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Ken Fabian

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Everything posted by Ken Fabian

  1. Which makes me wonder what we are arguing about - since that is what I have repeatedly been saying. I think this is incorrect - convection requires a difference in density (and gravity... or an acceleration like a centrifuge provides); different density due to temperature difference is just the most common, but having a different mix of gases with a different density will do it. Hydrogen, being lower density, will make convection. My citing the velocity of hydrogen molecules at 0 C was what I found and was intended as illustrative of the high velocity of gas molecules, far exceeding what gravity will do. I should add that doesn't mean I think hydrogen molecules will be bouncing off the walls and floor in a fraction of a second - they will run into other molecules along the way and how fast it disperses depends on (iirc) mean free path. Read my posts and you will find I spoke of other mechanisms all along. It looks more like you being hung up on diffusion, as if it were inconsequential. It isn't. I don't see how that reveals anything different than what I have been saying. Sure, the hydrogen in the bucket will be displaced faster by bulk gas movement (convection) than it could by diffusion. Not sure I am reading it correctly but a table of properties of Hydrogen (here) has convection (bouyant velocity) at 1.2 - 9 m/s - a lot faster than diffusion velocity of under 2 cm/s, but 2 cm/s is still significant in this hypothetical - the convection won't persist for long but diffusion will - from ceiling to floor of a 3m high space in a few minutes. Which won't be to homogeneity - I am assuming for the first molecules arriving? Sethoflagos or someone else likely knows better than me. Most of it will settle temporarily at the top but diffusion will happen from the moment the lid is removed. Do it in zero gravity without convection and the hydrogen will disperse faster than plain air - because hydrogen molecules move faster and that makes them disperse faster. The specific air molecules of plain air will disperse (and be exchanged by Brownian Motion), without changing concentrations.
  2. Hypothetically, yes; the coolant temperature is often higher than boiling point of water - from added glycol - but without running the engine at lower than ideal temperatures (with reduced efficiency) it won't produce a lot of steam. The waste heat from the vehicle's cooling system could also power a Stirling or an Organic Rankin Cycle engine. In practice these options would be a bulky and heavy additional load for a vehicle to carry and are not practical. Likewise storing the heat as hot water in dedicated tanks and offloading it for use - say home heating - would be impractical. I have some small hope that we will see significant improvements in thermo-electric technologies, including potentially optical rectennas aka nantennas that can turn heat directly into electricity, with some quite profound implications, including the ability to harvest energy from the night sky or sun warmed ground as well as direct solar or utilise waste heat or enable large scale thermal storage. Maybe not ever going to be practical but given the potential it looks as worthwhile as spending big on fusion energy - but I would be surprised if they get as much as 1% of the funding that fusion gets.
  3. Constancy of supply would be the main reason why, including beaming from power satellites in sunlight down to places where it is dark. I suppose they'll have short periods of being in Earth's shadow so no single space solar farm will be enough.
  4. It has been looked at before but technology does advance so another like would be good. I'll be very surprised if this can be a cost effective energy option, let alone something that can help us decarbonise energy production but investigating the possibility seems appropriate for a space agency. However I wouldn't want to see our legitimate goal of clean energy hijacked to advance entirely different goals; the confidence in the clean energy outcomes need to be there, before the massive investments and not buy into the "bootstrap" hype - going there first and then figuring it out just isn't good enough. As I usually do when space based solar gets attention, I wonder whether the energy transmission elements could be used without the solar collectors, to beam power up from one place on Earth and down at another, possibly with an intermediate transceiver to take it to the other side of the world. My understanding is that beaming power loses a lot of power, so maybe not but the less stuff we have to put into space the less it will cost; costs of launching payloads have come down a lot but it is still extremely expensive. Did I read somewhere else that they were considering directly powering things like aircraft with power beamed from space? If so that seems even more unlikely to be feasible - no diffuse beam could do that.
