-04-12 15:23:26

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

It's informative but not in the way he would like. Essentially the real price is pretty much where it was 50 years ago.

Yes, oil was very cheap in the 50s and that probably helped with productivity and wealth but I remember reading an article from the beginning of the 70s saying how most people's living standards in the 60s had pretty much flatlined - that was despite cheap oil. That had a lot to do with military expenditure, the creation of a basic welfare state and related tax hikes.

I wouldn't want to be in the fracking business! You're totally at the mercy of events. If the real price of oil rises again we will see more and more fracking, assuming politicians allow that.

Essentially now fossil fuels are more expensive than solar power in large parts of the world.  The only issue is energy storage. I am an optimist that this problem will be resolved within a decade or two. The problem is, whatever the solution, it will require a lot of upfront investment. There isn't much incentive for solar power producers to put in that investment to make solar baseload when they can make a lot of money from less risky propositions. However, eventually it will probably be pressure from the grid owners and operators that will push for solar energy storage.

GW Johnson wrote:

Calliban's inflation-adjusted oil price chart is very informative.  The only reason for the drop to a lower price level about 2015 is the widespread use of fracking technology.  "Peak oil" has been staved off by the advent of the new fracking technology,  which makes recovery from previously-considered depleted fields feasible at these prices.  Where there is oil,  there is usually natural gas,  but there can be gas without oil.  Gas and low-viscosity crude both respond well to the modern fracking.  "Peak coal" is pretty much just about here,  as evidenced by the preponderance of giant mountaintop-removal mines,  which means the switchover from coal to natural gas is quite timely.   

GW


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#369 2021-04-12 15:48:00

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

Horrible! lol  You mean like half of half maybe - 20-25% of initial power. Doesn't matter for the following reasons:

1. Dust storms do NOT prevent you generating PV electricity. They simply diminish the amount of power.

2. Because of 1, the likelihood of you actually needing to produce methane or oxygen to generate electric power is vanishingly small. I am struggling to think of a scenario where this might be required but I can't.

You have to remember that the solar solution is really three way: 

A. PV Panelling (not just for surface deployment but also on your Starships available for use after landing)

B. Chemical batteries (including operational ones on your Starships, available for use after landing).

C. Methox electricity generation from methane and oxygen supplies.

In a very extreme dust storm, you might need to deploy your chemical batteries to help out.


Musk has been tweeting about Tesla having a 400KwH battery available within 3-4 years. But even assuming the current top standard of 250 Watt Hes per kg, 60 tons of batteries across six Starships, say, could deliver 15 MwHs. At 150 KwHes per sol, that would supply with you power for 100 sols.  That's just from the batteries alone. That would cover your essential functions.

The emergency methane-oxygen supply would only be relevant in the most extreme circumstances, probably not yet encountered on Mars. It's a failsafe. If you lose 75% or even 90% of your PV power in converting that to methane and oxygen, it's really not an issue. That would assume in any case you had lost the 30 tons of methox you bring with you. These are extreme scenarios very unlikely to happen - almost impossible to happen but you plan for extreme scenarios when going somewhere like Mars for the first time.

What would happen in dust storm is that you would scale back on (not cease) production of propellant because that is the monster eating up your energy production.

For the solar solution this implies your plant is a little larger than would otherwise be the case perhaps (although I am not sure the nuclear option can assume no downtime ever either, so maybe nukists need to plan for periods of increased production as well). In previous discussions I've factored in those increased requirements and the mass requirements for PV and nuclear are very evenly matched (remember - the nuclear option also needs PV and batteries).






SpaceNut wrote:

calliban ran the numbers for lose of energy for running anything off from methane and it was horrible what you start with to what you get later.....


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#370 2021-04-12 16:01:15

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,806
Website

Re: Going Solar...the best solution for Mars.

Louis:

In the US,  the fracking business pretty much is the entire oil-and-gas business. 

As for inflation-corrected prices,  the reason for the higher price jump 50 years ago was the formation of the OPEC cartel.  If it wasn't for them,  the inflation-adjusted price for oil would be nearer what it was 60-70 years ago.  Which is far lower.

Oil prices respond far more to collusive manipulation than they do actual supply-and-demand.  The reason dwindling reserves did not force them higher yet is that the recent advent of fracking made far more reserves reachable and recoverable. 

The only downside to fracking is geology-related.  If you free gas from the rock pores (which is what fracking does),  it WILL find a way to surface.  In relatively unfractured sedimentary geology,  the easy path to the surface IS the well.  In the heavily-fractured,  contorted geology around mountain belts,  the easiest path to the surface may be the fractured rock instead of the well. 

