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Interesting article.
http://www.lpi.usra.edu/meetings/geomar … f/7044.pdf
Some extracts:
'The recognition of multiple lines of evidence for low geothermal gradients on Mars leads us inexorably to a planet where exceptional conditions are required to bring liquid water to reasonable drilling depths (e.g. 2 km for a light portable and automated drilling rig). Evidence of very recent volcanic activity should be sought to find intrusive centres less than 10^6 years old whole thermal halo has not decayed away.
At the same time, liquid CO2 is thermodynamically stable in the regolith at much shallower depths and models of Mars regolith must recognise the physical and chemical effects of this. Even if only small quantities are present at any one time, over geological time much of the regolith will have been flushed by liquifers of CO2 with its unusual solvent properties. The existence of liquid CO2 in the regolith represents an important energetic source of vapour for generating cryovolcanic features [6] and major density flows [7]. It also represents a significant drilling hazard in an environment when conventional drilling mud may be precluded due to cryogenic temperatures and to the expectation of severe losses into porous and brecciated regolith.'
This tends to suggest that the crust of Mars may be riddled with pockets of liquid or solid CO2 within as little as 50m from the surface. Due to the planets unstable axial tilt, large quantities of CO2 may have migrated underground during ice ages and may remain in impermeable traps to this day.
This could be hazardous to drilling, digging and mining on Mars. It could also provide an obvious source of power for future colonists. Liquid CO2 could be withdrawn from liquifers, heated above its critical point using stored solar heat and passed through an open cycle gas turbine. High pressure gas could also be used to power simple compressed air tools, which would be much easier to fabricate on Mars than electrically powered tools.
The implications for terraforming are obvious – much of the Martian atmosphere may exist as trapped liquid or dry ice underground. However, if terraforming does begin to increase the average temperature of the planet, trapped CO2 could prove hazardous. A pocket of liquid CO2 could build pressure until it exceeds the structural strength of the impermeable rock containing it. It would then release energy explosively. It may be necessary to seismographically detect these deposits and release the pressure before this can happen.
If we are indeed attempting to eliminate atmosphere loss through slow seepage to the surrounding environment, a polymer coating BOTH inside and out would seem prudent.
Understood. So we are talking about a polymer paint rather than a binder. This would appear to be prudent to prevent slow air loss and to minimise abrasion.
There is also the issue of water migration into the material and subsequent damage due to freezing cycles. Zubrin initially pointed out in 'Case for Mars' that this would tend to seal slow leaks. But it could also lead to frost shattering of the brickwork.
There has been speculation of the Martian surface being wet with saturated brines in some places. If so, it is possible that damp proof liners may be needed as well. Soil building techniques have been used successfully even in wet climates here on Earth. There are earth buildings in England and Wales that are centuries old. But the key to making them work is to keep them dry. The place that damp tends to enter is through the ground. When adobe is wetted, it loses half its strength and become vulnerable to abrasion.
There are a whole family of these initiators called VAZO-xx, where the xx = a temperature in degrees Celsius, and identifies the temperature required for initiation of the decomposition. They are manufactured by DuPont. We could probably find an initiator for a lower temperature polymerization, which would thereby be a less energy intensive process.
The bricks made with regolith simulant were apparently as strong as fired clay bricks, without any binder. Why would we use one if we didn't have to? The great thing about compressed soil components is that the materials are free.
In terms of living areas, I have been impressed by the extent to which furniture and interiors can be crafted out of moulded and rammed soil.
http://frommoontomoon.blogspot.co.uk/20 … ouses.html
https://www.google.co.uk/search?q=cob+i … D9YQsAQIKA
It would appear that in addition to the structure of a house, it is possible to craft seating, beds, cupboard space, work surfaces, sinks and even bathtubs out of compressed soil. This at least takes care of the immediate need for things like furniture within a habitat. The structure of a habitat can be created from rammed soil as well, provided it is sufficiently counter-weighted using rock and regolith against internal pressure. We would need a lot of glass to let light in.
I have no doubt that an early economy on Mars will be scaled down and simplified much as Louis suggests. It will be more manufacturing and less services oriented. It will help a lot that design services can be outsourced to Earth. I think food is going to be more of a problem that he supposes simply because relatively large pressurised, illuminated and watered areas are required to provide food for one person. Here in the UK, cities are relatively compact, but agriculture dominates about 80% of the landscape. And we are not self-sufficient in food. On Mars, all that land cannot simply be taken, it has to be made. To feed a million people, even with intense horticulture, would require about 100,000 acres. That's a lot of space that has to be covered with glass, pressurised and filled with manufactured air, water and soil.
