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# Ice Power

Creating electricity from cold weather
 (+4, -3) [vote for, against]

I heard a news item on the radio about how much it costs to grit roads in preparation for icy weather. The local authorities never know exactly which roads will become icy, and so have to over-grit. Along comes some rain and washes the grit away, and the itsy-bitsy grit lorry has to grit the roads again.

So I got to thinking. What if the local authorities got an early warning from a particular road that it was beginning to freeze? They could be reactive instead of proactive, and save lots of money (and grit!) But this would require thermometers installed at intervals along each road, with a signalling device and a power supply.

Unless... Imagine an airtight box, mostly filled with individual sacks of water (some kind of elastic material holding the water) and containing some air between the sacks. Place several of these boxes at regular intervals along the roads. When the temperature of the box falls to zero Celcius (32 F), the water turns to ice and expands, stretching the elastic sacks, taking up more space in the box and expelling the remaining air through a hole at the top. This air turns a turbine connected to a dynamo, creating just enough electricity to send a radio signal back to base to let them know that this area of road is beginning to freeze. Out go the gritters. No accidents this winter.

In the spring, the ice thaws, the sacks contract and the box draws air back in, getting itself ready for next winter.

If the energy created was sufficient, it could be used to heat an element embedded in the road, thereby preventing the road from becoming icy before the gritters get there.

I have no idea of how to calculate how much energy would be created - let the boffins do that. Of course, it needn't be air and water if better liquids and gases could be used. Air and water happen to be very cheap, though.

 — kevincherubini, Apr 28 2004

Refrigerants http://ctan.unsw.ed...refprop/HCprop.html
Looks like R-600 or R-601b would be good choices, though I have no idea about the environmental concerns with a large amount of the stuff around. [Worldgineer, Oct 04 2004, last modified Oct 21 2004]

 There are a few issues here. The main one is that the amount of energy you will generate will be little to none. First of all frozen water isn't much less dense than liquid water, which means you'll have to have a huge amount of it to generate a little pressure. Second, air's density increases as it gets colder, counteracting the freezing water's pressure increase.

It seems more useful to use a temperature gun to measure the surface temperature in front of a grit truck, allowing control of the amount of grit that should be dispersed.
 — Worldgineer, Apr 28 2004

 CFViiil. WAESklcome rtopi thjer ghjalkfbnaeruy.



Cool. Welcome to the Halfbakery, Kev Cherub. It might need a little work, but this idea I like. And I don't have to put on a squeaky voice to say so.
 — lostdog, Apr 28 2004

The basic idea of roads telling services when they need serviced is a good one, though, worlds. The "warming roads" thing I'm more than a little dubious about. But a valiant effort. Kev - "let the boffins do that" could be construed as meaning that you don't know what you're talking about. Quit while you're ahead, and try not to invoke technology that requires other people to fill in the blanks.
 — lostdog, Apr 28 2004

 Worldgineer: So what about using other liquids and gases, to produce more pressure, as I stated in the original idea?

 Don't much like the idea of a temperature gun mounted on the grit lorry. What if the temperature falls after the gritter has made his run?

lostdog: Thanks! It's nice here. Good mix of crazy ideas, interesting ideas, humour and banter. Too many categories, though! Naturally, I want to have an idea in each one, so it's going to take me some time.
 — kevincherubini, Apr 28 2004

Not many liquids expand when they freeze. It's possible to just use some sort of refrigerant with a boiling temperature of around zero (don't know of one off the top of my head) and use a turbine with air that is being sucked in to a chamber, but you'll still need a lot of it and you won't be generating much power - definately not enough to heat the roads, but I could imagine generating enough to operate a cell phone for a few seconds.
 — Worldgineer, Apr 28 2004

Yeah, if the assumption is that the intelligence is at the road, why not just install solar panels, batteries, thermometers and radios every so often along the road. The batteries can charge all year. The thermometers can measure the road temperature every 15 minutes or so - either year round or only during the winter months.
 — phoenix, Apr 28 2004

 Good point, phoenix. But solar panels, batteries and thermometers cost a lot of money. Bags of water in a box don't.

If money were no object, why not have a little man in a hut with a TV, kettle, supply of Pot Noodles and a few bags of grit out back? Whenever he feels the chill getting to his bones, he puts the kettle on, scatters some grit across the road and is back in the hut in time to eat his curry noodles and watch repeats of "Minder".
 — kevincherubini, Apr 28 2004

Solar panels, batteries and thermometers are cheap compared to installing any of this (plus you left out the cost of turbines, etc. in your "bags of water in a box").
 — Worldgineer, Apr 28 2004

I'm surprised this doesn't use piezoelectrics.
 — jutta, Apr 28 2004

Piezoelectrics - something to do with shoes?
 — kevincherubini, Apr 28 2004

Around here, yes.
 — DrCurry, Apr 28 2004

 What's a boffin?

 "solar panels, batteries and thermometers cost a lot of money. Bags of water in a box don't." I'd bet that a turbine sensitive enough to generate usable electricity in the proposed scheme wouldn't be cheap either.

