Going Solar...the best solution for Mars.

Calliban · 2021-05-15 18:11:12

louis wrote:

Even if you were right, it still doesn't mean you are right that solar power cannot support a Mars community. If Mars's economy is large enough to pay for PV panels imported from Earth, it's neither here nor there. It's no different from a Caribbean holiday island that imports all its oil. According to you, everyone on the island should be dead but because they have a strong tourist economy they can pay for the oil even though they have no indigenous energy supply.

It doesn't mean that solar power cannot support a Mars economy. Even if ERoEI were less than one, it would still have some value in powering remote applications, where grid connection was not practical and total energy demand was small. Provided it remained a small proportion of total energy demand and a richer energy source existed that could pay for its embodied energy.

Your second point does hold some truth. But if a colony intends to remain dependent upon Earth for its energy supplies as it grows larger, then it really does need to export something of at least equal value to pay for it. The heavier the import mass burden (and capital cost cannot be ignored either) the more difficult that becomes. And the higher the power requirements are, the more difficult it becomes. There needs to be an honest assessment of how much this is going to weigh and how much it will cost. Don't do just assume that it will work because you want it to. As I explained previously, that is a fool's errand.

louis wrote:

Another factor you are ignoring is that energy has to be seen in terms of the overall demands on human labour time in an economy. On Earth in reality in nearly all countries huge amounts of medicine have to be put into caring for sick people, caring for very elderly and infirm people, providing welfare and pension payments to unproductive members of society, keeping maybe 0.1% of the population in prison, maintaining a large police force and court system, maintaining armed forces that can eat up 5% of your GDP, putting in place very complex environmental protection systems. All told I think this must amount to maybe something like 50% of GDP. When you don't have to deploy all those labour resources they are effectively free to be engaged in energy production.

I don't think you have understood what the limitations in net energy yield practically mean. If you are making new solar panels, that have embodied energy requirements, using the output of an existing solar power station to power the process, then there are physical limits to how many new solar panels you can make each year with the energy input of your solar power system. It doesn't matter what proportion of population are engaged in energy production. It is kind of like having a kettle that boils in a certain amount of time. You cannot make tea any more quickly by assigning more people to do it. You could increase the power input to the kettle. You are then improving productivity by increasing energy supply. Or you could get another kettle, which amounts to the same thing. But labour productivity is a function of energy per capita. That stems directly from the first law of thermodynamics.

On you second point: if a higher proportion of people are directly involved in generating the same quantity of energy, it directly follows that their productivity is poorer. Isn't that the very definition of poor productivity? More people needed to do the same job? A smaller proportion of people must therefore produce everything else that is needed. But as I have explained, it doesn't help provide a solution here anyway.

louis wrote:

There is no doubt energy generation on Mars will require more per capita resources per unit of output but there will be the resources available to make that happen.

The problem is, as we have discussed before, living on Mars requires a lot more energy per capita than living on Earth. It is a tougher environment. If you are saying that in addition to that, each unit of energy is more expensive (that is what more resources means) then we are left with a problem. Either Mars is able to export something so fantastically valuable that we can afford to import energy infrastructure, or Martians will be living in what is bluntly described as 'poverty'. That is what happens when the bare essentials of life end up consuming a lot more of your finite resources. Incidentally, that is what has been happening to a lot of previously middle class people in our country and in the US since the turn of the century.

louis wrote:

On Earth, the levelised cost of solar energy has been in freefall for decades. There are now instances where PV energy can deliver electricity at 2 cents per KwHe or under, unsubsidised and the average price is now comparable with other mainstream energy systems.

The cost of PV modules declined rapidly until 1990. There was then a slower decline until about 2009, whereupon it dropped by 90% very rapidly.
https://www.vox.com/energy-and-environm … arket-tech

Until the 1990s, almost all of the cost reductions can certainly be attributed to learning curves. After that, market distortions like tax credits and subsidies started to skew the situation. And since 2008, the financial system has resorted to the sort of practices that mean that prices no longer reflect real costs in a normal financial environment. What that means is that the present low prices of solar modules will not be sustainable in the future.

louis · 2021-05-15 19:48:10

Have you ever looked at any video from Antarctic bases? The first most obvious thing is they don't care about the energy loss...presumably because they know someone will just build a bigger diesel tank and fly in some more diesel. It's probably way down their list of concerns.

On Mars it will be close to the top of our concerns, even though heat loss for instance is far less in the near vacuum of Mars.

Visual intrusion was raised by Oldfart not me - but I have no problem with him raising it...how people live on Mars is important.

If 100 people can be powered by PV power then 1 million people can. You might not like that but I am afraid it is a simple physical fact. Remember - there are 7,000 million people on Earth and we are only talking about 1 million people on Mars, a planet that has a set of material resources v. similar to those available on Earth.

You are forgetting I am not an advocate of Musk's "Million Person City" within 30 years. That's his vision not mine. I see a less steep growth path, but do agree with him that it will be solar powered. People certainly won't be sitting in "tin cans". Where do you get these ideas!? lol But it will be a challenge to create an environment that humans find satifying - I am thinking of starting up a thread on that.

