Calliban Postings including links to notable contributions

tahanson43206 · 2024-09-19 10:11:35

For Calliban ... FriendOfQuark1 sent an inquiry about the problem of heating inside a hollowed out asteroid...

I'm sort of warming to the problem Caliban perceives. It isn't an issue for the oilfield. And we don't spend much time (any?) on what the thermal permeability of "rock" (a broad term!!!) is.
I'm a little perplexed though why Caliban perceives a future where things are thermally inefficient. Say a nuclear powered craft produces 1,000 units of power/heat. If the ship is only able to convert 3% of that nuclear heat to "work" you would heat up your "rock" pretty fast. Don't we expect to convert, especially in a more technologically advanced future, a much larger percentage of the theoretical maximum to work? Surely, there is an efficiency level vis-a-vis the volume of 'rock' where the amount of heat the rock radiates out to space is in parity to the amount of heating is being imparted? E.G. surely the hollowed out asteroid radiates a non zero amount of internal heating to the "aether"....?

For Calliban ... I'm looking forward to your answer .... I am hoping you won't be distracted by the efficiency question. I'm hoping you will concentrate on the insulation that an asteroid would provide that would prevent a spacecraft from radiating thermal energy to space.

(th)

Calliban · 2024-09-19 11:30:08

I'm not sure where 3% efficiency comes from. The efficiency of a heat engine has relatively little to do with how high-tech society is. It is a function of the temperature difference between hot source and cold source. Devices can be optimised with better engineering. But the upoer limit to efficiency is set by the Carnot equation.

Regarding geothermal. Heat has accumulated within deep rocks due to some combination of internal radioactive decay (usually mW/m3) and conduction from the mantle. When heat is withdrawn from a unit volume of rock, its temperature will decline. Heat will enter the rock both through internal radioactive decay and conduction from surrounding rocks. Both processes are relatively slow. The first is limited by the half life of radioisotopes within the rock. The second by the temperature gradient and thermal conductivity of the surrounding rocks. But in practical terms, geothermal energy is a form of mining. The resource is finite in human timescales, though it may be relatively vast. Once a volume of rock is drained of heat, it will take a long time to recharge through conduction and radioactive decay.

Regarding the asteroid question, so far as I understand it. Yes. An asteroid in thermal equilibrium will radiate as much energy (in infrared) as it absorbs from the sun. Internally, there will also be some heating from decay of radioactive elements in the rock. So we would expect all asteroids to be warmer in their centres than in their outer crust. The larger the asteroid is, the warmer its centre will be.

Last edited by Calliban (2024-09-19 11:54:21)

tahanson43206 · 2024-09-19 13:37:54

For Calliban re #127

Thanks for taking a first cut at the multiple questions from FriendOfQuark1....

The question about the hollowed out interior of an asteroid came up because I tried to quote what I remember from your posts on the subject....

I had proposed that a spacecraft might dig a cave for itself inside an asteroid to gain protection for severe radiation.

In reply, you warned that the interior of such an asteroid would not meet the needs of the spacecraft for cooling. My recollection is that you warned that the spacecraft would cook itself because the asteroid would not accept the thermal radiation from radiators on the ship.

I've been hoping you might develop that idea further. If you have lost track of that conversation, please let me know and i'll go looking for it.

The problem would presumably be worse if the asteroid is a rubble pile, because thermal energy would have an even harder tune flowing through a rubble pile.

(th)

Calliban · 2024-09-19 14:29:18

That would depend upon the thermal conductivity of the rock, the thickness of the rock and the temperature difference between the surface and the spacecraft. It also depends upon time - does the system reach thermal equilibrium, i.e a stable temperature gradient? Lets assume it does.

This reference discusses thermal conductivity of crustal rocks. This ranges between 2.5 - 4.5W/m.K. Lets assume the latter.
https://onlinelibrary.wiley.com/doi/10. … 21/6630236

Suppose the surface of the asteroid is at a temperature of 200K (-73°C). Suppose your spacecraft is at a temperature of 300K. How much heat would a 10m thick layer of rock conduct away?

Q=kAdT/dX = 4.5 x (300-200)/10 = 45W/m2.

So I would guess it could work, provided you are not too deep within the asteroid. If the rock thickness can be reduced to 1m, then thermal conduction increases to 450W/m2. It does impose limits on the practical power generation for the spacecraft.

The problem disappears altogether if the spacrcraft can transfer heat to a radiator on the surface of the asteroid, via a fluid containing pipe. If that can be done, then limits imposed by thermal conductivity of rock are obviated.

