France To Pave 1000km of Road With Solar Panels (solarcrunch.org)

An anonymous reader writes: France is planning on a project to build 1000 kilometers of road with specially designed solar panels. This project will supply 5 million people in France with electricity if it is successful. Though many solar experts are skeptical of this project, the French government has given the go-ahead to this venture. According to France's minister of ecology and energy, Ségolène Royal, the tender for this project is already issued under the "Positive Energy" initiative and the test for the solar panels will begin by this spring.The photo voltaic solar panels called "Wattway" which will be used in the project are jointly developed by the French infrastructure firm "Colas" and the National Institute for Solar Energy. The specialty of "Wattway" is that its very sturdy and can let heavy trucks pass over it, also offering a good grip to avoid an accident. Interestingly, this project will not remove road surfaces but instead, the solar panels will be glued to the existing pavement.

Comments

What could go wrong

[kamapuaa]

So basically the plan is to cover the pavement with glass, that will need to stay clean to let the sunlight through. I see no possible problem with any of this.

Re:What could go wrong

[Rei]

Meh, there's a solar bike path in the Netherlands and they don't seem to have excessive problems with dirt. Because rain exists. They got significantly higher generation than they were expecting - only about 1/3rd less than what you'd expect from rooftop mounted panels.

I too have criticisms of the "Solar Freaking Roadways", but let's start with common criticisms that aren't well grounded:

1) They'll scratch up: first off scratches can reduce light transmission but solar panels don't require good "optical quality", only transmission; the light is free to scatter on its way in. It's the same thing that applies to greenhouses - you may have noticed that many greenhouses use "fogged" plastic that you can't see through, yet still lets the vast majority of the light in (in that case, the scattering is actually seen as advantageous). Beyond that, in the case of roadways, I'd think it a given that they'd coat them with a an anti-scratch coat (aka harder than Mohs 7 / quartz sand, the hardest common natural material))

2) Traction: Traction glass exists - it's just surface texturing. They use it for semi-transparent flooring, it's nothing special.

3) "Glass would break and then shred tires": It's easy to make glass bear purely compressive loads (solid objects on both sides of it) without fracture - that's what it's best at. It's shear and tensile loads that glass is bad at, but these aren't applicable when it's flat on a hard surface. And lamination, like in windshields, prevents dangerous shards from coming off in the event of a fracture. This is not an actual limitation.

3) Shadowing: Go to Google Maps satellite view and look up random roads. The overwhelming majority of road surface is completely unshadowed at any point in time. Even in-city roads are overwhelmingly unshadowed. Shadows are practically irrelevant in the countryside except in wooded areas.

4) Costs: The costs of the materials for a road are a minority of the costs of the project, and continue to be a minority of the cost of the project under any realistic pricing for large-scale production of paving panels. A key driver for affordability, however, would be scale: this means large scale production (so road panels are similarly priced to rooftop panels plus the extra glass costs) and continuous paving systems. Anything smaller scale would have elevated costs.

5) "They'd be better on roofs": the main problem with roof installations is there is no way to do mass-scale continuous install (the sort of possibility that paving gives). Each roof has to be handled on its own, with its own engineering issues, with its own project overhead, its own inverters, etc. The key issue to cost reduction these days is getting rid of the overhead; panel production costs themselves have gotten quite low and keep going down. Furthermore, with a road you get "two birds with one stone" - a driving surface and a power generation surface built at the same time in the same space, sharing the same project overhead. It's fine to sacrifice some panel efficiency to glass, shadows, dirt, etc if it reduces your overhead costs.

All of this is not to say that I think they're inherently some sort of great idea that we should dump billions of USD into right this moment I simply think that they do deserve more development and testing, and I have issues with some of the criticisms that have been levied. On the other hand, I do have some issues with the "solar freakin' roadways" people. Number one on my list is the snow-melting concept. It takes five minutes to run the numbers on that and find that it takes way more energy than could ever be considered reasonable. You could melt thin layers of frost off the surface, but nothing of any relevant mass.

