Half a croissant, on a plate, with a sign in front of it saying '50c'
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My Esteamed Colleagues

no sweat
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So we take an old dead hot water tank.
We cut away the outer shell and insulation and extra bits leaving us with just the inner tank itself.
We fill the bottom third or so of the tank with hydrophobic sand and wire an old ring-burner stove induction coil near the bottom.
We then add a water intake and pressure regulated outlet and wire it to a wind turbine. AC or DC, induction don't mind.

Sand can hold many hundreds of degrees more heat than water.
Water can not touch the induction plate meaning no deposition of lime or anything else to degrade efficiency.

It is a steam generator which will produce orders of magnitude more energy than it takes to heat.


Meanwhile, in Finland ... https://www.bbc.com...nside%20the%20sand.
[pertinax, Feb 06 2023]

wind powered heating and thermal storage https://solar.lowte...brake-windmill.html
[pocmloc, Feb 06 2023]

[link]






       Am I wrong?   

       Sorry, the laws of physics don't change unless you're a cat. How do you expect this to emit more energy than is received?
Voice, Feb 06 2023
  

       Well the ring burner induction coil will burn out pretty quick, due to the sand being non-conductive and therefore non-inductive, and due to the higher temperatures achieved. After that electricity consumption will rapidly fall to zero.   

       Meanwhile the sand keeps getting hotter and hotter (somehow) and this continues to produce a stream of super-heated water at over 100° C for as long as you need it.   

       Am I getting close?
pocmloc, Feb 06 2023
  

       It won't produce more energy than its input, but it could be an effective system for energy storage, to be released when the wind isn't driving the generator.
xenzag, Feb 06 2023
  

       //Am I wrong?//   

       Yes, but what [xenzag] said. See link.
pertinax, Feb 06 2023
  

       Clever Finns..... imagine the benefits if this was taken up and used by a large array of wind turbines such as the UK has. I love it.
xenzag, Feb 06 2023
  

       Clever Finns..... imagine the benefits if this was taken up and used by a large array of wind turbines such as the UK has. I love it.
xenzag, Feb 06 2023
  

       You can also use a windmill to generate heat directly, without an electrical stage inbetween the mechanical and thermal stages. You attach the drive shaft to some kind of paddles in a tub of water, and the stirring heats the water. If it is designed properly it will be more efficient because you skip the losses at the generation stage. I wonder if you could use paddles in sand instead of water to directly heat the sand.
pocmloc, Feb 06 2023
  

       //Well the ring burner induction coil will burn out pretty quick, due to the sand being non-conductive and therefore non-inductive//   

       For my prototype I'm using a cut off beer keg and a coffee pot element. I placed several induction plates in the sand with the burner. It shows no sign of burning out... yet.   

       hmmm, I figured that since I can get the sand up to several hundred degrees, and water steams at one hundred degrees, once it is at temp it could power a steam engine which should produce more electricity than it takes to run the induction heater.   

       A coffee pot doesn't take much power and steam can make a lot.
I believe you guys but I think I need to see for myself.
  

       // a steam generator which will produce orders of magnitude more energy than it takes to heat. //   

       // once it is at temp it could power a steam engine which should produce more electricity than it takes to run the induction heater. //   

       "BAD SCIENCE - the invention is intended as a serious suggestion, but is based on scientific 'facts that are widely known to be wrong. ... 'In this house, we obey the laws of thermodynamics!'"
a1, Feb 06 2023
  

       Well, when I finish my time machine I will go back and have serious discussions with my past guidance councillors.   

       //It is a steam generator which will produce orders of magnitude more energy than it takes to heat.//   

       Explain this.
  

       As read, it is an 'over unity' generator, which turn out not to work in the real world. Hence all the objections above.   

       Perhaps this is a typo, and you meant: store thermal energy in orders of magnitude less volume than water could, and/or get the energy out much more quickly than it went in.
Loris, Feb 06 2023
  

       // I will go back and have serious discussions with my past guidance councillors. //   

       The ones who tried to get you to pay more attention in class? Science or spelling?
a1, Feb 06 2023
  

       //Explain this.//   

       It was just a thought experiment.   

       What would happen if you used induction to melt a glop of molten steel into an insulated container of water with hydrophobic sand beneath the water and lock the lid?   

       Sure you'll lose some of the heat of the iron to the water but most of it will bury itself in the sand and the sand will absorb the heat.
There would be no containing the steam it would create and if the closed lid was really a massive piston then I should be able to use it to drag enough magnets through coils to produce more power than it will take to heat the next glop of molten steel with induction.
  

       I didn't realize I was trying to break universal laws here.
I just thought that the energy it takes to heat dry sand would produce more steam power than it takes to keep it hot.
  

       //The ones who tried to get you to pay more attention in class? Science or spelling?//   

       You know, there were so bloody many of them that it's really hard to say for sure.   

       ...oh yeah, the coffee pot heating element fried some time during the night, but the sand was still warm.   

       Back to the drawing board.   

       //when I finish my time machine I will go back and have serious discussions with my past guidance councillors//   

       Only to discover many many years later having necessarily taken said guidance councillors place after said //serious discussions// to avoid any undesired changes to the timeline (other than the one you wished to make) that you were that guidance councillor and it's all your own fault, Oh! and it also turns out you were also both your own mother *and* father by some curious twist of fate, which might explains a lot perhaps ;p
Skewed, Feb 06 2023
  

       I like over unity devices but I prefer ones that are harder to work out what the problem is.
pocmloc, Feb 06 2023
  

       //Clever Finns..... imagine the benefits if this was taken up and used by a large array of wind turbines such as the UK has. I love it///   

       Solutions like this work for Finland, because Finland has very small problems. Their population is 127 well educated responsible people in ludicrously well-insulated homes who are happy eating only herring and elk. They are surrounded by 1 squillion sq km of firewood that grows everywhere apart from the bits of country that are perfect for wind or hydroelectric electricity generation.   