  5. Initially most of the hydrogen would rise due to convection and accumulate in a partially mixed state at the top of an enclosed space - partially mixed because of turbulent mixing as it rises and to a lesser extent from diffusion as it goes. The diffusion would be happening from the moment you lift the lid and it will be in all directions, including sideways and down and around. I would expect the convection to effectively stop when it settles in the top of the closed space and so long at there are no temperature differences, will subsequently be dispersing primarily due to diffusion downwards - because diffusion in other directions will be blocked by ceiling and walls. Give it time and it will mix all the way through by diffusion - with the caveat that there is a very small difference due to gravity, just not enough to be significant, just as dispersal is time dependent and arguably approaches but doesn't ever quite reach absolute homogeneity. Also there are going to be differences in dispersal rate due to the bucket making less room going down from above - effusion? Note that I'm basing this on my admittedly quite basic understandings. I can quote a diffusion coefficient of 0.61×10-4 m2 .s -1 for hydrogen gas (it has no term in it for gravity or direction) but struggle to do the calculations for how fast the accumulation at the top would take to diffuse through the whole volume. The reason I see for gravity to be effectively insignificant is that Hydrogen molecules move at around 2,000m/s at zero C and what gravity adds or subtracts is going to be relatively small. CO2 will diffuse lot slower because it is a heavier molecule - I haven't looked in the right places to a number to it - but it will still diffuse. That heat flows to where it is colder and does not flow to hotter is very like the way concentrations of one gas in a mixture will disperse to lower concentrations but not to higher. Without a source or extreme conditions it all goes one way, towards homogeneity.
  6. It does diffuse downwards. Diffusion works in every direction. It is a case of lag time in mixing, with sources adding it faster than it mixes, not stratification. Any lighter gases accumulating in a roof space, (like CO2 does in low places), are not yet well mixed when they rise (or sink). They may not appear to be concentrated "streams" but there will be enough gas seepage - faster than diffusion can disperse it - to make volumes of lower density air, that flow and rise. Enough in otherwise still air for convection to carry it.
  7. I think this is wrong - or rather, there is no perfectly still air (at greater than absolute zero temperature) because of Brownian Motion at the molecule level. Which is what drives Diffusion. Without a barrier the total volume will end up homogenous -
  8. @studiot my point was to clarify for readers that CO2 in mixed air doesn't separate and sink, even under those circumstances. We don't get stratification of the mixed air, we see stratification of pockets/volumes with different CO2 concentrations that have not mixed - yet. Sources will keep it that way but without them the enclosed air will - eventually - homogenize. Or I should say no significant stratification under ordinary Earth gravity; run it through powerful centrifuges and it can become significant. It is a common misunderstanding (whilst not claiming it of you) that CO2, being more dense, will sink to the bottom - and that the higher atmospheric CO2 concentrations nearer ground level are a result of the CO2 separating rather than the sources of CO2 being at ground level and there being a lag time in mixing. At small scale it mixes by diffusion. At larger scales by bulk air movements, ie wind and turbulence. For example thunderstorms will carry air from ground level to the stratosphere in one go, mixing vigorously as it goes.
  9. 2) - I think CO2 concentrations in confined spaces only stay high if there is a source, ie it starts with high concentrations and air mixing is impeded, by lack of air movement. A A fully enclosed space filled with air will still end up well mixed due to diffusion, not separated. A deep shaft with high CO2 that is open at the top will gradually lose CO2 until it has similar concentrations to the open air. No, not lying. Stop trying to sell the notion that climate scientists must be incompetent or biased, ie wrong; climate science is not about "selling" anything other than the best possible understanding of how our climate system works and responds to change, both natural and human caused. That isn't complete understanding but more than enough to know that the global warming problem is real, very serious and won't be self limiting over the timescales that matter to human civilisation and to remnant natural ecosystems.
  10. Thanks iNow - that answer does address the question. I do admit to some lingering doubts about how these economic benefits are calculated - I suspect a rosy glasses/PR team point of view - but accept that it is delivering them. Comparisons to the economic value of funding other things instead will always be difficult and speculative but still is valid to ask.