 This would also be a one shot deal, right? If you could get the thing to generate electricity, it would only do so upon the initial freezing?

 Still, there should be some way to make this work. Any way to leverage the temperature differential between the road bed and a much deeper depth which remains at fairly constant temperature?

An array of low temperature thermocouples (magic?) that stop producing electricity at freezing and causing a transmitter to stop sending an OK signal?
 — half, Apr 28 2004

I like the method they use in Baltimore better. They simply fail to prepare for impending weather (plows, salt trucks and the like), and when snow comes they simply fail to adjust their driving habits. Whee! Repeat for decades as if nothing was wrong with this scenario. Oh, and buy toilet paper as if preparing for nuclear war.

Salt is damaging to your undercarriage anyway. If you're going through the expense, why not embed an electric heating grid in the asphalt? People 'round here do that in their driveways.
 — justaguy, Apr 28 2004

I've heard of nitinol switches being used to accomplish something similar to this.
 — waugsqueke, Apr 29 2004

 half wrote: "This would also be a one shot deal, right? If you could get the thing to generate electricity, it would only do so upon the initial freezing?"

 Not really, half. When the liquid thaws, it becomes dense again and takes up less space, creating a vacuum in the box and thereby drawing the gas back in.

Boffin: "A research scientist, often employed in armed forces or government work"
 — kevincherubini, Apr 29 2004

 I can't understand why this idea is getting so many fishbones!

 Let's break it down to its two constituent parts:

 1. Can we generate electricity from cold weather?

 2. Can we create a low-cost, low-maintenance early warning system to indicate freezing temperatures?

 1. Possibly, if I understand correctly what you boffins are saying. I read that whole article about refrigerants, Worlds, but I am none the wiser. The "bags of water in a box" idea seems to me to be just another form of solar panels and batteries. The solar energy is "stored" in the liquid water and released when the water freezes (i.e. returns to a low energy state). Needs some work, certainly, on the relative density of ice to water, the amount of pressure generated and the sensitivity/cost of the turbine. But in principle, would it work?

 2. If the solar panel, battery, thermometer and radio transmitter combination is cost effective (compared to the cost of rescue crews cutting smashed bodies from pile-ups) then go for it. What about areas that get very little sunlight, though? Roads in long tunnels, roads obstructed by walls and buildings or anywhere in Ireland? I believe the original concept of, as phoenix put it, having the intelligence at the road, is sound, though. It has to be better than road deaths and over-gritting.

So, two ideas that are sound in principle but require some development/research (by boffins). Worthy of a small croissant, at least?
 — kevincherubini, Apr 29 2004

Yeah, you have a point. We're all wrong, I guess. Maybe you should take this to another site where people are smarter, like you.
 — waugsqueke, Apr 29 2004

 waugsqueke wrote: "Yeah, you have a point. We're all wrong, I guess. Maybe you should take this to another site where people are smarter, like you."

 Where did that come from? When did I say that you are all wrong? When did I suggest that I am smarter than anyone? If anything, I admitted, twice, that I am not as smart of most of you who post in the "science" sections. Boffins is what I called you. To most people, that is a compliment. Maybe the word does not translate well to ... wherever you are from. But in the UK and Ireland, it is a term of respect, up there with savant and genius.

 I may have disagreed with some of the annotations to the idea. Isn't that the whole point of a debate?

And who are you to suggest that I go to another site? Is there something in that Help file that says I can't defend my idea with logical arguments? Or maybe your comment was meant to be tongue-in-cheek, in which case I misunderstood you.
 — kevincherubini, Apr 29 2004

Congratulations! you have encountered waugsqueke.
 — skinflaps, Apr 29 2004

 waugsqueke wrote: "If you have to tell people your idea is good, it's not."

Granted, that was a long time ago, but he still wrote it.
 — phoenix, Apr 29 2004

 "In the spring, the ice thaws..." does, for all practical road de-icing purposes, seem to make this a one shot deal. But, take it with a grain of salt, I live in the desert.

A once per season warning probably doesn't offer much value beyond a thermometer and observation of which roads have iced first in previous years.
 — half, Apr 29 2004

Why have the step of creating electricity? How about just have the box contain the grit too and when the box busts, it deposits grit on the frozen area.
 — dan1123, Oct 27 2005

New Hampshire is experimenting with a system that has sensors embedded in the pavement. When the pavement temperature goes down to a temperature slightly above freezing, the system sends a signal to a central location so that the sanders ("gritters") can be sent out. It is solar powered and also provides wind and weather information. I think it also has a camera, but I'm not too sure.
 — BMCCUE, Feb 21 2006

 couldnt you just fill a test tube sized container with water and cap it off so it cant evaporate then above the stopper have a button that when pressed sends a radio signal (assuming remote location so you wouldnt run wires).

 when the water freezes it pushes the stopper up which would hit the button.

could power the whole contraption with a small battery.
 — Xango, May 26 2006

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