Last edited by Calliban (2024-09-19 14:33:22)

kbd512 · 2024-09-20 10:41:56

This fixation on energy efficiency is debilitating to the very concept of cleaner energy. There has never been an exemplar energy efficiency increase accompanied by a net reduction in energy usage related to the newer and more energy efficient technology. It doesn't matter if we're talking about lights, engines, computers, or higher strength-to-weight ratio materials. Increasing energy efficiency is not wrong as a concept, but it always produces the exact opposite of the intended result. If we make something more efficient to use, the end result is that we use or consume far more of it, but never less.

We burned whale oil. That was highly inefficient, expensive, and we rapidly ran out of whales. We created cheaper incandescent lights, which produced many more lumens of light per Watt of energy consumed, in comparison to whale oil, because they were way more energy efficient and we had a very large coal supply to feed into the steam boilers to produce electricity. In aggregate, because there was no shortage of coal to burn to generate electricity to power those incandescent lights, net energy consumption associated with lighting drastically increased. We invented LEDs and other semi-conductor technology after WWII, which were in turn more efficient than incandescent lights. Unfortunately, they required far more energy input to make each bulb, an electronic vs electrical device, and now everyone leaves their lights on 24/7. No net energy consumption decrease was achieved.

I hear we now have laser-pumped LEDs, which are purported to be 2X more efficient than plain old semiconductors at producing light. It's a mash-up between halogen or fluorescent tech and LED tech. Pretty soon everyone and their dog will have their homes lit up like neon road signs, at all times, from all angles. People will buy even more of these new lights, which require more energy to make than ordinary LEDs since they require another electronic device- a fiber laser. Per-device energy consumption seems very small, and per device, it truly is. We'll put them up everywhere because they don't use much energy. Similar to AI and data center based computing, we'll inevitably go nuts with this, because that is our nature. No net reduction in energy consumption will be achieved. We'll use vastly more light at all times, even when not required or providing material benefit, which is a fine outcome if you actually want more light. Unfortunately, you'd be foolish to believe that any energy will ultimately be saved by our vastly superior laser-pumped LEDs. Incontrovertible historical evidence indicates that all historical energy efficiency increases were also accompanied by dramatic increases in energy consumption.

We made natural gas energy so efficient that we used it to replace coal. Not only do we burn more natural gas now, we burn so much more that our CO2 emissions are markedly higher than they were when we were mostly burning coal, because there are 5X more units of energy output for every unit of energy input. The brilliant blue flame of natural gas may be far more aesthetically pleasing than the sooty exhaust of coal, at least to some people, but superficial appearance is as far as that goes. We are, in point of fact, using so much more, that CO2 levels are increasing faster, not slower, as we burn more gas instead of coal. You can argue that the air is still cleaner, because it is, but reducing CO2 emissions was the stated end goal behind using more gas vs coal. On that metric, the "energiewende" was a miserable failure.

In actual practice, efficiency is a misnomer. That word actually means we discovered a new way to use more energy. What is some specific newer and more efficient energy technology useful at doing? That is the proper question to ask, because we will use more of it, because we can, at least until we cannot. Electricity is very efficient at consuming more and more energy and energy intensive materials. The more electrical and electronic devices you have, the more demand you'll create for additional electrical and electronic devices. In practice, it's an exponential feedback loop. What's the one thing you cannot do when your energy demand continually increases? You can never stabilize consumption rates. If something costs less money, that's ultimately because less energy went into making it, which means more energy / money remains for using it, which means it will see more use.

If we're not actually doing what we claim as the primary reason behind what we're doing, then why do we need to pretend to do it?

Why is it so difficult for us to be honest with ourselves about what we're actually doing, as opposed to what we intended to do?

The thermal systems that Calliban has come up with are all about actually consuming less energy while still satisfying the basic "need" for something (cooking, warmth, food stage, etc).

If they look somewhat unfavorable when compared to something else, then we should come to terms with the fact that natural energy systems, which are simplistic yet durable energy generating and consuming designs by necessity, don't have the same characteristics as higher-energy systems. This is a feature, not a bug.

Heating up crushed rock using direct sunlight might look inefficient compared to, say, a giant wind turbine sending electricity directly down a wire. The difference is that the rock was scooped off the ground, crushing it was the most energy intensive thing we did with it, and because we sourced it locally, we didn't need to ship vast quantities of materials around the world several times so they could be made or assembled in some specific factory that did that one specific job better than anybody else. Let's say that the end use for the energy is a water desalination plant because there's not enough ground water. There are lots of ways to desalinate water, but you can use reverse osmosis or you can flash evaporate it. Either way, the end result is fresh water.

The wind turbine method requires carbon fiber, rare Earth elements, magnets, Copper, Aluminum, control microelectronics, step-up and step-down transformers, a power line, electric motors to power the pumps at the reverse osmosis plant, filters and filter media, and the list goes on. It may or may not theoretically require less energy, but in point of fact if we did that at scale, then it's going to ultimately consume more energy than direct heating of water using concentrated sunlight.