If one wants to pursue an anti-snow approach, my personal alternative is having an air bl

Re:What could go wrong

[Rei]

Even in heavy traffic, the overwhelming majority of the road is exposed. And yes, that's the 405, in a high traffic area.

Re:What could go wrong

[ShanghaiBill]

The vehicle-covered to not covered duty cycle on a rural highway is pretty high.

The duty cycle on rooftops is a lot better, plus there are no trucks driving over them there. I could see looking for alternatives once all the rooftops are full, but they are less than 1% covered so far. Ségolène Royal has a long history of advocating crazy policies with little thought about how to pay for them.

Re:What could go wrong

[ShanghaiBill]

I was just going to say that we, here in LA, were going to try this on the 405, but it's always covered with cars.

Here in San Jose, we have solar panels over many parking lots. They generate electricity while providing shade for the cars.

Re:What could go wrong

[currently_awake]

On most highways the cars only cover about 20% of the pavement. Unfortunately that's as good as this idea gets. It only makes sense to put solar panels where the cost of the panel is less than the value of the electricity, and roads isn't one of those places (armoured glass is expensive, they get scratched and dirty). Better places: a roof over the road (massive reduction in snow/ice removal costs, you can use cheap solar panels), on house roofs (you can use cheap solar panels), deserts (cheap land, lots of sun, cheap panels).

Re:What could go wrong

[jblues]

The duty cycle on rooftops is a lot better, plus there are no trucks driving over them there.

Trucks are constantly driving over my roof, you insensitive clod. I'm one of the last surviving trolls, and live under a (now solar paved) bridge.

Re:What could go wrong

[Rei]

Like how hold concrete becomes slippery? Yep, just like with concrete, you need to resurface. But one expects them to use anti-scratch coatings, which would significantly reduce the rate of wear. The aggregate in typical concrete can be up to Mohs 7, but the cement is only Mohs 2-5. Raw unprotected glass is Mohs 5-6,5, but scratch resistant coatings can raise it to over 7 to avoid being scratched by quartz sand.

Re:What could go wrong

[Elfich47]

Any given winter will have 50-100 freeze thaw cycles. Once you suggested air blower fails all of the nooks and crannies will get filled with snow and then the freeze/melt expansion/contraction cycle of water will destroy the piece of equipment. I have yet to see a piece of equipment that can stand up to repeated freeze/thaw cycles from a New England winter.

Next up: Snow plows and everything the snow plow pushes in-front of it. A snow plow lumbering along at 20 miles per hour can clear a path 15' wide and a foot deep (often more if it is the truck at the end of plow gang). Any odd ball things in the path of the plow get thrown aside - car parts, baby carriages, clothing, building supplies, will all be thrown aside.

Any portion of the solar panel that doesn't give a clean path to the plow will be destroyed. Any thing dragged along by the snow plow will leave tracks until it is thrown away. "Textured" glass designed to give better traction will get chewed on by the snow plows. If the snow plows leave chips, cracks or divots in the glass: the freeze/thaw cycle of water will attack those imperfections and widen them over the course of a winter.

Until someone demonstrated the ability of those things to survive several seasons of snow plows and freeze/thaw cycles I don't expect to see them where I live. Roadways are designed to be robust and not need a lot of maintenance (exceptions for specific specialty items are to be expected- bridges and tunnels come to mind).

Re: What could go wrong

[orlanz]

We could put it on all downhills in a certain grade range. Steal power from the brakes.

Also local roads with traffic that burn gas inefficiently should be ok too. They don't run the engine efficiently so stealing some excess power should be ok.