  11. To be honest I'm a bit disappointed with most of the comments. A bit too much falling back on the old truisms about serendipitous spin offs IMO rather than providing examples of how LHC has been delivering them - because not all research projects do deliver them. thewowsignal might not be contributing much to the discussion but it is a good question. Sure, the LHC's budget is small by the standards of the global economy but that is a disingenuous argument; it isn't a pot of money just waiting for uses to be put to, most of it - more than exists it seems, via borrowing and money creation - is spoken for and still leaves them short. There is no shortage of alternative uses where tangible benefits would ensue, that aren't getting enough. There are tradeoffs. Even the old "space programs delivered so much" thing - where truly massive amounts of government funding delivered some tangible technological advances with economic benefits - dodges the question of whether equivalent funding of other kinds of R&D would have done as much or more. These aren't arguments that much impress me. As science research project budgets go "high end" things like the LHC are very high cost and it is a legitimate question whether they are good value - because there are no shortages of underfunded research projects, with that same innate potential for serendipitous spin offs. Yes, pure research has delivered spin offs with useful applications and I am generally supportive of most kinds of R&D - and I'm pleased that some nations that can afford it do so. I think a complete understanding of the building blocks of matter, even without spin-offs does represent something intrinsically valuable - but not unquestioning support when it comes to how to get there. It isn't entirely clear to me that it is best achieved by this research project rather than a different one.
  12. Sounds like reasonable questions even if a regular internet search should provide an answer to how much it costs. But it is clear - even without knowing the specific numbers - that by most science lab standards it costs a LOT of money. I'm in favour of supporting research for the sake of understanding the building blocks of matter but it isn't clear how it has practical implications and of course there are trade offs; funding isn't infinite and bigger budgets for the LHC can mean reduced budgets for other things. Is it good value for money? I have no idea and with pure research we aren't necessary chasing specific applications, rather we aim for a better understanding of how things really work and hope for applications to emerge. Better understanding of what goes on with fusion and of what is required for fusion energy applications? Better medical or other diagnostic imaging? "Better" thermonuclear weapons? It would be interesting to hear what real world impacts people here think it might have.
  13. So much being said about Elon Musk right now but surely it is as simple as him being a bog standard anti-tax, anti-regulation, anti-union free market Libertarian who's commercial successes give him an inflated idea of his own insights in other areas. His Longtermist human destiny to leave Earth behind thing is a bit idiosyncratic but the temptation to try and remake the greater nation, economy, society more to his liking is not so unusual - just most people don't have the money or influence for it. More to his liking will almost certainly pare down to the same old unexceptional "what is good for my business is good for the nation" that other wealthy industrialists espouse. Which puts him firmly in the US Republican camp irrespective of how welcome the successes of EV's and batteries are to those concerned with the climate problem - who, by the failure of those on the Right to treat it seriously, are more likely to lean Left. The significance of social democratic policies (even the US has them, even if explicitly not referred to as such) to the opportunities for long term capitalist wealth creation won't get any credit. Like other rich and successful entrepreneurs his dealing with politicians and political parties will, unlike ordinary citizens, come with high levels of personal access and is likely to be a lot less ideological than it is transactional, especially given one of his major businesses depends on bidding for taxpayer funded contracts... but not his taxes.
  14. The value to fisheries may be there but there is no existing arrangement (as far as I know) for financing of seagrass habitat maintenance by the fishing industry - and I expect attempts to do so would be opposed. Like a lot of the value derived from environmental "services", they have been treated as free. Taxpayers will foot the bill and the fishing industry will - like most businesses - fiercely resist paying more taxes.
  15. It won't be a major climate solution and can only be an adjunct to building an abundance of clean energy to displace fossil fuel burning - which remains our single most effective action, the one that is not optional. Saving the seagrass that exists - preventing it's loss, which would add to atmospheric CO2 - looks like the more significant thing and that appears to require that shift to zero emissions to prevent the ocean heating that could damage existing area and slow the sea level rise that could kill them. Farming seagasses might help but unless it has some other commercial value to sustain it the funding will be hard to come by and is likely to get better results elsewhere, such as supporting that essential growth of clean energy.
  16. I've had a long running deep distaste for "rhetorical" violence - which often goes direct to the "kill them" option because "hit the Speaker of The House with the Official Gavel because she is a (leading) Democrat" doesn't have the rhetorical impact of "Hang Mike Pence". Most people would assume it is just rhetorical... but most people aren't subjected to politically motivated violence. To anyone who has it probably sends chills down their spines, possibly with flashbacks. At the heart of much violence, from minor to all out war is a belief that "they deserve it".
