New Mars Forums

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.

What is mRNA? The messenger molecule that's been in every living cell for billions of years is the key ingredient in some COVID-19 vaccines

The structure of RNA is similar to DNA but has some important differences. RNA is a single strand of code letters (nucleotides), while DNA is double-stranded. The RNA code contains a U instead of a T – uracil instead of thymine. Both RNA and DNA structures have a backbone made of sugar and phosphate molecules, but RNA’s sugar is ribose and DNA’s is deoxyribose. DNA’s sugar contains one less oxygen atom and this difference is reflected in their names: DNA is the nickname for deoxyribonucleic acid, RNA is ribonucleic acid.

https://img-s-msn-com.akamaized.net/ten … 60&o=f&l=f

So no we are not becoming an alien....

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Brother did not come home and was being watched as there were 4 spots of pneumonia in the lungs but looks like they are still getting him out on Monday if things are still good.

My oldest son reports that an employee has turned up positive that he was trace notified of close contact with. He is a bit worried as to be understandable but he was wearing his mask and so long as the contact was not there it should be ok after isolating for the recommended 10 days from others.

I'm sorry to have noted this very interesting topic a bit later.
I've some question to discuss about birth rate in a martian colony where the life support system can sustain a limited number of people.

We like to imagine our colonies as brave free people settlements like the Galt's Gulch of Atlas Shrugged. But if our Mars Town life support can keep alive 1000 people and no one more, the birth rate will be very likely regulated by law: every time an old colonist die, a couple of young colonist will get the permission to procreate, to maintain constant population. If new domes are in construction, the colonists will get the permission to generate the right number of child to populate them, but no one more. And probably it will be also implemented some mechanism to equate males and females (i.e. artificial insemination with X or Y spermatozoa).

I know it seems very orwellian and dystopic, but what if air and food are not enough for all?

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.

Louis-
From my background in ranching, a figure that is almost universal for all mammals, according to the veterinarians, is 2% of the body weight per day in food consumption. That's a basic maintenance diet and not a weight gain or accounting for heavy work kinda diet.
That calculates to 1 kg of food for that hypothetical average human. I did the math several years ago on this website and calculated what supplies should be prepositioned before sending the Mars Direct style mission. This was before Elon came on the scene with his city of one million people. The number you mentioned earlier of ~2,400 grams sounds about right for a human doing physical labor.

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.

SpaceNut,

TSI at TOA on Earth is ~1,361W/m^2.

TSI at TOA on Mars is ~590W/m^2.

If an Earth-based PV panel is 25% efficient, then you can potentially obtain as much as 340.25 Watts of power.

To collect the same amount of power on Mars, your PV panel needs to be about 57.7% efficient.

340.25 / 590 = 0.576694915254237

Believe it or not, there is such a thing as a 57.7% efficient solar panel.  However, you'd better have your wallet ready, because they don't merely cost twice as much as the 25% efficient panels.  If your pockets are deep enough, then you can afford just about anything.  However, your average Mars homesteader may not have enough scratch to cover the increased PV cost after they pay a quarter million dollars per person for their one-way ticket to energy poverty to go live like Ted Kaczynski did.

Would a 57.7% efficient panel help reduce the crazy amount of surface area that you have to cover?  You betcha.  Every little bit helps.  The problem is that the PV array would still cover an area the size of a city, merely to supply a city of a million people, the size of a postage stamp by way of comparison, with power.  Beyond that, you have to store that power for at least 16 hours per day, because even 100% efficient panels don't produce measurable power at night.

I'd bet almost anything that the PV panels in the Bhadla array are 20% efficient commercial panels; the cheapest stuff the Indian government could get their hands on.  If the panels we use on Mars are more than double the efficiency of those used in Bhadla (46% efficient), then we're still talking about the biggest solar array ever constructed, with no other array on Earth even close to the same size, made from really expensive panels, with even more expensive lightweight backers like CFRP composite with a Nomex honeycomb core.  Damaging a single panel is literally akin to throwing thousands of dollars into a bonfire.  That's just to provide the air and water, but no food, no reserve power, and no power to make anything- despite the fact that construction in all active cities continues on into perpetuity.

