Solar friggn Roadways...from France

[Grottenolm85]

I just stumbled upon this website:
http://www.wattwaybycolas.com
Apparently they also build solar roadways, but in a simpler style. Their concept actually sounds technically possible, while still being economically rubbish.

Oddly enough they even acknowledge in their FAQ that their solution is about 3-times as expensive as conventional solar panels, while being less efficient (15% vs 19%).

Anyhow the french government decided to waste their money on this 

[AndreasF]

...
Anyhow the french government decided to waste their money on this 

And that's why it has been brought up already in 4 different places:

https://www.eevblog.com/forum/blog/eevblog-681-more-solar-roadways-bullshit!/msg854294/#msg854294
https://www.eevblog.com/forum/chat/this-thread-is-all-about-'publicly-funded-bullshit'/
https://www.eevblog.com/forum/chat/dave's-gonna-blow-a-gasket-or-two/
https://www.eevblog.com/forum/chat/they're-back-solar-roadways/

[dannyf]

If it is from France or Europe, it must be right,

Actually there is an article today about how centuries of Forest management in Europe have contributed to global warming.

Apparently, the wise european tree huggers have been planting the wrong trees all those years.

I didn't make that up, honestly.

[ivaylo]

If it is from France or Europe, it must be right,

Actually there is an article today about how centuries of Forest management in Europe have contributed to global warming.

Apparently, the wise european tree huggers have been planting the wrong trees all those years.

I didn't make that up, honestly.

At least you acknowledge there is global warming (albeit the French doing it by planting trees)...

[Brumby]

Actually, I think the only thing that was acknowledged was that there was an article written.  Not that they agreed or disagreed about the content.

[Grottenolm85]

I wonder who keeps  investing money in this stuff. As

If it is from France or Europe, it must be right,

Actually there is an article today about how centuries of Forest management in Europe have contributed to global warming.

Apparently, the wise european tree huggers have been planting the wrong trees all those years.

The trees growing in Europe today weren't planted against global warming. Most of those trees are about 60-70 years old...

[EEVblog]

An awesome article again by Joel Anderson on the French plan, including commentary from me:
https://www.equities.com/news/france-s-solar-roads-plan-a-costly-inefficient-boondoggle

[dannyf]

"At least you acknowledge there is global warming (albeit the French doing it by planting trees)..."

I thought it scientifically incorrect to say "global warming". " climate change" I think is the new term the climate scientists have asked us to use, in order to say their models.

As to global warming, I have been a believer of global warming for a long time, long before global warming was made fashionable: if you take a look at the long term temperature for the earth, you will find that our current temperature is significantly below average. That means if you believe in mean reversion, global warming is bound to happen.

Why does it happen? I have no idea, nor do any of those climate scientists.

[rrinker]

 Now there's a scary thought, where they say snowplow drivers should take extra care. Can you imagine of they caught the edge of one of these pieces and ripped up a whole stretch of the solar roadway? Ooops!

[EEVblog]

Why does it happen? I have no idea, nor do any of those climate scientists.

Yes they do, they're just smarter than you, and have spent their entire careers on it.

[dannyf]

"where they say snowplow drivers should take extra car"

Do they need snow plow on those roads? You are generating electricity right there and just some electric heaters and no snow accumulation.

[rrinker]

 DO solar cells work that way? I didn't think they did.

Mario Andretti, the race car driver, has a fancy block driveway at his house near here, which is pretty much impossible to plow due to it not being a flat surface. So he has water tubes under the whole thing, which when it's sunny out are used to heat his pool. When the weather turns bad, the warm water is piped under the driveway and keeps it free from snow.

[ivaylo]

"At least you acknowledge there is global warming (albeit the French doing it by planting trees)..."

I thought it scientifically incorrect to say "global warming". " climate change" I think is the new term the climate scientists have asked us to use, in order to say their models...

I just quoted you, man, this is what you wrote 

[tszaboo]

"where they say snowplow drivers should take extra car"

Do they need snow plow on those roads? You are generating electricity right there and just some electric heaters and no snow accumulation.

Now you are becoming ridiculous. If you have a normal roadway, the entire sunshine happiness is converted into heat. How would a solar panel powered heater beat that?
I really cannot decide if this is just bad trolling attempt or you really believe all the things you write.

[dannyf]

"I just quoted you, man, this is what you wrote  "

And that's because of what?

[tooki]

Now you are becoming ridiculous. If you have a normal roadway, the entire sunshine happiness is converted into heat. How would a solar panel powered heater beat that?

