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ScienceNostalgia101

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Posts posted by ScienceNostalgia101


  1. 2 hours ago, Strange said:

    I would be rather concerned that dumping all that in the lake would destabilise it and cause the very problem you are trying to solve.

    Also, what is the rate of CO2 production? Presumably this would need to be an ongoing process, not just a one-off fix.

    Yeah, I was thinking add it gradually, and find some way to store the CO2 (and/or use the forces resulting from a pressure change as an energy source if possible) while generating it.

     

    Also, if it releases heat energy, you could force the steam through a turbine and generate power while you're at it.


  2. They said there are 256 cubic km of CO2... that'd be 256 trillion litres, or 11.4 trillion moles of CO2.

     

    CaO + CO2 -> CaCO3

     

    To neutralize that much CO2 you'd need 11.4 trillion moles of CaO. Its molar mass is 56g/mol, so we're talking 640 trillion grams.

     

    That's 640 billion kilograms, or 640 million metric tons.

     

    This source says worldwide production of CaO is at hundreds of millions of metric tons per year. It's only a few years' worth of the stuff. You could put it on a boat (or a fleet of 'em) and let the currents take it to the east coast of Africa, then some trucks can take it the rest of the way. You mean to say people won't crowdfund to save lives?

     

    Methane might still be released, but it could be ignited.


  3. On 8/16/2018 at 11:26 PM, Endy0816 said:

    Weirdly was what happened in Toronto not a one-off event.

    https://www.nytimes.com/2011/08/15/nyregion/two-saved-from-drowning-in-stuck-elevator-on-si.html

    Solution: Don't have a basement.

    Joking aside people are going to need to rethink construction. Crazy how much damage even low cat hurricanes do when they end up hitting the Northeast.

    Huh. Both happened in major cities too.

     

    Rather than "don't have a basement," though, why not just have the elevators not go to the basement and for it to be a maintenance area accessible to maintenance personnel only?


  4. On 8/15/2018 at 2:00 AM, druS said:

    Building rules on lifts (elevators) differ around the world, I speak from experience in Australia and the UK - not USA.

    Cell/Mobile reception

    Lift cars can and are sometimes made of glass. The core that lifts sit inside are mostly made of structural concrete, though sometimes lightweight infill cores are used. Generally it is a matter for efficiency of structural engineering and you would lose an aweful lot of space to sit the lift outside of the shaft. This is sometimes done in lobbies etc where a steel structure is used with glass, and a glass lift car. You can then see through.

    But that does not necessarily give you mobile/cell reception. External glass curtain walls contribute most of the interference issue to mobile/cell reception in city towers. This is overcome by DAS (Digital Antennae System) systems - essentially a repeater system plugged into cable and distributed through the building. Most Premium grade buildings are briefed to maintain reception in lift cars (granted that from personal experience it is not easy to achieve 100%).

    But mobile/cell is not an emergency call out system. Lifts are required to have handsets which call back to a central point - generally the lift service provider. AND a stopped lift should be noted back in the control system anyway so that a call out should be alerted.

    "Airholes"/Lift Shaft ventilation

    This generally depends on the size of shaft and speed of the lift, but most lift shafts will have vents to reduce pressure build up as the cars move up and down. It isn't really for fresh air for human breathing - there should be enough air in a shaft that this is not a problem anyway.

    Lift "flood measures"

    The lift pit will generally have a sump which in normal circumstances should be dry. You would normally expect  a float system in that sump that is linked to the building control system. This is primarily for equipment protection, but should also set off alarms in this scenario.

    I note that far and away the most likely reason behind lift shaft flooding is a burst pipe or some similar internal issue. And this too should have already alerted on the building control systems.

    External flooding would be something you would expect the building management to step in on. Though if this is "flash" flooding possibly not quick enough. But someone should know what is going on and be calling in assistance. In flood prone areas, design would usually involve unseen barriers at street level to keep extrernal water out on the basements - up to a limit anyway. If there is catastrophic flash flooding you wont keep the water out. As others have said, it isn't common.

     

     

    In general existing building design and should be enough, if implemented reasonably.

    Thank you for the information! This is the best explanation yet!


  5. On 8/13/2018 at 10:54 AM, Sensei said:

    @Phi for All

    There is alternative design, vertical axis wind turbine.

    https://en.wikipedia.org/wiki/Vertical_axis_wind_turbine

    There should be made experimental offshore field of traditional wind turbines, mixed with vertical wind turbines, and performed experiment how well they will survive/behave in hurricanes/storms.

    If test will prove they are better in such unfriendly weather environment, they should be used instead of traditional design.

     

    You mean something like this?

     

    220px-BR_T01.jpg

     

    That's kind of what I had in mind when I said "horizontal instead of vertical." I didn't mean the axis was horizontal, I meant the blades, instead of going up and down, went from N to E to S to W... or in the other direction, depending upon how the hurricane approaches it.