There's nothing to stop us incinerating wet wipes if we wish.

kbd512 wrote:

Louis,
My "maths" are right in line with the energy usage in Antarctica, where absolutely nothing there was built from scratch and the air doesn't require any energy to make it breathable. You're enamored with your ideas, and that's fine, but it doesn't correlate with engineering reality. I have no clue what "visual intrusion" has to do with anything related to engineering. I'm not focused on the aesthetics of anything. I'm squarely focused on the simple and undeniable fact that this endeavor requires far more energy than you think it does, none of your assertions to the contrary square with the power consumption of known life support equipment, and there's absolutely nothing at all on the surface of Mars to provide any energy. Mars is a blank slate, in the literal sense. A city of a million people on Mars won't be powered by solar panels unless the rockets to take stuff there become an order of magnitude larger and we launch at least an order of magnitude more of them.
There are not a million astronauts in the entire world, and nobody else is going to sell everything they own to jump on a rocket and live on another planet where they can't go outside, can't take a shower, can't eat because there's no food, and can't do anything else because there's no energy to do it. The notion that a million people would go to Mars to sit inside a tin can for the rest of their life, washing themselves with wet wipes, but never go outside, is absurd. Try advertising that to people to see how many takers you get. Then test it out for six months here on Earth to see how many people want to live the rest of their natural lives that way. My guess is that you won't get too far.
Speaking of recycling, there'd better be a wet wipe recycling industry on Mars.
Maybe all that high grade stainless steel could be recycled into solar thermal power plants, but photovoltaics and batteries won't cut it, in much the same way that they don't cut it here on Earth. There will never be enough energy to send all the ships back without nuclear power, so we may as well use them for something productive.

kbd512 · 2021-05-16 15:15:07

Louis,

Preparing for winter is at the top of their "to-do list", because once winter sets in, there's no more flying much of anything down there. Do you think they simply fling the doors open and let the cold air rush in, or do you think they do what the rest of us do and try to keep the heat in?

Yes, convective heat loss is less of an issue, but conductive heat loss remains, and on a summer night at the equator, Mars is every bit as cold as the coldest winter night in Antarctica, and then some.

In order to do science, sometimes you have to go outside and put your hands on the subject of your study, and yes, some thermal energy is inevitably lost during that process. The act of exploring and constructing is inherently energy-intensive. If your energy solution lacks the excess capacity to support such activities, then it's time to consider the capabilities of the energy source. Cities are always incremental construction projects, so excess energy is inevitably expended to build, maintain, and then replace habitable spaces that are ultimately supplanted with better / stronger / bigger structures.

There is no city of a million people on Earth that's powered by photovoltaics and batteries. There are cities that use solar power in conjunction with coal, gas, or nuclear power, but none of them run exclusively on photovoltaics and batteries. Those cities that do use solar power have already been built, we're not supplying Oxygen and Nitrogen to them, and they don't require pressurized spaces and electrical power to grow food or house people. All of that stuff requires a crazy amount of power. If you're so energy poor that you can't afford showers, then recycling wet wipes seems like a better idea than burning them.

"If 100 people can be powered by PV power then 1 million people can." <-That statement doesn't work in engineering. There are scaling laws that apply to every power generating technology, as well as every technology, period. That's why your solar powered airliner idea couldn't work. In the world of power generation, scale matters. Orders of magnitude have meaning, whether you accept that or not.

If a piston engine can provide 100hp to a small plane, then a piston engine can provide 1 million horsepower to a gigantic airliner. Sure, a piston engine can provide 1 million horsepower, but what doesn't change is the power-to-weight ratio for a practical piston engine, so we're not talking about something that will fly very well, and we're no longer talking about a practical airliner. That statement clearly doesn't work for aircraft power plants, which is why there are no piston-engined intercontinental airliners today. The weight of the engines and achievable speeds makes the fuel burn worse than it is for gas turbine engines, so they end up costing more to operate. Jet engines didn't merely provide a speed and reliability advantage, they also decreased fuel consumption for a given speed and payload delivered to a given distance. The combination of increased reliability, reduced operating costs, and increased speed is the engineering reason why all airliners made today use gas turbine engines.

So... No, unfortunately, the fact that 100 people can use solar power and batteries for all of their power needs doesn't mean a similar solution can scale to provide power for every human activity under the Sun. Moreover, those kinds of statements don't work for any other aspect of engineering, either.

louis · 2021-05-16 17:59:59

kbd512 wrote:

Louis,
Preparing for winter is at the top of their "to-do list", because once winter sets in, there's no more flying much of anything down there. Do you think they simply fling the doors open and let the cold air rush in, or do you think they do what the rest of us do and try to keep the heat in?
Yes, convective heat loss is less of an issue, but conductive heat loss remains, and on a summer night at the equator, Mars is every bit as cold as the coldest winter night in Antarctica, and then some.

The video I saw, they have a double set of loose fitting swing doors and that's it. They obviously weren't that concerned about heat loss.

When it comes to energy expenditure the rate of heat loss is extremely important.

In order to do science, sometimes you have to go outside and put your hands on the subject of your study, and yes, some thermal energy is inevitably lost during that process. The act of exploring and constructing is inherently energy-intensive. If your energy solution lacks the excess capacity to support such activities, then it's time to consider the capabilities of the energy source. Cities are always incremental construction projects, so excess energy is inevitably expended to build, maintain, and then replace habitable spaces that are ultimately supplanted with better / stronger / bigger structures.

People are not going to be undertaking an EVA every day like on an Apollo mission.

There is no city of a million people on Earth that's powered by photovoltaics and batteries. There are cities that use solar power in conjunction with coal, gas, or nuclear power, but none of them run exclusively on photovoltaics and batteries. Those cities that do use solar power have already been built, we're not supplying Oxygen and Nitrogen to them, and they don't require pressurized spaces and electrical power to grow food or house people. All of that stuff requires a crazy amount of power. If you're so energy poor that you can't afford showers, then recycling wet wipes seems like a better idea than burning them.
"If 100 people can be powered by PV power then 1 million people can." <-That statement doesn't work in engineering. There are scaling laws that apply to every power generating technology, as well as every technology, period. That's why your solar powered airliner idea couldn't work. In the world of power generation, scale matters. Orders of magnitude have meaning, whether you accept that or not.
If a piston engine can provide 100hp to a small plane, then a piston engine can provide 1 million horsepower to a gigantic airliner. Sure, a piston engine can provide 1 million horsepower, but what doesn't change is the power-to-weight ratio for a practical piston engine, so we're not talking about something that will fly very well, and we're no longer talking about a practical airliner. That statement clearly doesn't work for aircraft power plants, which is why there are no piston-engined intercontinental airliners today. The weight of the engines and achievable speeds makes the fuel burn worse than it is for gas turbine engines, so they end up costing more to operate. Jet engines didn't merely provide a speed and reliability advantage, they also decreased fuel consumption for a given speed and payload delivered to a given distance. The combination of increased reliability, reduced operating costs, and increased speed is the engineering reason why all airliners made today use gas turbine engines.
So... No, unfortunately, the fact that 100 people can use solar power and batteries for all of their power needs doesn't mean a similar solution can scale to provide power for every human activity under the Sun. Moreover, those kinds of statements don't work for any other aspect of engineering, either.

