A Road that Clears Itself

[nissangirl74]

solar roads. How cool would this be? I hope they find a way to make this happen.

http://www.thecarconnection.com/marty-b ... and+Blogs)

[Urabus GodofTraction]

solar roads. How cool would this be? I hope they find a way to make this happen.

http://www.thecarconnection.com/marty-b ... and+Blogs)

It's currently 0* here. No way solar power could provide enough juice to melt the snow, without creating some sort of 32* icey disaster.

Commenter on the blog who said it would be cheaper just cover the highways is on to something...

[AZ89two4Tsx]

^ That's not the point.

The point is that the roads will generate excess electricity. The idea is no way profitable or "smart" right now, but that is because of the lack of efficiency the current solar panels have. It is a step in the right direction though. I imagine once solar panels become more efficient, these little roads will start popping up in sunny states like AZ. As far as melting the snow....eh......

I'm curious to see how they would be maintained.

[Urabus GodofTraction]

^ That's not the point.

The point is that the roads will generate excess electricity. The idea is no way profitable or "smart" right now, but that is because of the lack of efficiency the current solar panels have. It is a step in the right direction though. I imagine once solar panels become more efficient, these little roads will start popping up in sunny states like AZ. As far as melting the snow....eh......

I'm curious to see how they would be maintained.

Read the article, homles. The whole thing is written toward deicing.


I think some sort of piezoelectric device would prove superior. In high traffic areas, or course.

[AZ89two4Tsx]

Meh, I'm pretty sure their main goal is not to just de-ice the roads. There are far more superior ways to accomplish that than solar panels like you stated.

Besides, when it's snowing, isn't there clouds? And when there's clouds, is there much sun? Then you have to bring batteries into the equation if it's not hooked up to the grid. Sounds pretty inefficient.

And if there's a bunch of traffic, how's it getting any sun? If these are going to be usable, I think it would be on a road like this.

[Urabus GodofTraction]

Besides, when it's snowing, isn't there clouds? And when there's clouds, is there much sun? Then you have to bring batteries into the equation if it's not hooked up to the grid. Sounds pretty inefficient.

Ice be the problem. Take today; ~10*, tons of sun. Ice everywhere. Black ice too, the kind that sneaks up on you.

[nissangirl74]

I would think that in the areas where it snows it would absolutely be the main reason for using them. However, out here, the amount of electricity that could be generated would be phenomenal.

[Urabus GodofTraction]

I would think that in the areas where it snows it would absolutely be the main reason for using them. However, out here, the amount of electricity that could be generated would be phenomenal.

Average two-lane road? 24ft wide. A length a mile long, we're talking 126,720 square feet. Ice half an inch thick would come out to 63360 cubic feet of water. 7.48 gallons a cubic foot, 8470 gallons of ice a mile, basically. Ice at 0*C, Need to raise that 1*C. So 4.2 joules a gram. 3785g of water in a gallon, so 32058950 grams of ice on a mile of roadway, requiring 134,647,590 joules of power to warm it up 1*C. If I'm right, that's 37 kWh to raise the temp of a mile of roadway ice one degree.

A square meter of solar panels at the current level of tech produces about a kWh a day. The math just doesn't work. We'll break the speed of light before an economical way of deicing roadways via radiant heat is invented.

[nissangirl74]

I would think that in the areas where it snows it would absolutely be the main reason for using them. However, out here, the amount of electricity that could be generated would be phenomenal.

Average two-lane road? 24ft wide. A length a mile long, we're talking 126,720 square feet. Ice half an inch thick would come out to 63360 cubic feet of water. 7.48 gallons a cubic foot, 8470 gallons of ice a mile, basically. Ice at 0*C, Need to raise that 1*C. So 4.2 joules a gram. 3785g of water in a gallon, so 32058950 grams of ice on a mile of roadway, requiring 134,647,590 joules of power to warm it up 1*C. If I'm right, that's 37 kWh to raise the temp of a mile of roadway ice one degree.

A square meter of solar panels at the current level of tech produces about a kWh a day. The math just doesn't work. We'll break the speed of light before an economical way of deicing roadways via radiant heat is invented.

You're better at the math than I am, obviously, so work this for me. In theory, if the roadway is heated, the ice / snow would melt on contact, right? Would it take that much energy to keep the road clear or are you trying to melt from a dead cold start?

[nissangirl74]

We'll break the speed of light before an economical way of deicing roadways via radiant heat is invented.

How about geo-thermal?