Medicine can be simplified too. The areas of medicine that have had a big impact on life-expectancy are pre and post-natal care, surgery (mostly appendectomies and caesareans) and anti-biotic drugs. By the time most people need things like heart transplants, radiotherapy, chemotherapy, etc., they are usually old and usually they are history in spite of anything that doctors may try and do. There is a lot of debate over whether things like cancer treatment offer much benefit at all. One could make a good argument that 80+% of the benefits of medicine come from 20% of its spending.
I don't think there is any way around the fact that mining and manufacturing are going to require a lot of equipment and a lot of energy. But this is a question that would really benefit from a proper investigation. Maybe Musk could stump up the money for a few engineering PHD projects in this area?
Reminds me - these critters are pretty interesting too:
https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria
Iron oxidising bacteria - could we use them on Mars to make oxygen out of iron oxide? Don't whether it would be a less energy intensive method than others.
Cosmic rays must generate small quantities of oxygen and hydrogen through radiolysis of water in the Martian regolith. Maybe iron-oxidising bacteria are living in the regolith right now.
The Martian regolith is 0.2-1.0% perchlorate by weight. This is a powerful oxidising agent. Some bacteria have enzymes capable of breaking this down into free oxygen and chloride compounds.
This could be one admittedly dubious explanation for the free organics found on Mars.
This may be a key enabling technology:
https://www.theverge.com/2017/4/27/1543 … n-missions
If Mars soil behaves in the same way as the simulant, we wont need steel frames to manufacture these habitats. Just hydraulic rams and steel moulds, forming components from rammed regolith. These components can be manufactured to slide together or be bolted together.
This might provide a use for Louis's solar power, as regolith will be too cold to collect at night and the steel within the moulds too brittle at low temperatures.
Economies of scale do not relate to energy efficiency. They relate to cost .
Here's a typical definition:
"a proportionate saving in costs gained by an increased level of production."
The unit cost of producing electricity for a community of 1000 is higher if you install a 9GW plant as opposed to a 9MW plant. So in fact the usual economies of scale are reversed.
The reason economies of scale apply on Earth because there are very large levels of demand, and even within a static market, firms can steal market share through economies of scale. None of that will apply in the early settlement on Mars. "Fit for purpose" will be a better guide to efficient use of resources.
Antius wrote:Economy of scale applies everywhere. It doesn't cease to apply just because you are on Mars or because it isn't convenient to manufacture in large volumes. The fact that you don't need 9GW of an energy system doesn't mean you escape from the inefficiency of only making 9MW. It will always be less energy efficient to make something like solar panels on a small scale. There will be poorer utilisation of equipment, energy, material resources and labour.
Also, unless your facility can manufacture substantially more than its own weight in products over a realistic lifetime, you might as well import those products directly from Earth.
Louis, why do you think it costs more to manufacture small volumes? Could it have something to do with energy and human labour invested in equipment and facilities and the efficient use of them perhaps?
My point is that you cannot exploit economy of scale when you are manufacturing at a small scale. That is the same point you just made, but seem to missing the point I am trying to make. EROI calculated for solar power systems built on Earth, will not be applicable on Mars unless you are building these things on a similar scale, using the same processes under the same conditions. As processes are scaled down, they become inherently less efficient. This is why we don't make steel or cement in small scale batch furnaces any more and why power plants tend to be built in 100MW scales rather than kW scales.
I'm not sure what is meant in this context by 'self-sustaining'. If you mean having the industrial capacity and labour force to manufacture most of what is needed to survive and prosper on Mars with roughly first world living standards, then you are talking about a lot of people – 1million is probably optimistic. Imagine having to try and build something like a power plant or JCB in a colony of just a few thousand people. Making complex machinery requires a lot of equipment and lot of specialised labour. It isn't garden shed stuff. Extend that to all the products of modern society and the required number of people and capital investment becomes huge.