There are certainly plans for 100% solar powered cities. Those plans appear perfectly feasible to me.

You are trying to apply the laws of thermodynamics where they don't apply! If you can have a settlement of 100 powered by PV systems, you could have 10,000 settlements of 100 people, side by side to give you your one million person settlement.

kbd512 · 2021-05-16 18:41:13

Louis,

Show me a city on Earth with a million or a half million or a quarter million people that was built from scratch using photovoltaics and batteries, because no such thing exists (edit: to my knowledge). If you think it's feasible to do that, then show me a single working implementation. I'm not interested in plans. We have plans to colonize planets in other solar systems. Thus far, plans is all that they are.

The laws of thermodynamics are at play all the time, unless you're going to use building materials that require no heat to produce. The mere fact that you think they aren't at play tells me that you're not accepting of objective reality. The real question is "Why?", though. What causes you to become so fixated on something that simply doesn't work?

If people are building a city, then they will absolutely be doing EVAs everyday.

Last edited by kbd512 (2021-05-16 19:46:24)

Calliban · 2021-05-17 11:48:47

Louis, there is no point in arguing. You have nothing to argue with. You are trying to advocate a technological option without knowing enough about it to make the case. And by your own admission you aren't interested in engineering. You aren't interested in listening or learning about it and dislike being lectured. So why try to argue the toss on what is clearly an engineering topic? You say that the laws of thermodynamics don't apply. What the heck!? Do you even know what they are? How can the conservation of energy not be relevant to a discussion on energy systems? Do you know how a solar panel works? Do you know how a nuclear reactor works? How about a battery? You don't appear to understand the role that energy plays in society.

The purpose of this forum is to develop concepts that might one day be useful in the exploration and colonisation of Mars. This topic doesn't appear to be doing that. Advancing this topic requires at least some level of engineering analysis. Which you aren't interested in, by your own admission. So what are you hoping to achieve? You seem to have a sort of quasi-religious obsession with solar power which is beginning to look like a mental health issue. But no amount of religious belief in solar panels is going to develop practical systems that we can use on Mars. It puzzles me why anyone would hold such passion for bland technologies that they don't even understand.

Last edited by Calliban (2021-05-17 12:25:10)

tahanson43206 · 2021-05-17 13:26:35

For Calliban and kbd512 ...

As a reminder, Louis is filling an important role in the forum, by setting up challenging scenarios for more knowledgeable members to explore.

The beneficiaries of your efforts are NOT Louis! They are the readers (members and non-members) who can learn from your work.

Please keep them in mind as you compose your posts.

Louis is here to stimulate creativity ... when you write, please consider tackling the specific errors that Louis makes and then resolutely, clearly and in a step by step manner, refute them.

In addition, I am calling for exploration of the feasibility of some version of Louis' wild-eyed concepts.

There was a brief moment when I thought the knowledgeable members might tackle the specifics of how to set up a solar panel manufacturing facility on Mars. The ideal solution (from my perspective) would be a package with self-contained power source able to fit in a single Starship, and begin making solar panels shortly after landing.

(th)

Calliban · 2021-05-17 14:35:11

Yeah I know. It was small of me.

I have a book on thin-film PV technology. I am no expert on semiconductors, but am interested to learn more. The challenge to making this work on Mars, is to reduce embodied energy. Efficiency is limited by things like impurities, floating bonds and resistance losses resulting from the very low voltage imposed by the low breakdown voltage of the PV layer, which is about 50 microns thick. So the energy yield per unit area is limited by things that we probably won't be able overcome. But embodied energy is something that we do have control over, by selection of appropriate materials.

The actual semiconductor material in thin film PV is a doped layer of silicon, microns thick. So it is not unrealistic to import it from Earth, along with the silver for top contacts and aluminium backplate, which is really just foil. The cover glass needs to be made insitu, as it is relatively heavy. The aluminium backplate can sit on glass or a layer of sintered regolith. On Earth, large amounts of steel and concrete are used to make support frames for the panels. These need to stand up to wind loading and resist oscillations that could damage the panels. And they need to able the panels according to the angle of the sun. On Mars, without rain, ground water and with far less wind, I would suggest making support panels out of rammed soil or Marscrete, both of which have low embodied energy. Cover the surfaces in a thin layer of impermeable polymer material, to eliminate the possibility of frost damage to surfaces.

For conductors from the panels to inverters and transformers and transmission lines, I would recommend using steel rather than aluminium. It has more than double the resistivity of aluminium. But it is much easier and less energy intensive to make. And there will be few if any issues with corrosion on Mars.

Those are my initial thoughts for reducing embodied energy. A lot more work is needed. Whether it will be enough to make the concept viable, I do not know.

Last edited by Calliban (2021-05-17 14:45:14)

SpaceNut · 2021-05-17 16:34:24

Things that I have learned from home grid and standalone have been that the 100% of collected to what is design is not achieved by grid tied as the units typically come in at 70 ish percent year round performance for power collected to used by the customer which is an under designed install of panels with net metering.
The off grid people tend to see that the meters show that what you wanted must be rationed and act accordingly for the solar units that they have installed with the batteries.