       //I didn't realize I was trying to break universal laws here.//   

       Helps to have a few figures about the known universe to hand. Convert it to whatever makes the most sense to you. Same with concepts. Temperature and heat for example.   

       It helps to know that water is remarkable for example, it takes 4.2J (of thermal energy, heat) to raise 1g of water 1 degree (kelvin/C). Sand is much more conventional at 0.8 ish Joules to raise it's temperature 1 degree. So if we raise the temperature of 1l (also 1kg) of water by 50C and 1kg of sand by the same 50C, we have a big difference: Water (1000gx4.2x50C = 210,000J) vs Sand (1000gx0.8x50C = 40,000).   

       So sand is a sucky heat storage medium in terms of space efficiency, it also conducts badly (the Finns push air through it to get thermal transfer rates up to acceptable levels) and doesn't self-mix by convection, which might be an advantage. But, it's cheap, you can heat it to ludicrous temperatures without it turning into dangerous high temperature/pressure gasses like steam.   

       So how about the generation of steam? Well this is phase change. This gets really interesting. Changing 1kg of water from liquid to steam with NO TEMPERATURE change is 2200j/g. Which is nuts. Change that into anything you like, that's 2200W for one second for each gram, 2200W for 1000s (17 mins) for 1kg. Or in terms of sand. Say we have sand at 500C, and we want to boil 1kg water, how much do we need? 2200 x 1000 = 2.2 million, or 2.2 megajoules. Sand is 400C different at 0.8 = 320 J/g. 2.2million/320 = 6.85 kg sand at 500C to boil one kg of water. Assuming that water was already at boiling point.   

       That wouldn't work in practise for any useful purpose of course. You'd have to start pressurizing it, then you have to use energy to boil the water, and make pressure, which raises the boiling point, which needs more heat. There's a reason steam engines use tons of coal.   

       The advantage of sand of course, is that you can move away from low grade heat and have temperature differences big enough to work with efficiently.   

       Nothing wrong with using sand to store and buffer heat energy however. If all you want is heat, you have an easy life, you can just go generator>resistive heat element. The heaters won't care if its DC or AC or what wave form it is.
bs0u0155, Feb 07 2023
  

       Wow, okay, that hurt something in my head a bit, but I ken.   

       I want to use sand as storage for heat specifically because it holds a lot of heat, but not well.   

       I literally intend to dump as much waste heat into a massive sand battery beneath as large a solar updraft tower I am allowed to build...
...and soon.
This posting was just an offshoot of daydreaming about possibilities of using that 500 or so degree heat I'm going to store within the radiant tanks, which I intend to use to heat ever expanding parts of this 20 ft. deep sandpit we're sitting on which will angle-passively flow back to the updraft tower like upside down rivers, the rising heat columns of which I will get to walk around within.
  

       One day it will create its own suction and I will be able to channel heat downwards to join the eventual torrent of wind.   

       Sand has low thermal conductivity, so it hangs on to the heat you dump into it (which is what you want). 0.25W/mK compared to water at 0.6W/mK.
Might need to put an auger or something into your sand pit, to mix up the sand & distribute the heat through-out.
neutrinos_shadow, Feb 08 2023
  

       What do you think about air-flow fluidization from beneath to rapidly disperse heat once the sand battery has fully dried?   

       I haven't been able to think of a better way to both dry the sand and disperse the heat than that.   

       //air-flow fluidization// an excellent idea. It runs into a surprising problem that we share however. I want to build an extremely low flow (~5-20ml/min) water cooling system for a computer, hotter the water the more efficient the radiators, you need way less air flow, smaller fans, all the tubing is tiny, pump consumes v little power, great. But find a fan/pump that runs reliably for years over 85C. They exist, but the cost will make your eyes water. Fluidizing sand by pumping 500C air? You're into high end forge gear there. It's challenging because all the grease melts, or it's so thick it doesn't work at normal temps. Or all the tolerances are off. Etc. Expensive.
bs0u0155, Feb 08 2023
  

       I'm not expressing myself well. The air used in the fluidization of the sand, although perhaps preheated by, would not be created from the heat of the tanks but from compressors powered by the electricity generated and stored form that rising heat only when needed.   

       Need extra wind to meet demand? Just divert a portion of electrical production towards fluidizing the sand-battery for a minute or two and you've got all the thermally expansive wind you need.
Cut off the fluidization and it goes back to minimally radiant thermal storage once again.
  

       Does that make sense?   

       Nope.
a1, Feb 08 2023
  

       Twoey, the most basic law of the universe is that at best you get the same out of a system as you put in. And usually less.
  

       This is so fundamental that it has different terminology to show its relationship to different fields:
In Chemistry, this is known as Hess's Law.
In Physics, conservation of energy.
In Computer science, GIGO - "Garbage In, Garbage Out."
In the humanities, "There ain't no such thing as a free lunch."
  

       If it looks like you're getting more out than you put in, it's usually because 'the system' is bigger than you are considering. Life on Earth can keep going, with its various 'cycles', because it gets energy from the Sun, which is gradually using up its fuel.
Loris, Feb 08 2023
  
      
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