Re:What could go wrong

[Kjella]

A bike lane is nothing like a 50 ton truck in an emergency stop. Asphalt is extremely simple and can't be damaged in any meaningful way. Texturing and coating wears off, asphalt just wears down and if you're going to provide lots of traction as you must then there will be lots of wear. And you can't just make the wear layer thicker without reducing the optical properties. And if the foundation isn't rock solid these slabs are going to start wobbling and crack up like driving over giant tiles. And you can't rally patch a hole with a bit of cheap asphalt, the whole tile must out and be replaced. Cost is the big killer, it's why we don't use more solar today it's not like we covered everything else in solar panels and roads are our last resort. So they produce 1/3rd less energy, involve a ton of tempered, textured, laminated glass encased in concrete with high maintenance and low robustness. Where can I sign up?

tl;dr

[Anonymous Coward]

RRV #632 for the tech. For the political sorts, this is what happens when you have a stupid EU policy requiring the state to pay private companies to build infrastructure rather than employing their own talent.

Why not a roof?

[JoeMerchant]

Wouldn't it be more effective to build a "solar roof" over the highway, shading motorists during the hottest parts of the day, angling the panels to maximize insolation at the latitude, and for f's sake: not having to make them sturdy enough and grippy enough to safely drive trucks on them?

How long will this roadway last, and what will be the replacement cost? I mean, if this miracle surface can stop potholes from forming, then, yeah, let's put it everywhere, but I'm not feeling like that is the case.

Why?

[Dereck1701]

I can't really see the reasoning behind this, it would be far easier, more efficient, quicker and cost effective to put panels along the roadsides, next to substations on the sides of buildings, on roofs, or practically anywhere but on roads. Until they can lay solar panels like they do pavement for virtually the same cost as pavement there really isn't much point when there are SOOOOOOO many other viable locations.

Thanks France

[Kohath]

I don't think this will work, but I hope it does. I'm glad the French are paying to find out instead of us.

I suspect the initial cost (or yearly amortization of that cost) and ongoing maintenance of the solar panels will be higher than the value of the generated power.

1000km?

[Dutch Gun]

Wow... 1000km is a pretty hefty pilot program. And here's the important phrase:

This project will supply 5 million people in France with electricity if it is successful

So... 1000km and they have no idea if it's going to be successful? It seems like the reasonable thing to do would be to pave a few km of road and see how it holds up under real conditions for a few years. But hey, money is no object when you're saving the planet, right? Well, I'm glad it's their tax dollars that are doing a giant feasibility study for the rest of us.

The Dutch have the right idea. They've started with a 100m strip to start with to see if the things actually work as intended first. I like the concept, but new products and concepts like this need to be tested pretty carefully.

Good Video Outlining Technical Challenges

[Kunedog]

There was a successful kickstarter for something similar, which IMO gets ripped to shreds in this video:
https://www.youtube.com/watch?...

If you love solar panels, then why not put them, well, anywhere else instead of on a road surface where they will be under constant, severe assault by heavy vehicles with tires that can leave light-blocking rubber on them.

Doing this would be expensive and ineffective, if not impossible. It seems good for nothing but a scam to bilk investors or as another vacuous Green PR campaign.

Re:Good Video Outlining Technical Challenges

[Mr D from 63]

The one thing that is clearly missing from the article and reference pieces is an estimation of cost. There is no indication that this will be cost effective in any way. It would likely be much less costly to line roadsides and medians with normal panels.

But alas, for some, cost doesn't matter. It doesn't matter if we maximize the carbon reduction returns for our investments, it is more important to look like you are doing something extraordinary. Look at how wonderful the French are!

Slashdot: News for Haters

[Idou]

Seriously, of all the things to be bitching about in the world, this project seems like it should be low on the list, yet /.ers are foaming at the mouths by the look of the top comments right now. Even if this project is destined to failure, do you actually believe humanity will never, ever be able to capture solar energy from roads? Well, if you admit it might be possible one day, then guess what? It is going to take projects like this one failing to eventually get there (or did you think technological progress hatches like a magic egg if you wait long enough?).