So a Mars install not only needs more panels to the same levels of battery storage as it would on earth but you also need the mentality to be willing to ration power to keep reserves as high as possible for the next days collection. This is something that most could and would not tolerate very well. As Mars is an off grid living design from day one if there is no stable nuclear power in the mix.

Mars needs 2.6 times the meters for the same collection and if the solar on earth needs 30% more on top of that value at a minimum not to mention the lessening values of collected that are caused by the dust depositing. That said we are now over 3 times the panel count for the same grid as what we would set up here on earth with no change to the battery size of which I would up it a little but not to much as they would then be under charging and building up cell barriers with in the topology of the batteries designs.

louis · 2021-05-17 18:20:14

The Saudis are starting to build a million person urban settlement powered entirely by renewable energy:

https://www.dezeen.com/2021/01/13/line- … city-neom/

Construction is supposed to start this first quarter 2021.

Sounds like an interesting project.

kbd512 wrote:

Louis,
Show me a city on Earth with a million or a half million or a quarter million people that was built from scratch using photovoltaics and batteries, because no such thing exists (edit: to my knowledge). If you think it's feasible to do that, then show me a single working implementation. I'm not interested in plans. We have plans to colonize planets in other solar systems. Thus far, plans is all that they are.
The laws of thermodynamics are at play all the time, unless you're going to use building materials that require no heat to produce. The mere fact that you think they aren't at play tells me that you're not accepting of objective reality. The real question is "Why?", though. What causes you to become so fixated on something that simply doesn't work?
If people are building a city, then they will absolutely be doing EVAs everyday.

louis · 2021-05-17 18:27:52

I don't see the rush. A vertical set up (ie in a Starship) for a manufacturing facility would not be ideal. It's much more likely the manufacturing facility will be laid out horizontally in appropriate habs. Maybe large semi cylinder sections like "Nissen huts" from WW2 (but obviously pressurised).

There's no mystery about the machinery. It can be brought from Earth as a turnkey facility Some of the large units may have to be disassembled and reassembled on Mars.

As the Mars colony becomes more sophisiticated it can begin to manufacture more and more of the manfacturing units.

There is abundant silica and aluminium on Mars, which makes up the bulk of a PV panel. There may be some raw materals that need to be brought from Earth for some years and source on Mars are identified.

tahanson43206 wrote:

For Calliban and kbd512 ...
As a reminder, Louis is filling an important role in the forum, by setting up challenging scenarios for more knowledgeable members to explore.
The beneficiaries of your efforts are NOT Louis! They are the readers (members and non-members) who can learn from your work.
Please keep them in mind as you compose your posts.
Louis is here to stimulate creativity ... when you write, please consider tackling the specific errors that Louis makes and then resolutely, clearly and in a step by step manner, refute them.
In addition, I am calling for exploration of the feasibility of some version of Louis' wild-eyed concepts.
There was a brief moment when I thought the knowledgeable members might tackle the specifics of how to set up a solar panel manufacturing facility on Mars. The ideal solution (from my perspective) would be a package with self-contained power source able to fit in a single Starship, and begin making solar panels shortly after landing.
(th)

louis · 2021-05-17 18:34:32

I am interested in engineering, I just don't claim to have knowledge of the subject. You may have been confusing a joke with a serious statement on my part. I don't need an engineering degree to see PV roll unloaded from the back of a vehicle or check out performance of various panels, space rated and otherwise. You keep trying to make an economic law of thermodynamics. Of course it's relevant but an energy surplus is an energy surplus.

What I don't understand is why you and others are so confident in dismissing the solar solution even though Musk, a man with a good understanding of engineering issues doesn't and plans to power his Mars colony with PV power. The best you can come up with is something along the lines of "he'll eventually see the error of his ways". Why should he? He knows how PV performs on Mars.

Calliban wrote:

Louis, there is no point in arguing. You have nothing to argue with. You are trying to advocate a technological option without knowing enough about it to make the case. And by your own admission you aren't interested in engineering. You aren't interested in listening or learning about it and dislike being lectured. So why try to argue the toss on what is clearly an engineering topic? You say that the laws of thermodynamics don't apply. What the heck!? Do you even know what they are? How can the conservation of energy not be relevant to a discussion on energy systems? Do you know how a solar panel works? Do you know how a nuclear reactor works? How about a battery? You don't appear to understand the role that energy plays in society.
The purpose of this forum is to develop concepts that might one day be useful in the exploration and colonisation of Mars. This topic doesn't appear to be doing that. Advancing this topic requires at least some level of engineering analysis. Which you aren't interested in, by your own admission. So what are you hoping to achieve? You seem to have a sort of quasi-religious obsession with solar power which is beginning to look like a mental health issue. But no amount of religious belief in solar panels is going to develop practical systems that we can use on Mars. It puzzles me why anyone would hold such passion for bland technologies that they don't even understand.

tahanson43206 · 2021-05-17 18:39:37

For Louis re #461

Thank you for encouraging further discussion (and hopefully development) of your idea to employ solar panels on Mars.

There was a brief moment when I thought the knowledgeable members might tackle the specifics of how to set up a solar panel manufacturing facility on Mars. The ideal solution (from my perspective) would be a package with self-contained power source able to fit in a single Starship, and begin making solar panels shortly after landing.

Reading the text above carefully, I find that the words imply ONLY that the components of the system could be packaged in a single Starship. Your idea that the facility might actually OPERATE inside a landed Starship is fascinating in its breathtaking Majesty!

Bravo!

In a stroke, you have managed to make an already difficult task almost infinitely difficult.

Since my request is directed to those forum members who are knowledgeable, and willing to tackle this problem, I'm going to assume they will discount your magnification of the difficulty.

Since this is your topic, you have the option of closing down this line of inquiry.

(th)

SpaceNut · 2021-05-17 18:51:43

One day one and more there is no surplus solar energy with a poorly supplied system via the starship as its not even able to supply enough energy to make fuel for one returning ship when 5 are required to deliver the system....