The problem is that we need a lot of technology and industrial capability simply to survive at the most basic level on Mars. Air, soil and water are things that would need to be manufactured. Surviving and growing food requires pressurised manufactured habitats containing manufactured air, soil and water. Manufacturing these things requires a lot of energy and a lot of equipment, much of it quite complex. A person cannot even venture outside without a spacesuit. This makes a Mars colony very different to a Greek polis. They were able to live simply at very low technology levels, because nature provided the essentials for free. All they really had to do was grow or harvest sufficient food and erect basic shelter. They could also trade with other polis and others nations such as the Phoenicians. Ancient Greek lifestyle was for the most part very basic – about as basic as human living can be.
Of course, not everything has to be manufactured locally. Much will be imported. If something is complex and relatively light, it will make sense to import it. Many products will consist of parts made on both Earth and Mars. Simple heavy parts made on Mars, complex parts made on Earth, design services provided by Earth, final assembly on Mars. The key thing in this scenario is having something valuable that can be exported to pay for imports. The more you can do that, the more you can import and the less you have to make for yourself. Given the transport costs it needs to be something with high value to weight. It would be advantageous if it were something that could be made or sourced without large amounts of capital equipment or specialised labour on Mars. Any ideas?
Economy of scale applies everywhere. It doesn't cease to apply just because you are on Mars or because it isn't convenient to manufacture in large volumes. The fact that you don't need 9GW of an energy system doesn't mean you escape from the inefficiency of only making 9MW. It will always be less energy efficient to make something like solar panels on a small scale. There will be poorer utilisation of equipment, energy, material resources and labour.
Also, unless your facility can manufacture substantially more than its own weight in products over a realistic lifetime, you might as well import those products directly from Earth.
Interesting ideas on soil creation. I think a big hurdle on Mars is going to be the 0.2-1% by weight perchlorate compounds in the regolith. That stuff is basically weed killer and is toxic to all animal life. There may be other salts that impair plant growth. Luckily all of these toxins are water soluble and can be removed by dissolving and then freezing. As the perchlorate is a strong oxidising agent it can either be broken down to yield oxygen or reacted with any organics we can find on Mars as a fuel.
Also, we discussed earlier the possibility of covering simple steel frames with regolith in order to create pressurised habitable spaces within depressions like craters. Here is a link to a shape that may be useful.
https://en.wikipedia.org/wiki/Pendentive
As the base has a square cross-section, these units could be stacked together to form continuous spaces. The central dome could have a large sunlight pipe in the middle protruding through the regolith to the surface. If the sunlight pipes have cross-sectional area equal to 50% of total enclosed area, and the area is located at the equator, then the average solar intensity within the habitat will be 750kWh/year. That's about the insolation that Scotland or Northern Canada receive. Enough for crop growth and abundant plant growth if temperatures are kept warm.
The problem with Mars made PV is that there isn't really any margin for inefficiency in the system - the EROI is only 7 under perfect conditions.
PV could be made on a smaller scale, but smaller scale ore processing and manufacturing is inherently less energy efficient. That's just the way it is. It's part of the reason why economy of scale exists. How much less efficient is difficult to say, but hand waving the issue is rather foolish since we don't know. If EROI were higher there might be room for inefficiency, but it is close to the limits of what would be workable under perfect conditions.
Simply assuming defect rates to be the same as Earth ignores the reality that you would be building panels under less than ideal conditions, with mass constraints on equipment and a more limited labour force. There is every reason to believe that this will effect quality and there is no reason at all to assume that it won't. Even Earth defect rates would be problematic, as they eat away at an already weak EROI.
A simple example: If the rejection rate of panels is 15% and the energy consumption of the process is 15% greater than on Earth, then an EROI of 7 turns into an EROI of 5.
Why would colonists tolerate low incomes and slow growth rates if they could do better? That's a bit like asking a man to walk instead of drive just so the world doesn't have to be burdened by his car.
Also, why would you assume a colony to have 50 people? Musk is readily discussing a city of 1million established in less than a century. It is hard to imagine this happening without a lot of Mars manufacturing and a high-EROI energy source to power the expansion.
I love the image. Is that a maglev train in the foreground?
On the topic of solar: EROI becomes important when we start making things on Mars. At that point, we are using up whatever finite resources we brought from Earth in the hope of leveraging them into something more productive using Martian resources. For early missions it will matter less, because those missions will be entirely subsidized by Earth. As things scale up into full scale colonies, more and more of what is used on Mars must be manufactured locally. To get high rates of growth, we need high EROI so that we can invest energy in new infrastructure, rather like the city in that image.