Gas that follows fractures and comes up away from the well often dissolves into groundwater very much like carbonation.  Which causes sink faucets to burst into flame, or even explode. 

A lot of the known gas reserves are in such fractured geology,  in the Appalachian or Rocky Mountains.  The vast sums of money involved make producers very resistant to the notion that there could be problems associated with their extraction efforts.  But there really are problems,  in that type of geology. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#371 2021-04-12 16:36:27

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,452

Re: Going Solar...the best solution for Mars.

Louis--

" A few tons of methane and oxygen" will NOT suffice. We're talking about success or failure, not a fanciful dream of a society based on Mars without adequate backup. The energy consumption for even a small frontier style outpost is huge. It's beyond chemical storage to meet the needs. We need to keep people warm, generate electricity for Oxygen production and Methane synthesis, grow crops, do useful WORK. Explore.

Let's use metric tonnes: 1000 kg per metric tonne. Methane has a molecular weight of 16, and Oxygen a diatomic molecule is 32.

Two tonnes of Methane is 125,000 moles.

Reaction:  CH4  +  2 O2 ----> CO2  + 2 H2O.

This reaction requires 250,000 moles of O2; 32x250,000 = 8 Tonnes of Oxygen, and all  the associated storage to keep it from evaporating.

The heat of combustion is -890.3 k Joules/mole.  The sign is minus because heat is liberated or produced.

125,000 x -890.3 = 111,287,500 k Joules.

A Joule is a small unit of energy and it takes 1060 Joules to equal a BTU, which is what most heating contractors will sell you with the furnace you want to install in your house to heat it. We're talking about 104,988,208 BTUs in that "couple of Tonnes of Methane." Sounds like a lot until you realize how much natural gas is consumed to heat the average home. The average home furnace is a 100,000 BTU unit, and that's require to heat a 1,500 square foot residence in a northern Midwestern climate--not on the surface of Mars where nighttime temperatures are -50 C. This is a natural gas consumption of approximately 24,000 BTU per hour for comfort in that midwestern residence on Earth, so let's simply state that it will take double that amount of natural gas for a Mars Sol. For mere survival and not comfort. Since a Sol is 25 hours, we'll round up to a 50,000 BTU Methane consumption per hour = 1,250,000 BTU per Sol for Habitat alone--no power generation or anything else like melting ice for water.

I calculate that doing nothing, and just staying barely alive, the 2 Tonnes might last 84 days. Probably a lot less because I'm probably grossly underestimating the usage for heating the hab. If CH4 is used to generate electricity and thaw drinking water and make Oxygen by electrolysis--the crew might make it to only 45 days--cursing the dependence on Solar power the entire time before they die.

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#372 2021-04-12 17:06:11

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

You don't seem to have read my post.

I would be recommending taking 30 tons of methox = 6 tons of methane so more like 250 sols of basic survival under your analysis.

But much more important than that - PV panels do NOT stop producing electricity during a dust storm. I'd be interested to see any evidence to contradict that statement. The best you will be able to come up with is a couple of small NASA rovers closing down to protect themselves when their power reduces to a certain minimum level.

You are never going to have a situation where PV power is below 20% of normal  - and it will be only at the very low end for  a very few sols. Even in the worst case dust storms the power production is probably something like 40% of normal.

Given a Mission One programme will be looking to produce something like the equivalent of 1Mw constant average, that would equate to 400 KwHe constant average - a huge amount of power.

No one's going to die - the worst that will happen is propellant production slows down.


Oldfart1939 wrote:

Louis--

" A few tons of methane and oxygen" will NOT suffice. We're talking about success or failure, not a fanciful dream of a society based on Mars without adequate backup. The energy consumption for even a small frontier style outpost is huge. It's beyond chemical storage to meet the needs. We need to keep people warm, generate electricity for Oxygen production and Methane synthesis, grow crops, do useful WORK. Explore.

Let's use metric tonnes: 1000 kg per metric tonne. Methane has a molecular weight of 16, and Oxygen a diatomic molecule is 32.

Two tonnes of Methane is 125,000 moles.

Reaction:  CH4  +  2 O2 ----> CO2  + 2 H2O.

This reaction requires 250,000 moles of O2; 32x250,000 = 8 Tonnes of Oxygen, and all  the associated storage to keep it from evaporating.

The heat of combustion is -890.3 k Joules/mole.  The sign is minus because heat is liberated or produced.

125,000 x -890.3 = 111,287,500 k Joules.

