Solar FREAKIN' roadways discussion

[Seret]

Are the solar cells more efficent because they are in the road rather than on a roof?

Somewhat less, ideally you want to incline them towards the horizon.

[Nibb31]

Unused space. That's why.

That's a poor reason. There's lots of unused space on rooftops, water, fields...

[Red Iron Crown]

Seems to me like it would be better somewhere where vehicles aren't driving over them. Tempered glass is strong but not indestructible, and I have doubts about their longevity anywhere snow must be plowed (not to mention they're less effective when covered in snow).

Large scale solar is a good idea that faces many challenges but I'm not sure available space is one of them, at least in North America.

[PakledHostage]

There's a really, really good reason that AC won-out over DC when it came to power transmission along electrical cables, and that's that it requires half the bloody cable. For DC to work, you need a continuous, closed circuit (just like in a land-line phone). For AC, you just stick one end into the ground instead.

AC also has the advantage that it is easy to tap into the line with transformers to provide useable power to electricity consumers.

DC does have some advantages when transmitting power over longer distances, such as lower line losses. HVDC Vancouver Island is a transmission line system between the BC mainland and Vancouver Island that rectifies AC to DC prior to transmitting it through undersea cables to the island.

[N_las]

Pros:

Microgeneration of clean electricity at a local level.

Already co-located with support infrastructure.

Generates an income.

Integrates heating for cold climates.

Integrates signalling or marking into road surface.

- Couldn't you "microgenerate" the electricity better, if you put the solar cells not under the road?

- Wouldn't solar cells produce a better income if they are directly in the sun?

- They want to heat the roads? In the winter, if there is around -10°C outside, you want to keep the roads heated to a bit over 0°C? That is insane.

- What is the advantage of integrated light signals? It sounds like integrated signaling on my bedsheet: What does it provide?

[maccollo]

Are the solar cells more efficent because they are in the road rather than on a roof?

You loose about 30% efficiency because you can't actively track the sun. and then you loose even more because they lay flat on the ground.

How much depends on your latitude and season. Losses can range from just a few percent to near total loss.

Solar panels you put on the roof can't activly track the sun either, and the angle is often not optimal, but it's far better than just having them flat on the ground.

Solar roads will also have this problem:

http://1.bp.blogspot.com/-37_o4_CpEZg/Uba2YsyrTvI/AAAAAAAAEKY/jVw3lV0baI4/s1600/Seamless+dirty+road+asphalt+tarmac+texture.jpg

The amount of dirt varies depending on the surroundings but you will nearly always find dirt in the groves and creases, and it is completely opaque,

so you loose even more efficiency there. Then you will get scratches, and dirt will be pressed into those you will have a very hard time getting it out.

Finally, the PVs don't cover the entire brick.

When you multiply all of these losses you get pretty abysmal efficiency compared to using the same solar panels on a solar farm.

Edited June 10, 2014 by maccollo

[AngelLestat]

Solar road seems like a very bad idea.

I am agree with the Seret´s Cons list as some others, and I want to add maintenance.

There is no 1 km of road in the world which does not wroke by trafic and climate conditions every 1 or 2 years.

The future of solar sails remains in buildings, dedicated plants, in space, etc.

One other thing, how much cost and time you would need to remplace at least the 20% of roads with this technology?

When you do that, almost all vehicles would fly.

[jwenting]

Cons:

High upfront cost.

Reliability is unproven.

Safety under real traffic conditions is unproven.

Many roads are not ideally oriented for solar generation, especially in city centres with shading issues.

Not clear if they'll be available from more than one supplier (what parts of the design are protected?).

The panels are flat, which could be an issue for drainage and camber.

I'm sure there's more of both, but those are the ones that leap to my mind.

excessive maintenance cost.

any rain, snow, dust storms, rubber residue, traffic jam, etc. etc. is going to seriously reduce output.

they're rather slick, so lots of slipping and sliding cars, lots of accidents.

[Seret]

- Couldn't you "microgenerate" the electricity better, if you put the solar cells not under the road?

Yes, but the whole point of the project is that the roads need replacing anyway. In the US there seems to be a bit of a funding crisis to get this done, so the idea is to resurface them with something that generates income, instead of just being a cost. Conventional roads are surprisingly expensive.

- Wouldn't solar cells produce a better income if they are directly in the sun?

Yes. The best performance comes from tracking the sun directly, although fixed panels inclined at an angle are generally more cost-effective. Shading is bad for solar arrays, although less of a problem if you use microinverters.

- They want to heat the roads? In the winter, if there is around -10°C outside, you want to keep the roads heated to a bit over 0°C? That is insane.

The roads have to be kept clear anyway. Heating is a solution used in some places already (some of the Nordic states use it IMO, presumably tied into their district heating systems and using waste heat from power plants).

- What is the advantage of integrated light signals? It sounds like integrated signaling on my bedsheet: What does it provide?

Tbh it just seems like bling to me, although it could be handy to have road markings that could be controlled externally. Variable speed limits could be shown, weather and traffic warnings, etc. In short all the stuff you'd normally use a separate sign at the side of the road.

excessive maintenance cost.

Too early to say, it's still in R&D. The inventor doesn't even have a unit cost yet, let alone the lifecycle costs.

any rain, snow, dust storms, rubber residue, traffic jam, etc. etc. is going to seriously reduce output.

Indeed. It needs multi-year test under real road conditions to get an idea of output over time.

they're rather slick, so lots of slipping and sliding cars, lots of accidents.

They're engineered to give good traction, this isn't a biggy IMO. If they didn't provide a tractive surface at least equal to current roads they wouldn't be fit for purpose. Obviously they'd have to pass the kind of safety tests regulators would impose on any new road surface material.