Poor EROI of manual pre-industrial agriculture was a big part of the reason why mediaeval living standards were so poor and remained so for so long. There was very little surplus energy to support non-agricultural classes and hence scientific progress was slow. There was no excess wealth to support infrastructure development. It was the development of global trade by Britain and Europe and the harnessing of fossil fuels in the former that provided the energy surplus needed to start the industrial revolution. It just wasn't possible until the discovery of controllable, high-EROI energy sources. It is no accident that modern Western living standards are starting to decline as the EROI of fossil fuel energy sources starts to decline.
If a Martian civilisation is going to grow and prosper in a harsh environment, then high EROI energy sources are key. Without them, there is never enough surplus wealth to expand infrastructure.
Why would colonists be manufacturing Li-Ion batteries? We mainly use them on Terra for purposes where a high power-weight ratio is needed, such as vehicles and portable electronics. How would it look if they used NiMH, or Nickel-Iron?
Possibly. On Earth deep cycle batteries tend to be lead acid. They have lower cycle efficiency and lower mass energy density than Li-ion. But they are obviously more cost-effective none the less. Not sure how they compare on an embodied energy basis.
The annual insolation at the Martian equator is 1400kWh/m2. Thats about the same as southern France or Northern Italy. Substantially more than the UK which averages about 850. In fact, England during winter has about rhe same insolation as the moons of Jupiter. The estimate for Mars doesn't account for dust storms. I have subsequently revised upward my estimate of atmospheric transmittance to 84%. But it varies substantially from place to place and season to season.
I have completed an EROI analysis for thin film amorphous silicon cells manufactured and installed at the Martian equator. It's actually better than I expected. Without storage, EROI is about 10. With storage in Li-ion batteries, total EROI works out at 7 over a 25 year life. For storage in methane-oxygen and backup energy generation with combined cycle gas turbine, it works out at just over 3. This is largely due to the poor efficiency of energy storage in this way, which is about 18% efficient. So this is not a good option for storage of excess solar energy unless you really do need a portable liquid fuel.
I will provide more details on workings and references tomorrow if time allows. For now, here are a few caveats:
1. The EROI analysis applies to the equator. The further away from the equator the plant is located, the worse the EROI, because annual insolation goes down and the array must be sized to provide sufficient power over winter, which increases its size.
2. I have assumed annual degradation rates of 1% which is typical for thin film in sunny parts of the Earth. However, the ultraviolet environment on Mars is a lot harsher and temperatures can swing by as much as 100 Celsius in 12 hours. There is also substantial charged particle background radiation, although the effects of UV will probably be more significant.
3. I have assumed that all modules are fit for purpose, without rejections and that none of the panels require replacement or deep maintenance in 25 years.
4. I have assumed that panels can be made on Mars with the same efficiency, the same quality control and the same embodied energy as here on Earth.
5. I missed out the embodied energy within the sabatier plant and storage tanks in the methane-oxygen scenario. So actual EROI may be less than calculated, although I suspect embodied energy is dominated by the panels.
My overall impression is that it could be made to work with an efficient Li-ion battery solution, assuming these can also be made on Mars to the same lifetime energy investment, longevity and efficiency as those on Earth. This is quite important, because the EROI of PV is weak before storage. The storage solution must have low embodied energy and high efficiency to keep EROI within workable limits. Likewise, the conclusion depends on the other caveats above working out the right way.
Louis makes the point that high EROI is less important on Mars because colonists will be working age and without dependants. That is partially true. What low EROI actually translates into is expensive and less abundant energy, lower labour productivity, higher prices paid for goods - in short, less wealth. He is correct that that situation is easier to tolerate if you don't have to support a family and if things like invalid and prison populations are small in proportion. However, it is difficult to see that situation being sustainable for very long. It is also difficult to see how a weak energy economy is going to be a small matter for a growing population on a harsh planet. These people need to grow their infrastructure into something that new people would want to move to and they need to scratch out a living in an environment that doesn't provide for free a lot of things that are free on Earth. No one would want to live like that if it means living in poverty on a desert planet. For Mars to become the New World that America was in its golden age, it needs high rates of economic growth and better living standards that the ones that people can find on Earth. It needs to be more than Siberia with a red sky.
It is noteworthy that manufacturing PV on Mars only makes sense if the plant can make at least its own weight in power systems in a reasonable investment window (20 years?). Otherwise you may as well import your power source from Earth.