Using the direct sunlight / solar heating method, we have a giant thermal energy store, essentially a pit of crushed rock. We first heat the water as it passes through that giant thermal energy storage pit. The water flows through powered by water pressure, possibly a trompe or possibly steam from the second stage of the plant. The second stage of the plant uses mirrors to flash evaporate the near-boiling water as it enters. Cold salt water is then used to collect the fresh water in the condenser. Very little in the way of moving parts or specialized high tech equipment is required, because heat and pressure are doing the work. There's just not a lot of sophisticated bits of technology to break, short-circuit, or otherwise wear out. As a result, this sort of plant can keep producing fresh water, potentially for centuries. In contrast, many of the components in the high tech method won't last for a year before they need to be replaced or substantially refurbished. Incidentally, this also basically describes how a natural aquifer works. It's an above-ground variant of an aquifer, but it's doing the same thing.

If either method is getting the job done, why are we devoting more energy and more technology to do what nature and natural materials already do at a scale we've yet to match?

Isn't our apparent lack of progress, relative to nature, a sort of "clue" that what we're attempting to do with high technology may be efficient by one arbitrary metric, yet still vastly inferior to the natural way in which high salinity or brackish water becomes fresh water when filtered through an aquifer?

I think it's worth consideration.

tahanson43206 · Yesterday 13:27:21

For Calliban re new Topic about water/fluid goods transport...

I'm hoping you will actively develop this idea.

The NewMars archive is bulking up with great ideas you've published.

From my perspective, many of these could become thriving businesses and some could become entire industries.

While I don't pretend to be qualified to participate in the topic itself, I am hoping I can offer encouragement from this perch off to the side.

To begin with, there needs to be a market where slow movement of material over perfectly flat terrain would support your venture.

As it happens, the planet's oceans and lakes, and even some rivers would be ideal locations for your concept.

Vast amounts of slow moving goods flow down the large rivers in the US, and probably in other Nations.

At one time barge canals were profitable. Certainly that was true in the US for a time, and it may still be true in a few locations in Europe and Asia.

The merit of your idea is immunity from weather delays.

A line along the Mississippi River might carry goods down the central corridor of the United States, as just ** one ** example of a potential site for one (or more) of your shipping lines.

(th)

tahanson43206 · Today 06:26:41

This is another attempt to encourage development of the enclosed passage transport idea ....

In order for this apparently worthwhile idea to move from the drawing board to reality, there needs to be a market.

There are NO such systems in existence on Earth today, which tells me the benefits of the proposal are not yet recognized.

It falls to the inventor of a major new way of doing things to persuade the customers of the advantages of the proposed system.

In thinking about potential markets, it occurred to me that a variation on the theme might be interesting to some funders.

The essential element of the proposal, as I understand it, is slow movement of goods carried along by a flow of water.

This is also characteristic of the time honored and very practical idea of using flat bottomed boats to move goods on inland waterways, with emphasis on rivers because they have established a natural gravitational flow that humans can harness.

So! Here is my idea/question .... suppose an entrepreneur loaded a small barge with soil, and planted seeds that would grow on the journey South (or downriver) to the market in one or more large cities. The supply of fresh water would be consistent throughout the passage, and sunlight would be abundant although no more reliable than a fixed location plot would see.

At the destination, the crop would be ready for harvest.

This idea would increase traffic on the river(s) where it is implemented. Is there an opportunity? Would there be objections? (no doubt)

The barges would need to be carried back up the river after they have completed their journey, but they could be stacked densely on large traditional barges.

The distinct advantage is that no infrastructure has to be added to implement the floating farm procedure.

(th)

Calliban · Today 07:02:04

A floating farm? I suppose it would depend on what you are growing and what advantage there is to growing it in a barge rather than along the river bank. Usually, the barge would ship the finished product. One problem with growing stuff in the barge itself is that food crops generally require a lot of space. It takes hundreds of square metres to feed one person on a meagre diet. In some cases, customers want living plants to ensure freshness. Corriander and basil are often sold as live plants. This is a case where your proposal could have merit, as the plants would continue growing as they were transported.

Rivers are an under-used resource in the US. If goods are carried in the direction of flow of the river, then the energy needed for transportation is effectively free. The goods just go with the flow.

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#126 2024-09-19 10:11:35

Re: Calliban Postings including links to notable contributions

#127 2024-09-19 11:30:08

Re: Calliban Postings including links to notable contributions

#128 2024-09-19 13:37:54

Re: Calliban Postings including links to notable contributions

#129 2024-09-19 14:29:18

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