  17. Because of global warming those deposits are better left where they are and our efforts at building new energy supply should be focused on low/zero emissions options. Fossil fuels are too polluting. @Sensei I tried an upvote but clicked on down due to clumsiness; removing it and changing to up either didn't work (but it said it removed it) or someone else (x2) downvoted your comment, just in those few seconds. (Just tried again - the little x was there, like it was still mine - it did remove this time. I won't try the upvote again, but take it as given - Ken) I do think we are at or have crossed a significant tipping point on clean energy, even if it takes time to flow through sufficiently to influence those with Doubt, Deny, Delay as their climate policy. The fossil fuel supporters are doing all they can to encourage the view that we have a green energy crisis rather than a fossil fuel energy crisis - and use the sense of crisis plus the abundance of money from profiteering to encourage emissions reductions efforts be set aside. I don't think that will work. Going by Australia, that had more than a decade of pro-fossil fuels national government, the electricity industry has already shifted to supporting renewables. The only not-renewables new energy investment now current in Australia is a single gas plant, by government decree - by the previous Australian government.
  18. @awakening As the saying goes, extraordinary claims require extraordinary evidence - and getting energy from nothing counts as an extraordinary claim and you aren't providing any evidence. It may appear to you like people are closed minded and refuse to listen but people who have convinced themselves they have a perpetual motion/free energy solution - and remain closed minded and refuse to listen to people who point out why it won't work - are surprisingly common. Working examples are not. Conservation of energy isn't an arbitrary rule for excluding amateur scientists, it comes from a good understanding of physics, supported by observation and experiment. It doesn't take examining and understanding your proposed method to have very high, approaching absolute confidence that it won't work - sorry but Conservation of energy (more correctly conservation of mass/energy) has that level of confidence. Thus the requirement for extraordinary evidence, such as a working example in it's most basic form (no unnecessary or confusing embellishments) that can be independently examined and verified. For a verified working prototype one consequence would be a Nobel prize for whoever can explain where the energy is coming from. If it came from world leading Physics labs it would be astounding - and probably still be widely disputed. From an amateur it is just unlikely to be correct.
  19. @Philandes Just build lots of clean energy and let the coal plants close; there is nothing so good about coal power plants that we should go out of our way to preserve their viability. Quite the opposite - like so much is wrong about them that we should be going out of our way to get rid of them. We have more options now. The scale of greenhouse construction required would be staggering and coal plant operators are mostly struggling to remain economically viable and taxpayers are not going to support it... This taxpayer sure won't. I think your idea won't work - The exhaust gases won't make fertile soils - more likely they would contaminate soils or require treatment first, to be benign, without any specific benefits. Greenhouse plants can't take enough CO2 out of air to be effective as Carbon Capture; plants can't take out that much. The CO2 that greenhouse plants take in becomes CO2 again through decomposition; it doesn't remove CO2 from the carbon cycle. There is just too much CO2 - we now make more CO2 than all other waste combined, several times over. There isn't anything we make more of besides things like sand and gravel that we don't actually make. Stopping doing the things that make CO2 waste - making energy by other means - is always going to be a better option. @TheVat Agree 100%. The gas and oil industry is offering to do CCS for us IF taxpayer funding is provided to them to do it - so kind of them - but not at levels that would make a difference (apart from sounding 'green') and NEVER out of their revenues, not even revenues at the hyper profit levels currently enjoyed. They like Carbon Capture when they can pump the CO2 down oil wells to force more oil out of nearby wells - the single biggest use. They like it when they can take CO2 out of low quality natural gas they otherwise could not use, to make it more saleable (eg Australia's Gorgon Gas project, the single largest CCS project). They like it best when they get taxpayer funding to do it - and must think it hilarious (in private) when they get emissions reduction funding for activities that increase overall production of fossil fuels, that they know can't ever work at large scale to eliminate emissions. But I am not laughing. For CCS to be able to allow unrestricted use of fossil fuels without emissions it has to become the single largest industry in the world - but without any intrinsic way to be profitable. The largest industry ever, because we make more CO2 than anything else barring things like gravel that we don't actually make; for each ton of fuel burned there is 2 to 3 tons of CO2 - and it should be more than that, but for incomplete, inefficient burning. Any capture methods that combine CO2 with other materials, including plants, has to be that much larger again.