     

    As for other wind turbines, even if they have to shut down for full-blown hurricanes, doesn't that still mean they can sap the energy of developing hurricanes? (Ie. Ones that haven't yet achieved hurricane force winds but might not at all if wind turbines sap their energy sooner?)


  6. On 8/9/2018 at 2:35 AM, Sensei said:

    Probability of being flooded inside of elevator is smaller than winning on lottery..

    Making airholes, just in case of hypothetical flooding, can save somebody from drowning, but can as well kill somebody else, when there is fire in the building (i.e. toxic gases).

    Hermetic elevator could kill somebody when there will be some kind of failure disallowing opening door etc. i.e. "stuck in elevator overnight"..

    Simply, it's not possible to predict the all possible cases, and make the all possible "just in case" features (and some of them are mutually exclusive).. Only the most probable cases are worth the effort.

     

    "Hermetic" elevator?

     

    What of the notion of making it out of glass, such that it can be, like other glass, broken in the case of an emergency? That way they could also see what's going on outside the elevator and whether it's better to stay or go.

     

    As for Frank's idea, what I was thinking was concave-up, not concave-down. (Ie. Inverted dome to collect the water.)


  7. Inspired by my own thread on forest fires.

     

    https://energyeducation.ca/encyclopedia/Betz_limit

     

    So basically, the Betz limit suggests that a theoretical maximum of 59.3% of energy could be extracted from wind at a time. That leaves 40.7% or more still in the wind.

     

    So, wind retains at least 0.407 times its maximum energy; which, by E=mvv/2, suggests it retains 0.638 of its speed. Does that mean that with a long enough row of closely-packed, highly-efficient wind turbines designed to handle hurricane-force winds, you could reduce the wind speeds from 120 km/h to about 77km/h, storing the excess energy until the power lines are repaired?

     

    Alternatively, what if one build a GIANT wind turbine... and/or made it horizontal instead of vertical. (Ie. Flat to the surface... or close-to-flat, given Earth's curvature.) If it were hundreds of kilometres wide, would any hurricane that passed through it turn horizontally aligned blades and convert the kinetic energy to storable electrical energy that way?


  8. Gah, forgot 2nd time around that I even specified saltwater 1st time around. The idea was that it'd be a waste of fresh water to use it or this and I'd like to use something otherwise useless. Even so, the idea is at the very least use something other than tapwater, to make use of the thermal energy.

     

    Not that I've let go of the saltwater idea completely... could a secondary container separate water whose salinity is increased by boiling from the less-salty water such that sea salt could be concentrated and stored? Do the materials this used in order to store molten salt hold a chance of being used on the inside surface of such a large container?

     

    Pond water or lake water, at least if it was from unused areas, might be preferable to saltwater, but what about sewer water? Would the methane vapours produced be ignited by the heat, further helping to boil the water?


  9. For the record, I since realized that in light of Toronto's size, a literal half-sphere is out of the question, but... what about an ellipsoid?

     

    1. Ah! That's actually pretty good!

     

    2. But sewers are a network of several pipes that each have to be very meticulously placed and fitted. This is just one giant ellipsoid. Cost of materials aside, how delicate an operation can constructing a concave-up ellipsoid be?

     

    3. Might be too late for that. Mind you, I'm all for taxing carbon to pay for whatever infrastructure improvements are needed, but I'm not counting on stopping it.


  10. That could go either way, though. With a woodstove, you don't need as big a container of water, but you need to select the wood and transport it to where it is being burned. With a forest fire, you'd need a HUGE container of water... but the fire comes to you.

     

    Cast iron's apparently $1.29 per kilogram... how thick would a cast iron container need to be to withstand flame while holding water? (I could probably derive a function between surface area and cost/revenue from that... I also realized now that perching something rectangular would also be wasteful, as it makes it difficult to relocate from the forest one just torched to a forested one, so whatever I come up with will be either cylindrical or spherical.)


  11. This year's California fires reminded me of this subject. California's a state that seems to be on fire especially often.

     

    I've since come up with another option. What about, instead of pipes, a large container, with a base and walls, (and maybe a roof) to boil the water? If they could make it thick enough to withstand the heat, would it be more practical to use the boiled water directly (cooking, coffee, etc.) or to put a hole in the roof to force the steam through it to turn a turbine?


  12. https://www.cp24.com/news/men-rescued-from-flooded-elevator-after-rain-storm-in-toronto-1.4044296

     

    Yesterday's Toronto floods got me wondering about better flood control measures and/or better ways things could be designed to be harmed less by a flood.

     

    1. It says people needed to be rescued from a flooded elevator. If they're not airtight enough to keep the water out anyway, why not put airholes in them so that people don't have to worry about suffocating from being stuck in the elevator? Why not make them out of glass so that there would be good enough cellphone reception to call for help, and if that doesn't work, to break the glass and escape?