A project like this is NOTHING compared to the money spent on fusion so far. Is it actually any more of a long shot than fusion? Seems like people who have trouble prioritizing their bitching list should not be so critical of how others are prioritizing their long shot energy projects. Besides, this has nothing to do with the project, and you are just blowing off steam because it is Sunday, and you couldn't get a date on Saturday night, AGAIN, right?

If only people could get rich off of pissing all over someone else's idea. . . /.ers could finally move out of their parents' basements and stop being such bitter a-holes. . .

Re:That is a REALLY BAD assessment

[Rei]

What road do you live near where the surface is packed full of rubber tire marks? Must be pretty miserable to live there, with people burning tires all the time.

A solar panel is in fact an EXACT OPPOSITE of a greenhouse - the greenhouse relies on IR alone,

Hahahaha.... oh geez... :)

Let's back all the way back to third grade and cover the topic of "photosynthesis". You see, plants need light from the sun to grow! Now class, take one of those seeds you sprouted and put it on your windowsill, and put the other in the closet... we'll bring them back to compare in two weeks. Don't forget to water!

The amount of light transmission is probably the biggest factor in greenhouse design. Here in Iceland people have to use glass (most common) or hard plastic (less common) because of the wind, thin plastic hoop houses don't survive here. Most commonly used is single pane glass. Yes, you read that right. Here in a country with "ice" in the name, it's still considered worthwhile to let the heat pour out of your greenhouse in order to get a few extra percent sunlight. Now, we have hot water for heating which reduces (but doesn't eliminate) heating costs, but still, it drives home the point: to growers, light equals growth.

Greenhouses most definitely do not rely on "IR alone".

If you're curious as to why fogged surfaces are often seen as desirable in greenhouses - it's because of shading. Fogging only causes the greenhouse to lose a couple to several percent of the light (depending on the type of plastic or glass), but it means that all of the light is no longer coming from the same angle. This helps get light to leaves that would otherwise be shaded by other leaves.

Ironically, contrarily to what you wrote, glass-covered solar panels do care about IR transmission. They don't generate power from IR, but their efficiency is correlated to their temperature, and the temperature is correlated with the radiative equilibrium of their environment.

Why roads?

[Firethorn]

Okay, first up: I analyzed the 'Solar Freaking Roadways!!!' proposals so I know the arguments, though I think they glossed over or ignored numerous problems. My end thought was that it might be a neat system for a pedestrian walk area, where you don't have anything bigger than a golf cart traversing it.

That being said, I'm always willing to be proven wrong - it's relatively easy to get me to agree to a 100m/1km/1 Mile or so 'test strip'. 100m, for example, is long enough to get a truck completely onto the solar surface and drive for a bit - because the interface might be a destruction point. Something to study, obviously.

Okay, the reasoning for 'solar roads' is a combination of displacement and synchronicity. By displacement, we mean that the surface of a properly constructed solar panel displaces other construction material - pavement, for a road. For something like a 'solar car park', solar panels are strong enough to replace the roof, not supplement it.
- Problem: Pavement is relatively incredibly cheap and durable.
Synchronicity: By this I mean that the substitution provides additional benefits. Solar roadways, for example, boasts that you could incorporate heating elements into their units such that when it snows you can avoid the need for plowing by melting the snow off the roads, then recoup the heat used via the solar panels. Problem - I don't think they've thought about heavy snows and that you get less light in winter.
Another 'benefit' would be using LED lighting to enable 'remapping' the control lanes on a road, signaling when it's safe to pass, etc...
They even said that the solar roads would be easier to repair - have a busted hexagonal panel? Pull up with a truck that has a robot arm that automatically unbolts and lifts the damaged panel and locks a replacement in. Each panel is supposed to be cheap because it's made in an automated factory.

As such, using the panels as 'roadway shade/shelter' such that things like rain and snow don't reach the road at all, and probably even block direct sun, is a much better use.