Louis is dodging the facts again, hoping he can 'argue' solar into a better position…ha ha ha! Maybe god will smile on his efforts here and change the laws of physics to make it so :-) Life has an unkind way of stamping all over pet ideologies.
The EROI of an energy system on Mars would be less than 1, i.e. negative energy balance, if the energy produced by the plant over its lifetime, after losses in transmission and storage, is less than the energy invested in creating and maintaining it. In reality, if EROI is less than about 3, an energy source cannot be economically viable because of losses in end use and the need to reinvest energy to maintain the energy system. There is nothing insubstantial or theoretical about it, it really can and does happen and it is well reflected in poor economic performance of some energy sources. It is why corn ethanol will never supplant petroleum without subsidies.
Energy economics is a fairly good proxy for determining the real economic performance of an energy source. But EROI on its own is not the whole story. Just as important are ‘energy payback time’ and ‘energy rate of return’. Some energy sources can do relatively badly on EROI (within limits), but will still float economically if ‘energy rate of return’ is good. Natural gas projects are a good example of this, as build times can be very short. Even though fractured shale wells have monstrously high depletion rates and poor EROI, they can be profitable, because they deliver huge energy return during the first year. This can be where big nuclear projects fall down, because in the present regulatory climate it can be 10 years or more between first work on a project and electricity reaching the busbars. EROI can be excellent over the life of the plant, but rate of return could be mediocre over the investment timeframe of 20 years, because the first 10 years produce nothing. The French have had a successful nuclear programme largely because build times were kept to within 5 years, as they focused on developing a common design, often with multiple units on a single site, which benefited from a learning curve and regulators were happy to do their jobs without halting the project.
Reducing build times is why most countries in the know are now developing smaller modular reactors that can be built in factories and assembled in weeks or months. It is no accident that some of the first reactors to be built in the western world were also relatively cheap. Of course on Mars, reactors will be imported at first, will be very compact and modular and will be operating within days of delivery.
In a reusable transport system, the energy cost of delivery is going to be small beer, because of the overwhelming energy density of nuclear fuel. If a multi-megawatt reactor core provides 200W/kg and it costs 100MJ/Kg to push it to Earth escape and TMI, it will repay that delivery cost in a little less than six days. If the real energy cost is ten times greater, the energy delivery cost is repaid in about 8 weeks. Compare that to a core life that could be 5-30 years, depending on design.
Remember that there is nothing ‘green’, ‘friendly’, ‘pure’ or ‘morally good’ about any energy source that man has ever developed. They all rape the natural world in one way or another and through their action, allow man to harness nature’s capital for his needs. Some are worse than others, but there is nothing inherently good about any of them. In fact ultimately, the only green thing any human being can do is die. Isn't that a depressing thought.
There is no reason why the batteries can't be built on Mars. As for Martian nights, why would you have the batteries outside? I presume they would be in a specially designed hab.
kbd512 wrote:To give everyone an idea of how much of a weight difference there is between a Tesla PowerWall and an ORU, the PowerWall weighs 264lbs and has a 13.5kWh usable capacity. Each ORU weighs 430lbs, or 518lbs with the heater plate, and have a capacity of around 14.8kWh. None of these Tesla PowerWall or PowerPack batteries will ever be subjected to the kind of gravitational and vibrational loads that a space launch and reentry will produce, nor subjected to frigid Martian nights, so it's not a very good reference point.
If you are talking about using Mars built batteries to store energy from Mars built PV, then I would suggest that this is problematic and should be kept to a minimum. The problem is Mars built PV would have long energy payback times before the embedded energy of the battery systems and storage losses are taken into account. When those things are included, the balance could begin to go negative, I.e. you get less out than you put in - you do not recoup your energy investment before the lifetime of the systems is reached.
There are a lot of things that have to have reliable 24/7 power. A lot of high temperature processes like aluminium or silicon manufacture would find it very difficult to cope with intermittent power because if feedstock solidifies in crucibles and electrolysis cells, it does a lot of damage. In those cases, you need power around the clock and there is no escape from that.
In some cases 24/7 power is desirable but not essential. Examples might be machine shops and computer terminals. Running these things for 6 hours per day would be an inefficient use of expensive assets, but you will not damage them by using them in this way. You could live like that if there were no choice. It would mean accepting lower rates of return on capital equipment and lower industrial growth rates, but in principle it could be done. Likewise with human living. Some high energy loads such as washing clothes, heating water, cooking food, etc, might be programmed to switch on when power is available. It is less efficient in some ways, but could be made to work.