     

    2. Why not build a giant half-sphere; concave-up; to collect rainwater such that it could be redirected away from the city and toward farms?


  13. So I was recently watching this video:

     

     

    1. Why molten salt in particular?

     

    2. How do they decide the size of the mirrors involved? On a related note, would it be significantly more expensive, less efficient, or both, to use one giant concave mirror than several flat ones? Or is there a risk a giant concave mirror would break?


  14. I keep hearing that epsom salts are good salts to electrolyze, because the sulfate ion is supposedly stable enough not to break down into sulfur or oxides thereof from the electricity.

     

    However, something like the carbonate ion, in the context of carbonic acid, breaks down spontaneously; carbonic acid breaks down into carbon dioxide and water vapour without any electrical current at all needing to be applied.

     

    Is there any table of known products of electrolysis, and/or handy rulebook for predicting them?


  15. I checked the bottom of it and it says "7 other." Which, looking it up, yields this. A tad concerning, but it says nothing about the vapour pressure from melting.

    Also, not sure if anyone here might recognize the numbers to the left of it, so I uploaded this image of it.

    As for gloves and safety goggles, I'll keep that in mind should I choose to go through with this.


  16. I have a bunch of spare plastic around that I'm considering melting into a plastic sculpture just to prove I can. Is there any way to melt plastic without burning it and/or causing significant amounts of toxic fumes? (By significant I mean enough to harm people either a few metres upwind or several metres downwind; or does that follow from the vapour pressure of molten plastic?)


  17. The idea was to build it prior to the forest fire, in anticipation of where they typically are. @ HallsofIvy

     

    The twin towers weren't filled with water, though. Wouldn't water flow to wherever the water level was dropping in the pipe? If not, why not, and if so, why wouldn't that constant contact between water and steel resist temperature increases beyond the boiling point of water? @ Area54

     

    I have no idea how much it costs to build an elevated pipe or a wider, more rectangular container of water, nor where to start on that one, so I was hoping someone more familiar with either could fill me in on this.


  18. Here's one out-of-curiosity question, similar to Raider's but without the "one way mirror" to consider.

     

    If someone made a closed container, coated on the inside with the most reflective material possible, and put a laser pointer inside it (set to go off at a given time) and used up all its light to completion, where would the light go?

     

    Would it all be absorbed/transmitted, even by whatever degree of either it has? And would reflectance give way to absorptance and transmittance once the intensity of light increased?


  19. I've seen a number of formulae in electromagnetism refer to the "number of turns in a wire;" not some function that converges at infinity, but rather linear proportionality. (To things like magnetic field, magnetic inductance, etc...)

     

    I get that, in practice, once a current carrying wire generates a magnetic field, this creates a back emf and decreases current to some equilibrium level. But in that initial instant; when the current begins to flow; does this mean you could have a theoretically infinite magnetic field/inductance/etc... with enough turns of wire?


  20. Year after year, somewhere in the world, its forests are on fire. There's a lot of talk about people displaced, but not about energy that went to waste.

     

    Is it at all possible to set up a network of pipes carrying seawater, (and/or giant enclosed containers of the stuff; obviously not tall, just long and wide) such that any burning forests underneath them would force the resulting water vapour into a pressure release valve underneath a steam turbine?

     

    Apart from any initial investment in such a project, would there be significant maintenance costs?


  21. Eh, it's fine, turned out my hometown went ahead with that municipal fireworks display after all. Forgot all about this thread after that until now.

     

    Another question, for future reference; would glass store the hydrogen more effectively? If so, and if I put a balloon full of air over the tip of the bottle, would it become 50% hydrogen by diffusion? (Or alternatively, more than that because hydrogen is lighter than air?)

     

    And even if so, would there be a way to get the concentration higher than 50%? Would a tube of water inserted underneath the balloon, filling the bottle, force hydrogen into an empty balloon wrapped over the tip?


  22. I've got a whole bunch of half-drained batteries and wood ash around, and I was considering making homemade hydrogen-based fireworks with electrolysis for Canada Day.

     

    1. I tried testing the wood ash for hydroxides by putting them in an aluminum can and mixing them with water, but it didn't dissolve the can. Are carbonate compounds effective enough electrolytes? Are they safe to use?

     

    2. Do balloons store hydrogen reliably for days? If so, does it depend on the material? If not, do you know of what else can be used to store them that can also be used to pump the hydrogen into balloons? Or if not balloons, do you know what else would be lightweight enough to float when filled with hydrogen? (I'm not talking on the scale of blimps here, I'm talking anything the size of balloons or only slightly bigger.)

     

    3. I was also wondering how to light them once they're in the air. Would throwing a sparkler do the trick, or would it be better to soak a thin string attached to the balloon in gasoline? Would the fire be out before the string hits the ground? (I could do this well away from any houses or trees, but ideally I'd want to avoid the hassle if it's safe enough.)

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