[Urabus GodofTraction]

Average two-lane road? 24ft wide. A length a mile long, we're talking 126,720 square feet. Ice half an inch thick would come out to 63360 cubic feet of water. 7.48 gallons a cubic foot, 8470 gallons of ice a mile, basically. Ice at 0*C, Need to raise that 1*C. So 4.2 joules a gram. 3785g of water in a gallon, so 32058950 grams of ice on a mile of roadway, requiring 134,647,590 joules of power to warm it up 1*C. If I'm right, that's 37 kWh to raise the temp of a mile of roadway ice one degree.

A square meter of solar panels at the current level of tech produces about a kWh a day. The math just doesn't work. We'll break the speed of light before an economical way of deicing roadways via radiant heat is invented.

You're better at the math than I am, obviously, so work this for me. In theory, if the roadway is heated, the ice / snow would melt on contact, right? Would it take that much energy to keep the road clear or are you trying to melt from a dead cold start?

We're talking the energy required to raise water 1*C. I don't know the math behind water losing it's energy in, say, 10*F outside air, so I can't tell you the energy required to keep water heated.

My figure is the energy required to heat a mile of roadway covered in ice once. If snow falls on it, you're going to have to expend energy to heat that bit of water too. So no, that is not to keep a road clear OR melt from a dead cold start. It's just to raise the temp 1*C. To actually melt ice (and keep it melted) you're looking a much more.

Honestly we're right at the edge of my knowledge, I left out enthalpy of fusion and probably a hundred other variables. In fact, a little more digging says it's about .1 kWh to thaw a gallon of ice... what did we have, 8470 gallons? That's 847kWh... that can't be right, that's a huge sum...

Geothermal, as in a powersource? Well sure, or nuclear, or coal, or whatever. You could get your 847kWh anyway you want it.

Geothermal as is let's use magma-heated water to radiantly heat a road (similar to floors that use heated pipes)? Not really possible on any sort of scale.

[nissangirl74]

Regardless, at the moment it seems unfeasible. It would be sweet though if they could figure out a way to make it work. I like the idea of using it out here to generate power. It would lessen our dependence on our other natural resources which can be stretched to the limit at times.

[Urabus GodofTraction]

Regardless, at the moment it seems unfeasible. It would be sweet though if they could figure out a way to make it work. I like the idea of using it out here to generate power. It would lessen our dependence on our other natural resources which can be stretched to the limit at times.

Even if I'm wrong (have Redcoupe or somebody who took a thermo class to the real math), the point is staggering.

The amount of power generated could be staggering, too. Assuming an impossible 100% conversion of solar energy into electricity, you're looking at a mile of roadway creating 70,640kWh a day. Of course modern panels are only about 20% efficient, so...

[nissangirl74]

Regardless, at the moment it seems unfeasible. It would be sweet though if they could figure out a way to make it work. I like the idea of using it out here to generate power. It would lessen our dependence on our other natural resources which can be stretched to the limit at times.

Even if I'm wrong (have Redcoupe or somebody who took a thermo class to the real math), the point is staggering.

The amount of power generated could be staggering, too. Assuming an impossible 100% conversion of solar energy into electricity, you're looking at a mile of roadway creating 70,640kWh a day. Of course modern panels are only about 20% efficient, so...

....so it would take a long a** time to make the money back, either way. They will become cost efficient, when all other sources have been depleted.

[raremotive]

It would be more energy effective to melt the ice before it became ice than to try to melt it all at once. Since the heat would dissipate into the complete block of ice by conduction. But how much energy do you have to lose under convection to ensure no ice build-up?

Thermodynamics is just energy balance. You get out the same energy you put in.

[krash]

The process seemed straightforward enough: the company embedded LEDs in high-density glass pavement, as well as tiny solar elements to power them. The result?

No traction in the rain?

[Bubba1]

Heated driveways/sidewalks have been around for awhile, though not solar powered and not on a grand scale (like a roadway).

In affluent Hinsdale, IL, where homeowners have been tearing down modest old homes and replacing them with gawdy mcmansions, several of them installed heated driveways/sidewalks to eliminate shovelling. (My brother was the village engineer there for many years whose duties included permit inspections). It's clearly an extravagance, not a necessity, which is why it probably won't happen on public roads anytime soon. the cost might eventually come down but it is still cost-prohibitive given the scale required, there is also maintenance/repair/upkeep that is required. With so many states teetering on bankruptcy, I don;t see an investment of that magnitude will happen.

[Dattebayo]

A couple things:
First, are the solar panels part of the road surface or are they separate?
Second, if the panels are part of the road surface, did they adjust for cars actually being on the road and stopped traffic? As far as I see it, a vehicle (let alone enough to necessitate the word traffic...) will block the sun's rays and therefore reduce the amount of electricity produced...