  20. If you are confident you know what it is you don't know then skip to the parts you feel you need, but if you aren't sure, go through them all in order and see. It shouldn't take long to find out whether each element is understood, then jump ahead, without doing all the exercises. Or not. My own experience is that missing something along the way can make what you are trying to learn a lot more difficult - the curriculam tends to designed to provide foundations that can be built on. I tried something similar, more to see if I could recover what I'd learned and lost than learn from zero - I can't say it went well and I suspect some of the parts I struggled with went all the way back to missed lessons at school, far too long ago. In my late 60's I don't take it in as readily as back then. Or retain it so easily... better than average recall got me through school, but now I struggle to remember where my glasses are... when they are hanging on a cord around my neck.
  21. Going by my own experience capillary action appears able to maintain high moisture levels in standing trees (Eucalypts mostly around here, in Eastern Australia) for many years after they died. Sawing standing dead trees into firewood still seems to require some additional time stacked to dry fully. Preferably they have been dead long enough that bark and sapwood are rotted/eaten away, but before the termites make much impact on the heartwood. That the wood hasn't been lying on the ground means less dirt and grit and makes it easier on the chainsaw, but I tend to use what is around and accept shorter intervals between sharpening. It also seems like simply drying green wood doesn't produce the best firewood and guides for Australian landholders providing their own often recommend a period of a few years of 'green' wood being kept deliberately damp, allowing bark and sapwood to rot away and saps to leach away before drying. Not using sapwood and leaching out of saps can be important because they can cause dangerous build up in chimneys/flues, especially with open fireplaces. It seems to be less important with modern enclosed wood heaters, that achieve higher temperatures and burning efficiency, ie can tolerate wood cut green and fast dried with sapwood still present. Some of the longest lasting, most termite resistant Eucalyptus timber seems to season best when left standing - least splitting or checking - with the downside of being hardest to saw when seasoned. More usually, commercially, the wood is milled green and stacked to air dry or else kiln dried. We still use some firewood but increasingly we use reverse cycle air-con (air source heat pump) for heating.
  22. There are big uncertainties and the IPCC reports do include mention of them. The sea level rise from thermal expansion is linear with respect to ocean temperatures and those do follow air temperatures but ice sheet melt (Greenland and Antarctica mostly) has high potential for non-linear contributions. The (average) rate of rise is currently a lot less than 6" per decade but it is accelerating. Places like the US Gulf of Mexico coast is running about twice the global average. Counter-intuitively the sea levels are falling closest to where land based ice has been lost, mostly Greenland so far, due to lowered local gravity from the loss of mass. This NASA video showing sea level changes (based on satellite data) shows this effect -
  23. The link also said - Sound like about the time the plants had ceased to rely on the nutrients that came in their cotyledons they had problems. Stunted roots is an especially bad sign. Likely that some nutrients are present but some important ones are either not present or insufficient.
  24. It takes active propulsion and navigation for such a thing to stay where it is put; sunlight pushes on things, the larger the exposed area the more it pushes. The lower the mass ie thinner, the more vulnerable. Probably to being eroded too. Lagrange "points" aren't truly stable either. Fun to speculate but I'm not convinced there is any need or even any benefit. It certainly isn't commercially viable to do much of anything suggested in this thread - most of which requires tech that doesn't exist and extraordinary financing - and there isn't a compelling case for colonising and terraforming for any "greater good", as a taxpayer funded program. Going back to the original post - I don't see how complex robotic machinery could be made without a whole lot more materials, equipment, industrial processes than suggested, without a whole advanced industrial economy's worth. Some of important materials are not economically viable to produce without a large economy making sufficient demand, let alone make them from moon rock, which has not undergone the geothermal, hydrothermal processes that separate and concentrate them into ores. Nuclear powered robots making nuclear power plants for robots? Is there even any concentrated ore for thorium? Evidence of thorium is of trace amounts scattered about, probably leftover from meteorite impacts. It may be fun speculation but that is all.
  25. The ability to utilise Infrared would be a big step forward - and not primarily for achieving higher conversion efficiency in sunlight but by making it possible to use low grade heat, including back radiation from nighttime sky or heat from the ground, or waste heat. It would open up the potential for 24/7 energy from a wide variety of sources, either to avoid storage requirements or by opening new possibilities for thermal energy storage. Besides thermo-electric generators there are Optical Rectennas that might manage this as well some other possibilities arising out of graphene research - but none are standing out as viable. Yet.
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