A Joule is a small unit of energy and it takes 1060 Joules to equal a BTU, which is what most heating contractors will sell you with the furnace you want to install in your house to heat it. We're talking about 104,988,208 BTUs in that "couple of Tonnes of Methane." Sounds like a lot until you realize how much natural gas is consumed to heat the average home. The average home furnace is a 100,000 BTU unit, and that's require to heat a 1,500 square foot residence in a northern Midwestern climate--not on the surface of Mars where nighttime temperatures are -50 C. This is a natural gas consumption of approximately 24,000 BTU per hour for comfort in that midwestern residence on Earth, so let's simply state that it will take double that amount of natural gas for a Mars Sol. For mere survival and not comfort. Since a Sol is 25 hours, we'll round up to a 50,000 BTU Methane consumption per hour = 1,250,000 BTU per Sol for Habitat alone--no power generation or anything else like melting ice for water.

I calculate that doing nothing, and just staying barely alive, the 2 Tonnes might last 84 days. Probably a lot less because I'm probably grossly underestimating the usage for heating the hab. If CH4 is used to generate electricity and thaw drinking water and make Oxygen by electrolysis--the crew might make it to only 45 days--cursing the dependence on Solar power the entire time before they die.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#373 2021-04-12 17:19:29

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

GW Johnson wrote:

As for inflation-corrected prices,  the reason for the higher price jump 50 years ago was the formation of the OPEC cartel.  If it wasn't for them,  the inflation-adjusted price for oil would be nearer what it was 60-70 years ago.  Which is far lower.

Well all you are doing there is showing that Calliban's price chart has nothing to do with the intrinsic value of energy.

But what it does show is that the greatest uplift in people's real incomes across the world took place during a period when real oil prices were much higher than in the period of cheap oil. That rubbishes his whole theory that cheap oil = general uplift in wealth.

Of course what happened between the 70s and now was that there was a huge increase in agricultural production, which always allows people to be allocated to other tasks e.g. manufacturing goods and there were huge advances in automative processes in mining and factories, alllowing for huge increases in output per person. There have been lots of other significant technical advances e.g. containerisation of shipping cargoes, introduction of fast motorways (freeways), general road improvements etc which have all tended to reduce the real price of goods and so raise people's incomes.

Oil prices respond far more to collusive manipulation than they do actual supply-and-demand.  The reason dwindling reserves did not force them higher yet is that the recent advent of fracking made far more reserves reachable and recoverable. 

The only downside to fracking is geology-related.  If you free gas from the rock pores (which is what fracking does),  it WILL find a way to surface.  In relatively unfractured sedimentary geology,  the easy path to the surface IS the well.  In the heavily-fractured,  contorted geology around mountain belts,  the easiest path to the surface may be the fractured rock instead of the well. 

Gas that follows fractures and comes up away from the well often dissolves into groundwater very much like carbonation.  Which causes sink faucets to burst into flame, or even explode. 

A lot of the known gas reserves are in such fractured geology,  in the Appalachian or Rocky Mountains.  The vast sums of money involved make producers very resistant to the notion that there could be problems associated with their extraction efforts.  But there really are problems,  in that type of geology. 

GW

Some little (unexpected) earthquakes have slowed down fracking in the UK. Don't think it's really going to happen here. We are a v crowded country. You need big open spaces.

Although OPEC were artificially raising the price of oil, you have to realise there was an upside. The Arabs of the time didn't really have anywhere much to put the money in their own countries (it's different now of course) and so they had to invest the sudden wealth in Western funds. So there was an investment boom that followed the oil price shock and probably paved the way for the 80s economic boom, in conjunction with the harnessing cheap  labour of hundreds of millions of Chinese peasants moving to work in urban centres.


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#374 2021-04-12 17:36:34

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,433

Re: Going Solar...the best solution for Mars.

Louis I bought a cheap solar flower from dollar tree and it works fine outside but the moment you reduce the amount of light such as bring it inside a home within 3 ft of a window that allows light in it no longer works.....so they stop producing the quantity for designed use and you are now dead as that is what a dust storm will do....

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#375 2021-04-12 17:58:17

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Going Solar...the best solution for Mars.

Sorry, SpaceNut, if that's the quality of your argument, there's no point in arguing with me. Take it up with Musk who is already well advanced with his solar-chemical battery-methox mission to Mars.

SpaceNut wrote:

Louis I bought a cheap solar flower from dollar tree and it works fine outside but the moment you reduce the amount of light such as bring it inside a home within 3 ft of a window that allows light in it no longer works.....so they stop producing the quantity for designed use and you are now dead as that is what a dust storm will do....

Last edited by louis (2021-04-12 17:58:39)


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