There are some instances where energy end use can be genuinely flexible with only a small penalty. Pumping water for example. We might pump water into header tanks for a few hours a day, and it might not matter so much if power is not available continuously, as we can store a days worth of water in a tower. Because it is easy to store heat in cheap energy dense materials, any end uses that require hot and cold can work on intermittent energy by adding thermal capacitance. As always there are costs involved in doing this, but it can be made to work.
To reduce energy payback times on a PV system on Mars, it is important to use the power when it is available, in applications where this is at all possible. That way, you minimise the need for energy expensive energy storage. Also, it would make sense to try and match the voltage output of the panels to the devices that consume power. That way you minimise energy losses due to power conversion. Keep transmission distances short and try and run as much as you can on 12 or 24 volts DC. For things like lighting and computing that is easy. For high power applications, the current starts getting scary, you end up needing thick conductors (more invested energy) and local resistance generates a lot of heat, potentially causing fires. But people have made this sort of solution work in the past and low voltage DC networks are not that uncommon. The key thing is to keep transmission distances short and to size conductors for the intended current. So basically, heavy loads need to be no more than 100 feet from the panels.
I designed a man cave outhouse to run entirely on 12v DC. I got around the transmission problem by using the RSJs in the building structure to conduct the power. These had such high cross-section area that internal resistance was small even at very high current levels. It needs to be because a 1.2KW load draws 100 amps! Because voltage is so low, a thin layer of paint and ordinary masonry has enough resistance to insulate the rsj against lea j age. It should work, but it will be some time before I can build the thing and test it.
There are no free lunches really. If we try and use power without storage, the EROI of the solar power system may improve. Unfortunately, the rate of return on other capital equipment goes down because you can only run it for perhaps a quarter of each day. However, the wear and tear on equipment is usually linear to operating hours. Although rate of return would be lower, total return should be the same over a longer time. You just have to wait longer getting things done and people would need several jobs. They do high energy tasks when it is available and low energy tasks when it is not. The same with recreation.
The pillar structure that you mention would be the most easily achievable from an engineering viewpoint. You could start by finding a depression such as an impact crater. Within the crater lay down a series of square steel lattice domes, supported by a vertical leg in each corner and with a sunlight tube some 10m tall extending upward from the middle. Cover the domes with rock and soil to a depth of 10m and provide gravity stabilized berms at the outer edges. You can do this by using a front end earth mover to simply push surrounding rock and regolith onto the lattic structure until its about 10m deep. Pressurize with air and then move in. You could paint the ceiling blue if you wanted to.
If sunlight tubes account for say 50% of the surface area of the steel lattice, then there would still be sufficient light for crop growth underneath. The steel supports at the corners of each dome could serve as lateral stabilizing supports for adobe buildings. In these, you would have accommodations, commerce and factory buildings as required. Solar panels could be placed on the surface between the skylights with cables passing through the regolith and rock layer into buildings directly beneath. If cabling is kept relatively short in this way, buildings can be wired for 24v DC without the need for transformer and inverter losses from the solar panels.
The sunlight pipes would have convex glass dome covers on the inside to resist internal pressure. At the top side, a thin glass cover would be in place to prevent dust accumulation within the pipe. The pipe itself would be coated in aluminium to allow light to pass down the tube. The inner skylight and dust cover would both absorb infrared light. This, and the thick layer of gravity stabilising rock and regolith would help keep heat in during the freezing Martian night.
If each steel lattice is say 50m high and 30m between its legs, then individual frames can be lifted in by crane and the legs braced together and to neighbouring lattices for stability. As the skylight is about as wide as the sunlight tube is tall, only those cosmic rays that enter the aperture at less than a 30 degree angle will make it through.
A lattice dome some 30m wide would cover some 900m2. To cover 1km2, some 1100 lattice domes would need to be stacked in square configuration. Habitats could be divided into cells by separating them with earth berms and having tunnels run through them, much as Louis suggested. This would protect residents against catastrophic depressurisation and fire.
Mars is...too far away to function as a human colonisation target at present technology sets.
Really? Really?? Really???