That is precisely the argument I've made. If snow collects on black asphalt, which is a more efficient energy collector than a solar cell can ever hope to be, by what mechanism would the losses at step in electric solar heating be not only recovered, but exceeded?

The only way thing one could possibly accomplish is to concentrate a whole road's energy onto melting snow from just one small section of pavement. (E.g. large solar parking lot melting snow just on the sidewalk.)

[dannyf]

"snow collects on black asphalt, which is a more efficient energy collector than a solar cell can ever hope to..."

I am pretty just about anything is more efficient to collect energy from the sun than black ashphalt covered by prestine white snow.

The fact that it is to be pointed out is sad.

[tooki]

Ummm... And how would a solar pavement not become equally covered in snow? You seem to be failing at even the most rudimentary logic, sorry.

[zapta]

Yes they do, they're just smarter than you, and have spent their entire careers on it.

If they know it is not reflected in their failed models and predictions (referring to the IPCC crowd).

Focusing on authority and career length is bad science.

[dannyf]

"And how would a solar pavement not become equally covered in snow? You seem to be failing at even the most rudimentary logic, sorry."

So we have established that that wonderful black asphalt covered in snow isn't that wonderful at melting snow.

Now, we can refocus you at understanding how snowplow may not be necessary with our solar walkway: what energy source do you think the solar walkwaybis connected to? Would it be too difficult to envision utilizing that energy source to melt snow fall on the solar walk way?

Think about it for a second I think the answer will come to you.

[tszaboo]

"And how would a solar pavement not become equally covered in snow? You seem to be failing at even the most rudimentary logic, sorry."

So we have established that that wonderful black asphalt covered in snow isn't that wonderful at melting snow.

Now, we can refocus you at understanding how snowplow may not be necessary with our solar walkway: what energy source do you think the solar walkwaybis connected to? Would it be too difficult to envision utilizing that energy source to melt snow fall on the solar walk way?

Think about it for a second I think the answer will come to you.

It came to us, but we are equipped with basic common sense.
You need a lot of energy to melt snow. I saw 300W/m2 figures, to melt 4cm of snow per hour (if the temperature is 0 degrees). After you melted, you got some that awful efficiency system, which is even handicapped becuase it is winter, it was about 7% peak of the nominal capacity (today, here) for something like 10W for the same size, for 8 hours. Even with best calculation, you need days to melt 4 cm snow. If the temperature is below 0 degrees, the numbers are even worse.
And you actually need to clean the road, because of cars.
And snow has to be melted evenly, across the entire size, otherwise you loose your efficiency even more.

[electr_peter]

Road heating is a terrible idea. I do not know why it is even discussed. Some issues with this idea, just to name a few:

• It is very inefficient and costly way to remove snow build from the roads. On top of that, most energy are simply wasted to environment without even melting the snow. Consider very high specific heat of ice/snow/water. Snow plows is the way to go.
• Snow is less of a problem than ice for roads. Heating can convert snowy road to icy road - not good at all.
• Most issues with too much snow are experienced in rural and remote areas - both due to lower maintenance and lower traffic intensity. Heating massive road areas in rural areas makes no sense whatsoever. On the other hand, urban roads with high traffic heat up slightly from passing cars and have more snow plows passing rendering additional heating useless.
• Cost wise it is much more efficient to use snow-plows with salt mixture. Also, proper winter tires (soft compound or with metal studs) on all 4 wheels must be installed (not that all season tire rubbish).

Road heating can work (some people are heating their driveways; some pavements are heated in city centres), but it is very costly, inefficient and cumbersome to implement. It is pretty obvious to people living in colder climate and experience with snow/ice on roads.

[tom66]

"At least you acknowledge there is global warming (albeit the French doing it by planting trees)..."

I thought it scientifically incorrect to say "global warming". " climate change" I think is the new term the climate scientists have asked us to use, in order to say their models.

Both global warming and climate change are valid.

Global warming happens as a whole. Climate change is the result of global warming: local temperatures may rise or fall independently but global average temperatures will slowly go up. Similarly weather patterns may change. They may get worse (increased rain in flood prone areas; less rain in drought prone areas etc.) or potentially get better, but it is very hard to say with any significant degree of accuracy what will happen. Rather, it is just an insanely bad idea to put ourselves in the same test tube whilst figuring out what tweaking X may or may not do to Y.