I did alot of research back on the red colony forum of the day when Louis and I were both active there and the making of solar is no simple process and requires quite bit of refined minerals and such that are not part of the machines that make them. The minerals that we use dictate the equipment and even the out come of the efficiency.

kbd512 · 2021-05-18 14:27:57

Louis,

This city of a million people will use solar, wind, and Hydrogen for energy storage, not batteries, and it will cover some 10,000 square miles. The high speed train that connects all nodes in the city to achieve the design goal of moving from one end of the city to the other in 20 minutes would have to move at a speed of 512kmh, but no high speed train is currently capable of doing that.

Will this city be built with solar powered electric trucks and excavators, or will the construction equipment use diesel engines?

Are all of the building materials produced using solar power?

Where is their food source coming from, and will that be entirely powered with wind and solar (seed planting to market, without oil and gas)?

Are they using solar power to desalinate sea water?

That's quite literally what we're talking about doing.

If this city is being built using surplus energy provided by oil and gas, then it's not an analog for what you're talking about doing.

What I want to see is a city built using nothing but wind / solar power. The machines need to be battery or corded-electric powered, the materials used should be made using wind / solar power, and the energy storage medium, whatever that is, can't be supplied by oil and gas wells or coal.

At that point, how much tonnage do we need to ship, can that realistically be done using chemical rockets, and do we have a practical operating model going forward?

I can already guarantee that it's more for solar than it is for nuclear, and not by a little bit. The question is whether or not we go far outside the realm of what is practical or reasonable.

For example, if half of every ton of materials we ship is solar panels or batteries, then how practical is that for building out the colony?

It's not that it's utterly impossible, it's that it's so impractical as to beg the question of why we're continually trying to fit a square peg into a round hole.

Solar power is not the solution to all energy problems. Power storage remains humanity's greatest weak point when it comes to energy delivery. We don't have scalable methods for storing energy, except in the form of liquid hydrocarbons that can be burned in an oxidizing atmosphere that Mars clearly lacks. We either come up with vastly more energy dense batteries than what we currently have, or we admit that we've reached the technological limit of batteries and have to consider alternatives, whether fuel and oxidizers or nuclear power. In terms of total tonnages processed in-situ or delivered from Earth, nuclear materials provide orders of magnitude more energy density over fossil fuels and batteries, so more energy can be devoted to growth or less delivered (from Earth) tonnage is required.

I think you're demanding more of technology than it can presently deliver. If energy storage changes drastically over the next ten years, then we can revisit the practicality of using nothing but solar and batteries, but until then, it's not a realistic plan, and that's not being dismissive of SpaceX's plans, it's merely restating what's plainly obvious to engineers who understand the mathematics behind current energy technologies.

louis · 2021-05-18 18:17:40

kbd512 wrote:

Louis,
This city of a million people will use solar, wind, and Hydrogen for energy storage, not batteries, and it will cover some 10,000 square miles. The high speed train that connects all nodes in the city to achieve the design goal of moving from one end of the city to the other in 20 minutes would have to move at a speed of 512kmh, but no high speed train is currently capable of doing that.

China already has a maglev line with a top speed of 430kph and has plans for a 620kph line:

https://edition.cnn.com/travel/article/ … index.html

So 512 kph sounds possible.

Will this city be built with solar powered electric trucks and excavators, or will the construction equipment use diesel engines?
Are all of the building materials produced using solar power?
Where is their food source coming from, and will that be entirely powered with wind and solar (seed planting to market, without oil and gas)?
Are they using solar power to desalinate sea water?
That's quite literally what we're talking about doing.

I can't answer your questions. I imagine a lot of diesel vehicles will be used in the construction. But that's not the same as saying solar power construction would be impossible. I can imagine robot rovers powered by PV panels/batteries gather materials that are turned into Mars concrete, cement and bricks. Concrete and cement can be applied by PV powered robots. I really don't see the issue. That it hasn't been done before is not surprising. It doesn't mean it can't be done.

If this city is being built using surplus energy provided by oil and gas, then it's not an analog for what you're talking about doing.

What I want to see is a city built using nothing but wind / solar power. The machines need to be battery or corded-electric powered, the materials used should be made using wind / solar power, and the energy storage medium, whatever that is, can't be supplied by oil and gas wells or coal.

Well obviously there's nothing like that yet. I would say of course we can store solar power as methane and oxygen. I don't know, but these may be better power sources for some heavy duty machinery.

At that point, how much tonnage do we need to ship, can that realistically be done using chemical rockets, and do we have a practical operating model going forward?
I can already guarantee that it's more for solar than it is for nuclear, and not by a little bit. The question is whether or not we go far outside the realm of what is practical or reasonable.
For example, if half of every ton of materials we ship is solar panels or batteries, then how practical is that for building out the colony?
It's not that it's utterly impossible, it's that it's so impractical as to beg the question of why we're continually trying to fit a square peg into a round hole.

You don't get a free ride on nuclear! You have to show what mass is required for that! Currently the only near example we have are experimental kilopwatt units clocking in at 1.5 tons per 10 Kw power - giving very similar sorts of tonnages to solar (no one is going to bother with your ridiculous idea that we have to use the same heavy frames and structures we do on Earth).

As previously explained we don't need that many additional batteries. There will be batteries in vehicles and in Starships (used for actuating fins).

Batteries (I'd say about 20% of the initial system mass, but falling rapidly as the colony grows, going down to maybe 2-5%) will be used to help smooth generation to meet demand.

But the main form of storage will be manufactured methane and oxygen. That won't need to imported from Earth. Initially the generators (about 0.5 ton per 10 Kwe power) will be required but within 10-20 years we should be able to manufacture those on Mars.

PV panel manufacture could start within a few years, certainly within 10 years, after which Mars will be importing very small amounts of the mass for its energy systems.