Let's talk about weight, so that people who don't think we need to ship a million tons of cargo to Mars every year can begin to understand how ridiculous that idea truly is.

30% efficient GaAs cells from FullSuns:

4*8cm Triple Junction Gallium Arsenide Solar Cell

According to the documentation, each wafer weighs 3.8g +/- 0.2g.  Since we don't entirely trust Chinese quality control, we're going to round that up to 4g per cell.

1m^2 = 10,000cm^2

Each cell is 30.15cm^2.

Average fill factor per m^2 is listed as 85%.

8,500cm^2 / 30.15cm^2 = 282 cells per m^2

282 cells per m^2 * 4g per cell = 1,128g/m^2

1km^2 = 1,000,000m^2

1,000,000 * 1.128kg = 1,128,000kg = 1,128t

1 Bhadla = 10km^2 of active area (actual solar panels)

1,128t per km^2 * 10km^2 = 11,280t of silicon per Bhadla

50 Bhadlas * 11,280t of silicon per Bhadla = 564,000t of silicon

Now I understand why Louis wanted to build a PV factory on Mars.  Without it, this nonsense swiftly consumes every bit of a million ton cargo allotment.

If we have a 1kg/m^2 CFRP and Nomex honeycomb backer (4 plies of Toray T1000 cloth, two plies per side), then that adds another 500,000t.

Oh look, we've already used up more than 100% of our million ton cargo allotment.  We haven't included one lousy dab of Silver solder to connect the bazillions of individual silicon cells together, not one lousy meter of wiring to take the power to the base from tens of kilometers away, not one lousy power inverter, not one lousy transformer, nor one lousy battery to store any power so everyone doesn't die at night when there's no more solar power to be had.  Can anyone else do some simple math to figure out how much all of that wiring, the power inverters, transformers, and CFRP frames would weigh?  How about the batteries that store / supply 59.2GWh when day turns into night?

Delivering 11,580t for 30 of those 258MWe ThorCon reactors (includes the first batch of fuel, BTW) doesn't look so bad now, does it?

Heck, we can probably afford to splurge on Titanium containment cans instead of the cheapest carbon steel available, in order to cut that weight in half again with all the money we just saved on transportation costs.

If we have to deliver 78.2925t of fuel per year for, oh, I don't know, seven thousand years, that's about how long it would take for the weight of the Uranium and Thorium fuel to equal the weight of the Silicon we'd have to deliver to keep a million people alive.  Even if we transport it in special containers, we're still talking about several millennia of time for the weight of the fuel to equal the weight of the shiny sand.

Who else here thinks we might easily blow right past that 1,000,000t cargo allotment I proposed, by the time the weight of the rest of the machinery to keep everyone alive and healthy is included for construction of Mars City?

If anyone still wants to goof off with PV, then do it using locally-acquired resources AFTER we have a reliable power source in place that doesn't quit producing power every time the planet makes a half rotation.

louis wrote:

Feel free to join in. Kbd has arrived at a situation where he thinks a figure of 455 KwHes usage per household per sol of 2.5 people is a reasonable figure for a mature Mars colony. That's nearly half a MwH!

Louis,

Our summer time energy usage is 27.5kWh per day.  Our daily electricity usage is 5.5kWh per person.  If you divide by 24, we're using 229.2Wh/hr.  I go through your make-believe energy allotment in two weeks.

When you live in a ship or a submarine, you're living in a wind tunnel.  Those fans that move the air to keep you alive require a LOT of power, much more than the waste water treatment in point of fact, though not as much as the flash evaporators that provide drinking water from brine.

If we lived on Mars instead of Earth, 229W of continuous power is NOT ENOUGH to power CAMRAS and IWP.

Please let us know when that sinks in.

For GW Johnson re #82

Thanks for your taking that on!  Louis sometimes gets carried away in his enthusiasm.

Louis, thanks for all your contributions over the years, including the ones that inspire kbd512, GW Johnson and others to create some of their very best writing to deal with the situations that occur.

(th)