I'm pretty sure this has been explained to you hundreds of times and so I can only guess you keep repeating this nonsense is it supports your point of view that scientists are in on some kind of global conspiracy or something like that to lie to everyone about AGW (anthropogenic global warming.)

[tooki]

"And how would a solar pavement not become equally covered in snow? You seem to be failing at even the most rudimentary logic, sorry."

So we have established that that wonderful black asphalt covered in snow isn't that wonderful at melting snow.

Now, we can refocus you at understanding how snowplow may not be necessary with our solar walkway: what energy source do you think the solar walkwaybis connected to? Would it be too difficult to envision utilizing that energy source to melt snow fall on the solar walk way?

Think about it for a second I think the answer will come to you.

The energy source of a solar panel is light. The output the panel connected to is the power grid, but if we need to use that to power the heaters, then by definition the solar walkway is consuming more energy than it's producing. That's just idiotic.

[dannyf]

The energy source of a solar panel is light. The output the panel connected to is the power grid, but if we need to use that to power the heaters, then by definition the solar walkway is consuming more energy than it's producing. That's just idiotic.

So your house with a solar panel also takes energy from the grid, from time to time. Does that make the homeowner idiotic for putting the solar panel there?

I guess I was over-confident in your thinking capabilities.

[tooki]

So your house with a solar panel also takes energy from the grid, from time to time. Does that make the homeowner idiotic for putting the solar panel there?

Apples and oranges. Regardless of where you put a solar cell, using another form of energy to melt snow off of it is just moronic. Stupid. Idiotic. Pointless. You are putting in more energy than you're getting out. You'd be better off not bothering at all. Why would you spend $1 to earn 15¢?

I guess I was over-confident in your thinking capabilities.

There certainly is someone among us two who's overconfident in their thinking ability, but it's damned well not me. I'm not the one arguing in favor of putting in more energy than you'll get out. 

[tszaboo]

So your house with a solar panel also takes energy from the grid, from time to time. Does that make the homeowner idiotic for putting the solar panel there?

Apples and oranges. Regardless of where you put a solar cell, using another form of energy to melt snow off of it is just moronic. Stupid. Idiotic. Pointless. You are putting in more energy than you're getting out. You'd be better off not bothering at all. Why would you spend $1 to earn 15¢?

I guess I was over-confident in your thinking capabilities.

There certainly is someone among us two who's overconfident in their thinking ability, but it's damned well not me. I'm not the one arguing in favor of putting in more energy than you'll get out. 

I think he just turned from semi troll to full blown troll. This happened before. Wonder when the ascii art comes.
6500 forum post, and probably 95% is not helpful.

[zapta]

I'm pretty sure this has been explained to you hundreds of times and so I can only guess you keep repeating this nonsense is it supports your point of view that scientists are in on some kind of global conspiracy or something like that to lie to everyone about AGW (anthropogenic global warming.)

Tom, we had in the last century few cases were science was corrupted to drive political agendas, for example  with eugenics and Lysenkoism. 

As the models and predictions of human-co2-emmision-induce-catahstropic-global-warming keep diverging from reality while activists and politicians keep ignoring the evidence, suppressing decent, and use it to justify political agendas, this has all the signs of a similar case

The good news is that like any time bound prediction it cannot go forever. When think sink also with you, probably in the next 10-25 years, please say to yourself, hmm, dannyf was right.

[suicidaleggroll]

Apples and oranges. Regardless of where you put a solar cell, using another form of energy to melt snow off of it is just moronic. Stupid. Idiotic. Pointless. You are putting in more energy than you're getting out. You'd be better off not bothering at all. Why would you spend $1 to earn 15¢?

You're joking, right?

Depending on the atmospheric conditions, the panel could produce significantly more power once the snow is gone than it would take to heat it and melt the snow, versus just sitting around and waiting for days/weeks for the snow to melt off on its own.

We're talking maybe a kW for an hour to melt off the snow from a kW panel.  It would make back that power in 1-2 hours once the snow is gone, and after that it would be in the green.  Compared to sitting around and waiting for a week for the snow to melt off on its own, it's a no-brainer.

Note I'm just making up these numbers, but I find it VERY difficult to believe the panel wouldn't be able to recover as much and more power once the snow is gone than it took to melt it, compared to sitting around and waiting.

[tszaboo]

Note I'm just making up these numbers, but I find it VERY difficult to believe the panel wouldn't be able to recover as much and more power once the snow is gone than it took to melt it, compared to sitting around and waiting.

Except I've run the numbers and you need days to melt just freezing snow. See the numbers above.