Solar power is not the solution to all energy problems. Power storage remains humanity's greatest weak point when it comes to energy delivery. We don't have scalable methods for storing energy, except in the form of liquid hydrocarbons that can be burned in an oxidizing atmosphere that Mars clearly lacks. We either come up with vastly more energy dense batteries than what we currently have, or we admit that we've reached the technological limit of batteries and have to consider alternatives, whether fuel and oxidizers or nuclear power. In terms of total tonnages processed in-situ or delivered from Earth, nuclear materials provide orders of magnitude more energy density over fossil fuels and batteries, so more energy can be devoted to growth or less delivered (from Earth) tonnage is required.
I think you're demanding more of technology than it can presently deliver. If energy storage changes drastically over the next ten years, then we can revisit the practicality of using nothing but solar and batteries, but until then, it's not a realistic plan, and that's not being dismissive of SpaceX's plans, it's merely restating what's plainly obvious to engineers who understand the mathematics behind current energy technologies.

My view is that with PV energy now becoming so cheap (ie uses so few resources, particularly labour time) that even though its EROI is not as great as some other forms of energy it is actually the way forward. Chemical battery storage has its limitations but is very useful for a range of tasks including smooth output of electricity and transportation. But most energy storage will accomplished by the creating of fuels that can work with oxygen to generate electricity as and when needed (ie when direct PV power is not available). It's not clear what form of fuel storage will win out on Earth. At utility level it might be hydrogen. On Mars, because we will have to be producing methane and oxygen to power Starships, using some of that methane and oxygen for energy storage is a fairly obvious option.

Producing methane and oxygen on Mars is not demanding too much of technology - it's just not the sort of thing we do on Earth because of the cost (currently) and the fact we have freely available air.

I don't think Space X have any doubt on this and I don't either, that you can supply a Mars colony's energy needs from PV power plus a smallish element of chemical batteries. Not to say it's "easy" - everything has to be Mars-rated of course - but I think it's doable.

louis · 2021-05-18 18:25:39

You would never switch to reliance on Mars-based PV manufactured supply without having a stockpile of imported PV power systems ready for use if Mars manufacture went wrong. But, really, things have moved on a lot since (the much fun) Red Colony days. PV manufacture is so automated now...this is really doable. Not just that, but with advances in 3D printing, you can begin producing on Mars a lot of the parts of the manufacturing facility, so again reducing mass importation from Earth.

I don't think it's fanciful to envisage that within 15 years the Mars colony could be produing 95% of the energy system itself using Mars ISRU, including the manufacturing facility itself.

SpaceNut wrote:

One day one and more there is no surplus solar energy with a poorly supplied system via the starship as its not even able to supply enough energy to make fuel for one returning ship when 5 are required to deliver the system....
I did alot of research back on the red colony forum of the day when Louis and I were both active there and the making of solar is no simple process and requires quite bit of refined minerals and such that are not part of the machines that make them. The minerals that we use dictate the equipment and even the out come of the efficiency.

kbd512 · 2021-05-18 18:54:09

Louis,

I never said it would be impossible to power electric construction vehicles using solar panels. The question is, if it's such a reasonable and easy thing to do, then why do I always see diesel powered trucks and heavy equipment building everything, rather than electric heavy equipment?

That's a fair question with no real answer from you or anyone else asserting that electric vehicles could replace diesel powered construction equipment. Given that so much construction occurs inside cities and that cities already have plenty of electric power availability, I wonder why we had to wait for solar anything to begin using electric construction equipment. After all, the equipment cost less to operate, there are fewer moving parts, and no shortage of power cables, so why the heck not?

If you use up the batteries in vehicles to supply power at night, then they can't provide power to construct anything during the daytime. After the construction is complete, then vehicle batteries could feasibly be tied to the power grid to supply additional power.

Nuclear power isn't "free anything". I've already told you how much the reactors would weigh and what's required, but you haven't come back with anything but baseless assertions that something's missing or not accounted for. You need to provide a concrete example of what you want to see, and then refute a claim with evidence (numbers based upon real-life examples), if you believe otherwise.

Speaking of ridiculous ideas, you're the one who brought up commercial photovoltaic panels. I provided links to the actual product specification sheets for the thin film photovoltaic panels indicating how much each panel weighed, to show why we're not talking about commercial anything to supply the power. I said we could feasibly get down to around 2kg per square meter, and then you came back with some nonsense about using commercial thin film panels that weigh 12kg per square meter. It wasn't feasible to achieve a power generating and storage solution within an order of magnitude of the weight of an equivalent nuclear power generating system, even using panels that weigh in at 2kg/m^2. Transport to Mars is clearly part of the problem.

Objective reality is that the resource consumption associated with transport, per ton of delivered whatever, is far outside the realm of practicality with chemical rockets for purposes of building a city of a million people, even for the nuclear power generating solution, never mind the solar plus storage power generating solution that weighs at least an order of magnitude more to provide equivalent capability.

louis · 2021-05-19 09:27:08

kbd512 wrote:

Louis,
I never said it would be impossible to power electric construction vehicles using solar panels. The question is, if it's such a reasonable and easy thing to do, then why do I always see diesel powered trucks and heavy equipment building everything, rather than electric heavy equipment?
That's a fair question with no real answer from you or anyone else asserting that electric vehicles could replace diesel powered construction equipment. Given that so much construction occurs inside cities and that cities already have plenty of electric power availability, I wonder why we had to wait for solar anything to begin using electric construction equipment. After all, the equipment cost less to operate, there are fewer moving parts, and no shortage of power cables, so why the heck not?

It's a fair question but it relates to Earth not Mars. On Mars diesel fuel, unless imported, won't be available and you'll need a bespoke oxygen supplyas well to burn it. I think we can rule out diesel from the equation. Methane can be used to operate big vehicles and machinery - that already happens on Earth and we will be producing methane and oxygen on Mars in any case, to power the propellant plant. So if all electric vehicles and machinery are an issue that is probably what we would use.