Thankfully we don't have to argue the point, we just have to await Musk honing the present technology and getting humans to Mars. ISRU energy, radiation protection, space medicine, rocket technology, orbital assembly, hab construction, water recycling, life support technology and Mars mapping are all well advanced. All we need is focus and money.
Afraid so. I'm not saying it's impossible for Musk to achieve what he is setting out to do, just that it is much more difficult getting the ticket price down to $100,000 or even ten times that. The spaceship only gets used once every 2.5 years, effectively only a dozen times in a 30 year life. The moon is close and it is much easier to build up the sort of transport scale economies that aircraft enjoy here on Earth. So colonisation of the moon is certainly much easier in the near future (100 years) than colonizing Mars. Whilst I would like to see it happen, I don't think Musk is going to have the money and support to do this. The moon offers a halfway house that is far more achievable.
As far as Elon Musks ITS business model is concerned, Luna has some very strong advantages over Mars as a first colonisation target.
The first and largest advantage is its closeness to Earth. This would allow the space ship to be reused once every several days rather than once every two years. That is clearly a huge economic advantage, as you get a lot more out of each ship. You can also get away with taking far less consumables and providing less cabin space, as people will only be on the ship for 3 days. So, a lot more people carried per trip and a lot more trips per year. If the ticket price is the same, a lunar transport system would be hundreds of times more profitable.
Secondly, with a lunar based target, a lot of the propellant used to refuel the ships in orbit (all of the oxygen) can be sourced from the moon. That reduces the number of tankers that you need. Transfer of inert cargo can rely on solar electric propulsion. The sun of course has over twice the energy flux in the Earth-moon system. Much of the surface construction on the moon can be carried out via teleoperated robots controlled from Earth. Lastly, a moon colony is far more useful in the development of facilities and colonies in high Earth orbit.
Whilst Mars is a more interesting place with more abundant resources, it is too far away to function as a human colonisation target at present technology sets. That said, the apparent lack of mineral resources on the moon really makes it far less appealing.
I think you make my point for me. You would rather send a 400 tonne nuclear reactor to Mars, than send 400 tonnes of anything else, whether it be fertiliser, 3D printers, robot production lines, laptops, computers, furnaces, kilns, communications gear or anything else that is going to accelerate Mars's industrial development. You'd rather Mars was kept on a drip feed from Earth.
That's a rather daft statement. The reality is that you need all of these things from Earth until you can make them yourself.
Your following claim is simply not true. Or did you mean "after" rather than "before"?
"Nuclear reactors still cost less than PV farms before the coal or gas power plant is included in the cost paid to provide equivalent capacity. "
Do you accept that if the price of PV and energy storage continue to fall that at some point they can beat nuclear, coal and gas at providing utility scale electricity? Just wondering, because sometimes it sounds like you think there is a law of physics preventing that.
Unlikely. There have been some impressively cheap PV projects in the past several years largely because the Chinese invested tens of billions of dollars in state owned enterprises to produce PV for their domestic market. The market in China has crashed and they are now dumping these panels on the global market at less than their manufacturing cost.
http://fortune.com/2016/09/14/china-sol … roduction/
The Chinese tend to do things like this to keep their population in work. It is inefficient, but that's Communism for you. As long as the global market remains small the Chinese can keep selling these things at a loss and can trade them for real resources in other countries.
On top of this, renewable energy subsidies are now mandated by law in Western countries. In most places, utilities are required to purchase increasing proportions of electricity from renewable sources. The cost is passed on to customers and tax payers through a complex set of mechanisms.
http://www.cnsnews.com/news/article/bar … lectricity
Solar advocates tend to obscure or ignore these inconvenient facts. Recent declines in price have more to do with market distortions and politics than technological advancements. They remain possible only as long as demand is relatively small.
One must also consider that the relative price of energy sources varies from place to place. A small country or isolated region with few domestic fossil fuel resources and little in the way of technical expertise may indeed find it cheaper to import a solar power plant from China than a continuous supply of natural gas from Qatar. That doesn't mean that solar power is cost competitive with fossil fuels or nuclear energy in large markets. It means that a subsidized (dumped) commercial product happens to have a short term, local advantage in that place.
Ideological advocates of renewable energy tend to capitalize on local anomalies like this and use them to suggest that a new age is upon us. But the devil is in the detail that they purposefully leave out. Political ideologues will always find ways to advocate things that they believe in. It is often difficult to see propaganda for what it is. But no amount of ideology, propaganda or manipulation can turn a bad solution into a good one.