[suicidaleggroll]

I saw your calculations, and I still don't see why you think it's so ridiculous.

300 W/m^2 to melt 4 cm of snow in an hour, it sounds reasonable.  A 1 m^2 panel would be rated at around 200 W.  In the winter it will be less, you said 7% for 8 hours, let's go with that.  7% of 200 W for 8 hours is 112 Wh per day.  So if it snowed 4 cm, and you put in 300 Wh/m^2 from the grid to melt it so that you could start generating power again, you'd break even after two and a half days.  I don't know about where you live, but when it snows 4 cm here, it typically sticks around for longer than 3 days.  It could be a week before the entire panel was clear again.  If you just sat around and waited for it to melt off on its own, you'd end up losing more energy than if you melted it off-the-bat and let the panels start working again.

This isn't always the case of course, sometimes it snows here and is 70 F the next day, in that case it would be better to wait.  But just dismissing the approach entirely as "moronic, stupid, idiotic, and pointless" as tooki said, is incredibly short-sighted in my view.

[dannyf]

latent heat of water/ice is 330Kj/kg. A 1Kw heater will output that much energy in about 330 seconds, or 6 minutes. Or for 0.1kwh, a heater can convert 0c ice to 0c water (melting it). More to heat it up.

I pay my guys 150usd per snow plow, 2x or 3x of that for heavy snow. @ 10 cents per kwh, that much money would allow me to melt about 150/0.1/0.1 = 15ton of snow.

I don't think I ever get anything close to that.

We actually explored putting electric heaters under our driveway for that purpose. The installation cost ($90K for our driveway) was deemed too expensive. I would consider it at maybe $25K or less: no plow, no salt, no 4wd/awd vehicles, and always-driveable driveway would be a big plus for me and the next buyer.

[tszaboo]

I saw your calculations, and I still don't see why you think it's so ridiculous.

300 W/m^2 to melt 4 cm of snow in an hour, it sounds reasonable.  A 1 m^2 panel would be rated at around 200 W.  In the winter it will be less, you said 7% for 8 hours, let's go with that.  7% of 200 W for 8 hours is 112 Wh per day.  So if it snowed 4 cm, and you put in 300 Wh/m^2 from the grid to melt it so that you could start generating power again, you'd break even after two and a half days.  I don't know about where you live, but when it snows 4 cm here, it typically sticks around for longer than 3 days.  It could be a week before the entire panel was clear again.  If you just sat around and waited for it to melt off on its own, you'd end up losing more energy than if you melted it off-the-bat and let the panels start working again.

This isn't always the case of course, sometimes it snows here and is 70 F the next day, in that case it would be better to wait.  But just dismissing the approach entirely as "moronic, stupid, idiotic, and pointless" as tooki said, is incredibly short-sighted in my view.

Because if te temperature is -5 degrees, then you need a lot more than 300W. And you need to clean the entire road. Even if one cell is shaded, it drops the efficiency by a lot. And it is a solar roadway, so it will not generate as much as you wrote.
And solar roadway is idiotic alone (as long as roofs are free), you dont need the heating for it to become idiotic.

[Galenbo]

Anyhow the french government decided to waste their money on this 

No, the powers-that-be decided to waste other people's money on this.

On this forum it's all about efficiency in engineering terms and units, for them it's also about efficiency, but in political units and terms.
Those who benefit from the story are the contacts of the lobby groups, fabricants, "study departments" at universities, new project managers,...

And the ones who have to pay? They can re-elect the same type/class of politicians the next time. And they will.

Big pusher this time is Ségolène Royal from PS socialists, by "the poor" given the position "France’s minister of ecology and energy"
Well, another reason to never feel pity again for "those poor". They are "poor" because they personally caused it, and now they deserve it.

[dannyf]

"Because if te temperature is -5 degrees, then you need a lot more than 300W. "

Because it is highschool level physics so not everyone knows this but ices latent heat is about 160+ degrees higher than its specific heat.

To put it in middle school language, it takes more energy to turn 0c ice to 0c water than to heat -160c ice to 0c ice.

Hope it helps.

[tszaboo]

"Because if te temperature is -5 degrees, then you need a lot more than 300W. "

Because it is highschool level physics so not everyone knows this but ices latent heat is about 160+ degrees higher than its specific heat.

To put it in middle school language, it takes more energy to turn 0c ice to 0c water than to heat -160c ice to 0c ice.

Hope it helps.