If you use up the batteries in vehicles to supply power at night, then they can't provide power to construct anything during the daytime. After the construction is complete, then vehicle batteries could feasibly be tied to the power grid to supply additional power.

You're misunderstanding my proposal. Chemical batteries would be used to smooth electricity ouput e.g. to cope with sudden demand surges. They would also be used for emergency power if there was some catastrophic collapse in the energy system e.g. a serious meteorite strike perhaps. But generally I think methane and oxygen would be used to store energy and run the overnight services. A 10Kwe methox generator weighs in at under 500 kgs. So for Mission One, at least two of those would be required. The number in service would of course grow over time and larger generators would be imported or constructed on Mars. Processes like clothes washing, heating up water and charging up batteries, would take place during the day.

Nuclear power isn't "free anything". I've already told you how much the reactors would weigh and what's required, but you haven't come back with anything but baseless assertions that something's missing or not accounted for. You need to provide a concrete example of what you want to see, and then refute a claim with evidence (numbers based upon real-life examples), if you believe otherwise.

I want to see examples of commercially available reactors, how much they mass and how they would be deployed on Mars (in habs? outside habs? with radiation protection or not?) and how they would be maintained.

Speaking of ridiculous ideas, you're the one who brought up commercial photovoltaic panels. I provided links to the actual product specification sheets for the thin film photovoltaic panels indicating how much each panel weighed, to show why we're not talking about commercial anything to supply the power. I said we could feasibly get down to around 2kg per square meter, and then you came back with some nonsense about using commercial thin film panels that weigh 12kg per square meter. It wasn't feasible to achieve a power generating and storage solution within an order of magnitude of the weight of an equivalent nuclear power generating system, even using panels that weigh in at 2kg/m^2. Transport to Mars is clearly part of the problem.
Objective reality is that the resource consumption associated with transport, per ton of delivered whatever, is far outside the realm of practicality with chemical rockets for purposes of building a city of a million people, even for the nuclear power generating solution, never mind the solar plus storage power generating solution that weighs at least an order of magnitude more to provide equivalent capability.

Will respond later re mass of PV panels.

kbd512 · 2021-05-19 11:59:53

Louis,

If we had rockets that were 10 times more efficient than current chemical rockets, then solar and energy storage starts to become feasible. If the rockets are 100 times more efficient, then as you've stated, nuclear probably isn't worth the hassle. That's why I stated that neither option is truly practical for building a city, if we're stuck with chemical rockets. More than 90% of everything we ship must be propellant using chemical rockets. Even freight shipped via airliners is vastly more practical than using chemical rockets, yet those are so costly to operate that typically small / light, high-value items are shipped by air, such as consumer electronics.

The correct propellant mass figure for delivering people and cargo to the surface of Mars is zero. We absolutely need a space elevator at Mars, which is feasible using existing Aramid fibers, not CNT or BNNT or anything so exotic. Going to and from Mars pretty much requires propellant expenditure, but the propulsion system needs to be a high-efficiency electric system of some kind, with a 2000s+ Isp, and 5,000s or more being highly desirable for practical bulk cargo shipment. Incidentally, modern airliners have 5,000s+ Isp from their turbofan engines. A 1950s era turbojet engine in full afterburner is more than five times as efficient as a chemical rocket, for comparison purposes.

My point is that if SpaceX develops true interplanetary transports with electric propulsion, then everything about what you want to do becomes far more practical to accomplish. Apart from orbiting a deep gravity well like Earth / Mars / Venus, chemical rockets are ultimately a technological dead end for interplanetary colonization.

If the goal is to use nothing but solar power, then we need true interplanetary transports, not chemical rocket upper stages trying to simultaneously fulfill the roles of reusable rocket upper stages, interplanetary transports, and landers, all at the same time. The optimal design for each of those tasks is at odds with the others. I've never seen any orbital vehicle reenter multiple times with zero refurbishment, for example, because those events are so extreme that they damage the vehicle's exterior, no matter the materials selected. Stainless was a very good design choice, but not even high grade stainless can withstand the temperatures encountered during reentry.

The most obvious choice is to design a large transport to get into orbit, which SpaceX has done, design another vehicle that stays in orbit and never reenters, and then to design a space elevator for Mars so that no additional reentry event is required to reach the surface. Then and only then will we have a practical interplanetary transportation solution that makes travel to and from Mars economical enough to colonize the planet and ship something back so that the endeavor pays for itself. At that point, we can afford to use commercial photovoltaic and battery technology, along with many other commercial technologies, because the cost of transport becomes similar to a first class airline ticket.

louis · 2021-05-19 17:08:39

Seems like you are in some sort of dream state where you won't accept that the the outfit most likely to get humans to Mars is Space X led by Elon Musk. Both Space X and Elon Musk have made it clear they will use PV power to set up a base on Mars. You just seem determined to ignore this rather pertinent fact - presumably because of some religious like devotion to nuclear power.

It's pretty obvious to me that Space X will eventually develop transfer vehicles from LMO and LEO but those are not a priority now for the first few Missions on Mars - they need to get big tonnages to the surface to enable the base.

kbd512 wrote:

Louis,
If we had rockets that were 10 times more efficient than current chemical rockets, then solar and energy storage starts to become feasible. If the rockets are 100 times more efficient, then as you've stated, nuclear probably isn't worth the hassle. That's why I stated that neither option is truly practical for building a city, if we're stuck with chemical rockets. More than 90% of everything we ship must be propellant using chemical rockets. Even freight shipped via airliners is vastly more practical than using chemical rockets, yet those are so costly to operate that typically small / light, high-value items are shipped by air, such as consumer electronics.
The correct propellant mass figure for delivering people and cargo to the surface of Mars is zero. We absolutely need a space elevator at Mars, which is feasible using existing Aramid fibers, not CNT or BNNT or anything so exotic. Going to and from Mars pretty much requires propellant expenditure, but the propulsion system needs to be a high-efficiency electric system of some kind, with a 2000s+ Isp, and 5,000s or more being highly desirable for practical bulk cargo shipment. Incidentally, modern airliners have 5,000s+ Isp from their turbofan engines. A 1950s era turbojet engine in full afterburner is more than five times as efficient as a chemical rocket, for comparison purposes.
My point is that if SpaceX develops true interplanetary transports with electric propulsion, then everything about what you want to do becomes far more practical to accomplish. Apart from orbiting a deep gravity well like Earth / Mars / Venus, chemical rockets are ultimately a technological dead end for interplanetary colonization.
If the goal is to use nothing but solar power, then we need true interplanetary transports, not chemical rocket upper stages trying to simultaneously fulfill the roles of reusable rocket upper stages, interplanetary transports, and landers, all at the same time. The optimal design for each of those tasks is at odds with the others. I've never seen any orbital vehicle reenter multiple times with zero refurbishment, for example, because those events are so extreme that they damage the vehicle's exterior, no matter the materials selected. Stainless was a very good design choice, but not even high grade stainless can withstand the temperatures encountered during reentry.
The most obvious choice is to design a large transport to get into orbit, which SpaceX has done, design another vehicle that stays in orbit and never reenters, and then to design a space elevator for Mars so that no additional reentry event is required to reach the surface. Then and only then will we have a practical interplanetary transportation solution that makes travel to and from Mars economical enough to colonize the planet and ship something back so that the endeavor pays for itself. At that point, we can afford to use commercial photovoltaic and battery technology, along with many other commercial technologies, because the cost of transport becomes similar to a first class airline ticket.

SpaceNut · 2021-05-19 18:27:11

Stainless steel is good enough for the near orbit to sub orbital strength that aluminum would not have for the side of the business trade for fast flights.....
These have nothing to do with solar for mars designing and of the delivery issues....

kbd512 · 2021-05-19 19:50:40

Louis,

There won't be any city of a million people on Mars using photovoltaics and chemical rockets. It's wildly impractical, and mandating the use of solar power only makes it an order of magnitude, or two, more wildly impractical than it would be with nuclear power. Weight matters, cost matters, simplicity matters, labor availability matters, and simple physics will remain undefeated by anyone's ideology. It's a bit like arguing over why we don't make aircraft out of Lead. No amount of insistence on ignoring basic math will ever change the math. That's why we don't have any cities on Earth that are entirely powered by photovoltaics and batteries, and why we don't ship cargo using chemical powered rockets.

louis · 2021-05-20 08:19:50

Well this can be tested for real can't it? Musk and Space X hope to get to Mars by 2024...if they miss that and hit 2026, it's still only 5 years away.

Although I am not a fan of the million person city concept, it's not impossible to achieve over 30 years from a technical feasibility point of view. 1000000 people over 30 years would be about 66,000 every two years. Let's assume children can be born on Mars, so maybe you only need 40,000 people every two years, with plenty of children being born during 30 years. At 50 migrants per Starship that would mean 800 transfer flights every two years plus 4,000 fuelling flights to LEO over maybe 4 months - the launch window. That would require about 40 Starship launches a day from Earth. Very challenging but not impossible, especially when you consider how many big aeroplanes take off from airports every day.

Regarding PV on Mars, we already have commercially available ultra thin PV weighing in at 2 Kgs per sq metre. For a 60,000 sq metre facility to power a propellant plant, that would be 120 tons. Add on maybe 3000 sq metres for powering the base (life support etc), call it 126 tons. Allow maybe 30 tons for electrical connecting equipment and 30 tons for a battery system - 186 tons in total for Mission One. That's a conservative figure - I would hope we can get that down.

kbd512 wrote:

Louis,
There won't be any city of a million people on Mars using photovoltaics and chemical rockets. It's wildly impractical, and mandating the use of solar power only makes it an order of magnitude, or two, more wildly impractical than it would be with nuclear power. Weight matters, cost matters, simplicity matters, labor availability matters, and simple physics will remain undefeated by anyone's ideology. It's a bit like arguing over why we don't make aircraft out of Lead. No amount of insistence on ignoring basic math will ever change the math. That's why we don't have any cities on Earth that are entirely powered by photovoltaics and batteries, and why we don't ship cargo using chemical powered rockets.

Calliban · 2021-05-20 16:14:24

The link below describes a real thin-film PV project.
https://www.power-technology.com/projec … rthinfilm/

The panels are a mere 8mm thick, which is impressive. They measure 2.2 x 2.6m and weigh 105kg each. That is 18.4kg.m-2 - about 9 times greater than the 2kg.m-2 that Louis described. And that is the mass of the panels, not including subsystems.

Last edited by Calliban (2021-05-20 16:17:20)

New Mars Forums

Announcement

#451 2021-05-15 18:11:12

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

#452 2021-05-15 19:48:10

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

#453 2021-05-16 15:15:07

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

#454 2021-05-16 17:59:59

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

#455 2021-05-16 18:41:13

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

#456 2021-05-17 11:48:47

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

#457 2021-05-17 13:26:35

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

#458 2021-05-17 14:35:11

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

#459 2021-05-17 16:34:24

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

#460 2021-05-17 18:20:14

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

#461 2021-05-17 18:27:52

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

#462 2021-05-17 18:34:32

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

#463 2021-05-17 18:39:37

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

#464 2021-05-17 18:51:43

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

#465 2021-05-18 14:27:57

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

#466 2021-05-18 18:17:40

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

#467 2021-05-18 18:25:39

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

#468 2021-05-18 18:54:09

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

#469 2021-05-19 09:27:08

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

#470 2021-05-19 11:59:53

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

#471 2021-05-19 17:08:39

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

#472 2021-05-19 18:27:11

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

#473 2021-05-19 19:50:40

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

#474 2021-05-20 08:19:50

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

#475 2021-05-20 16:14:24

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

Board footer