This is interesting: http://www.lpi.usra.edu/meetings/geomar … f/7031.pdf
We would need about 1000 tonnes of carbon to build a small Magnox gas cooled reactor (150MWth) on Mars. To make that much graphite using manufactured methane pyrolysis, would take about 17MW-years of electric power. A source of methane (or other organics) on Mars, would cut the required energy investment by at least 90%.
For those interested:
https://thebreakthrough.org/images/pdfs … _Cheap.pdf
I bet Texas's population density is somewhat lower than Denmark's...
As to Texas's suitability for wind energy...
https://www.ecowatch.com/6-reasons-why- … 96525.html
I guess it depends where you are coming from.
For the purposes of this discussion, I am not denying that nuclear energy can produce a lot of energy on a small footprint. But it is also very, very expensive. We are having to guarantee the price of nuclear in the UK for future installations at over
Our next nuclear power station could cost £37 billion for 3.2 GW of electric power. So about £10 billion per GWe.
https://www.theguardian.com/uk-news/201 … up-to-37bn
But what is going to happen to the price of solar power and energy storage over the next three decades? All the signs are that both will continue to fall rapidly.
Nuclear power reactors are really only as expensive as we choose to make them. They are inherently simple things – basically just boilers and they have very high power density. If they are costing £10billion/GW it is a sign that we as a nation are doing something badly wrong, not that the concept of generating energy from fission is inherently expensive. Part of the problem is that no one has built a nuclear reactor in the UK for over 20 years. So Hinkley is essentially trying to start a whole new industry. Our regulatory regime is also very efficient at increasing build times, which really pushes up the cost of a nuclear reactor.
Take a look at the link below. The US was able to build nuclear power plants for as little as $500/kW back in the 60s and 70s. The South Koreans and Indians are able to build for $2000/kW today. The French built the majority of their fleet at <$2000/kW. By that measure, Hinkley C should cost £5billion.
Bottom line is, if someone is trying to rip you off charging you above the odds for a new car, would you conclude that all cars are expensive, and therefore it’s better to buy a horse, or would you take steps to find a cheaper car?
https://thebreakthrough.org/index.php/p … r-reactors
The issues in relation to Mars are far less about cost and much more to do with suitability, flexibility and reproducibility. My view is that within ten years, a Mars settlement could be producing all its power from ISRU manufacture of PV panels. It could also store all the power it needs as methane/oxygen, manufacture methane/oxygen generators, and produce chemical batteries in abundance. A 1000 person settlement would have no problem generating say 20 MWs constant using solar as the power source. That might require say (guesstimate) 2 million sq metres of PV panel. If the settlement can produce panels at a rate of 400 sq metres per day, that means they could produce that many in under 14 years. Obviously they don't need to achieve that rate immediately.
We have already gone over why Mars built PV doesn’t work very well. It would have very long energy payback times and energy storage makes that problem even worse. If it were a simple matter to manufacture solar panels using 3D printers then it would be widespread here on Earth and established PV manufacturers would be going out of business. The reality is that PV manufacture is a capital intensive and energy hungry industrial process. Making your own at a hobby level is rather like trying to make your own microchips.
I have no doubt that a colony will make use of Mars built solar power in places where its modularity make it useful, but the poor energy rate of return makes this a bad investment for bulk power supply. For a colony on Mars, the most favourable energy investment will be the one that gives them the most energy back, the most quickly for the smallest amount invested. That much should be obvious. It should also be obvious that the highest rate of return comes from the most power dense systems. This is just simple physics.
What actually happens is that Denmark generates renewable electricity equivalent to 60% of its consumption, and then dumps it into the electricity grids of Scandinavia and Germany. It then imports large amounts of electricity power from Scandinavia and Germany at periods of high demand. It can do that because it is relatively tiny and they are big. Another interesting but scarcely mentioned fact is that Danish electricity production from other sources is collapsing. This makes the renewable contribution look bigger, but the reality is that the Danes are importing more.
https://notalotofpeopleknowthat.wordpre … ind-power/
It is theoretically possible to balance the grid internally using flow batteries, thermal storage, CAES, etc. But at what price? Denmark already has the highest electricity rates in Europe, followed closely by Germany. Wealth is basically the use of energy to manipulate matter. Expensive and scarce energy ultimately translates into less wealth.