Yes. If you ignore heat transfer. Which you just did. And the heat dissipated on the bottom. And the fact that the entire conception of solar roadway is ridiculous. And the fact, if melting snow for solar panels would make sense, they would make it, you know, on those which are on the roof. They dont make it for some reason, I wonder why? They dont make it on dedicated, motor controlled solar panels. Because it is not economic, or because everyone except you has less than high school level knowledge about stuff?
Now can we stop being stupid and discuss the topics as engineers?

[dannyf]

" can we stop being stupid and discuss the topics as engineers?"

Kind of difficult, with someone who apparently doesn't understand latent heat vsm specific heat.

[tszaboo]

" can we stop being stupid and discuss the topics as engineers?"

Kind of difficult, with someone who apparently doesn't understand latent heat vsm specific heat.

On the plus side, you just made it to my ignore list first. Congratulations, you are first!

[dannyf]

Unlike you, I never ignore morons.

[BillyD]

Unlike you, blah blah blah blah blah blah

No point in addressing him directly; he has ignored you.

[Galenbo]

Unlike you, I never ignore morons.

No point in addressing him directly; he has ignored you.

No point in quoting him, this way the ignore function is bypassed :-)

[EEVblog]

I have a video mostly shot on this.

[BillyD]

blah blah blah blah.

No point in addressing him directly; he has ignored you.

No point in quoting him, this way the ignore function is bypassed :-)

Oops you're right, never thought of that! Oh the irony, lol!
However I will go back and de-troll my quote. Thanks!

[zapta]

Oops you're right, never thought of that! Oh the irony, lol!
However I will go back, misquote dannyf and eat three bananas.

+1

[electr_peter]

One has to guess motives of forum member with 6k+ posts who still does not use proper quote functionality (which is very easy to use on this forum) and removes forum user names from quotes on purpose...

Regarding the snow heating and why it is such a bad idea. During cold season days are shorter, sun is lower in sky and much less heat from sun is available. Also, weather is generally cloudy before and after snow. Where would electricity come during such time? Who would pay for it? And for what purpose?
To summarise - in winter it is generally too cold, too dark, very energy inefficient to heat roads in order to clean them from ice/snow. Various subtle thermal effects of snow would make "road heating" worthless and dangerous idea for general purpose roads. Try it yourself and see how "easy" it is to melt the snow.
All of this is especially true when road solar panels are added.

[miguelvp]

One has to guess motives of forum member with 6k+ posts who still does not use proper quote functionality (which is very easy to use on this forum) and removes forum user names from quotes on purpose...

I don't know, maybe is because he wants to respond without telling others who posted quote, as in no finger pointing?
The person being quoted will know it was his/her quote.

Anyways, some people like to do things differently, I do get that the quotes can be out of context and is harder to find the context they were in, but I for one don't mind his style, or others that put the quotes after their replies.

Myself I do prefer the norm, maybe is because I work with large teams so I tend to use the style of the code at hand. But that's just me, some people will use our current coding standard but that doesn't help.

Regarding his statement, maybe someone missed that he said "it takes more energy to turn 0c ice to 0c water than to heat -160c ice to 0c ice."

Meaning before requiring the phase change from solid to liquid with will require 334 kJ per Kg of ice which is endothermic.

I'm not going to do the math, but his statement says, that going from -160C ice to 0C ice will use less energy that 334 kJ/Kg. I have no reason to doubt that is true.

Actually I'll do the math, Ice specific heat capacity is 2.108 kJ/kg-K, multiplied by the temperature delta, since we are just using 1Kg of ice, is 337.28 kJ/Kg, so he was wrong after all because he rounded up 158.444 to 160.

[roffvald]

First stretch of Solar Roadways in France has apparently been opened...

https://www.cnet.com/news/worlds-first-solar-road-opens-in-france/

[Ampera]

There are two types of people in this world

There are proper engineers that understand the requirements and implications of solar roadways

And then there are the politicians that need to throw their approval ratings up with false hope and flashy garbage.

[Watth]

Well, if we could harvest energy from facepalming, Ségolène Royale (the current ecology minister in question) would provide most of France's power. Lately she was criticized for being a bit too enthusiast about Castro's legacy, at his funerals.

[Falkra]

More and more BS, right ?

It was on the news, and there was another example of energy made from a green sidewalk which could make electricity from footsteps (in a big avenue). This looked 1000x better than... this.

[nctnico]

As G.W. Bush would say 'The French have no word for charlatan'. 

[Falkra]

Hehe.