[Dodgey]

Yea. Need I say more?

[Seret]

Yea. Need I say more?

Some of his points are perfectly correct, but some of it is also nonsense. His initial point about the LEDs is particularly silly, as is his "experiment" where he uses an ordinary glass bottle to prove that glass couldn't be engineered to the required spec. It's like using the fact that you can bend a teaspoon to prove that steel is unsuitable for building skyscrapers.

I'm still not convinced that the idea will result in a practical product, but the backlash against it has been somewhat shrill and incoherent too. That probably not helped by the shrill and incoherent tone of the viral "Solar freakin roadways" video produced by a fan of the technology.

[N_las]

Yes, but the whole point of the project is that the roads need replacing anyway. In the US there seems to be a bit of a funding crisis to get this done, so the idea is to resurface them with something that generates income, instead of just being a cost. Conventional roads are surprisingly expensive.

Yes. The best performance comes from tracking the sun directly, although fixed panels inclined at an angle are generally more cost-effective. Shading is bad for solar arrays, although less of a problem if you use microinverters.

So rebuilding the roads with standart methods and simultaniously building solar panels somewere else on a fixed angle will be a better solution. The logic: "Roads should generate income -> we build solar panels inside the roads!" sounds as dumb to me as "Roads should generate income -> we build pizza ovens inside of them"

Building pizza ovens (or solar panels) somewere else will generate MORE income than in the roads. Income is income, just because it isn't generated in the roads doesn't mean it can't be used to mantain the roads.

The roads have to be kept clear anyway. Heating is a solution used in some places already (some of the Nordic states use it IMO, presumably tied into their district heating systems and using waste heat from power plants).

But keeping the road at over 0°C while snow falls on top of it? During the whole winter? If the energy generated by the solar energy would be sufficient for that, than the roads would be snow free automatically, because the sun would already melt the snow. So more energy is needed for keeping the roads ice free, than the sun can provide.

Tbh it just seems like bling to me, although it could be handy to have road markings that could be controlled externally. Variable speed limits could be shown, weather and traffic warnings, etc. In short all the stuff you'd normally use a separate sign at the side of the road.

The same thing can be achieved with just a few LED signs. Making the whole road a giant LED sign doesn't make sense. My alarm clock has a LED display. But why should I put LEDs all over my Room for the same purpose?

[maccollo]

he uses an ordinary glass bottle to prove that glass couldn't be engineered to the required spec.

He uses borosilicate glass, which has a factor of 7 on moh's hardness scale. So it is very tough glass, as tough as the gorilla glass used in some smart phones.

It failed miserably.

[ZedNova]

Has anyone else also thought about hacking them? They're going to be using some sort of Wi-FI technology to communicate with one another. And communication between electronics requires software.

I'm not really concerned about anyone stealing them, as the prototype weighs around 50Kg.

Edited June 10, 2014 by ZedNova

[Seret]

So rebuilding the roads with standart methods and simultaniously building solar panels somewere else on a fixed angle will be a better solution.

The point is that there's not enough money in the pot to replace the current roads, so there certainly wouldn't be enough to replace them and pony up for a whole lot of gucci PV arrays on top. The problem seems to be that America is big, and Americans have paved over more of it than they can now afford to maintain.

But yes, if you could just take the road budget and instead spend it on sensibly sited and emplaced solar arrays you would indeed generate more power than a solar roadway. That's not really the point though.

But keeping the road at over 0°C while snow falls on top of it? During the whole winter?

Presumably only when weather conditions demand. There's no intention to power this from solar energy, insolation during winter is too low for that anyway as you correctly point out.

The same thing can be achieved with just a few LED signs. Making the whole road a giant LED sign doesn't make sense.

I'm inclined to agree, I think the integrated lighting is somewhat superfluous. But the idea is worth investigating even without it. The practicality of a solar roadway will depend on whether they can solve the materials and integration challenges at the right price. The integrated lighting feature is just a sideshow IMO. If it works, great. If not, who cares? Dropping it would just make the panels simpler and cheaper.

Edited June 10, 2014 by Seret

[sgt_flyer]

I think piezoelectric roads might be more interesting (at least in zones with a lot of traffic, like cities)

Converting traffic generated vibrations into electricity

[Seret]

He uses borosilicate glass, which has a factor of 7 on moh's hardness scale. So it is very tough glass, as tough as the gorilla glass used in some smart phones.

It failed miserably.

Hardness and toughness aren't the same thing. The problem is that if you increase a material's resistance to scratching (plastic deformation) you tend to lose toughness (resistance to fracture) and vice versa. The surface for this road would have to perform really well at both, and it's not clear if a material with high enough performance is available, or if it would be affordable. This is an R&D project, they're still looking to invest in materials development. The whole project hinges on whether they kind make a good enough glass. I wouldn't like to say they can't, I'm no expert but glass technology has been advancing quite steadily lately. Who knows?

[Dodgey]

Here is another video he made about it. As maccollo said, he used borosilicate glass. Being a very hard glass comparatively it stands to reason that it would be a good choice to stand up to the ware of being driven on, except glass shatters and scratches.

Edit

That's the main problem. They don't have a material that they can use. But this is only the matériel that covers the road and I'm not convinced that's the biggest of their problems.

Edited June 10, 2014 by Dodgey

[Red Iron Crown]

Transparent aluminum is the obvious solution. We need a Scottish engineer who's looking to make a whale tank.

[vger]

Transparent aluminum is the obvious solution. We need a Scottish engineer who's looking to make a whale tank.

That's been done already, actually.

[AngelLestat]

This idea reminds me the Footstep electrical generator

In this case, you can let 500 people walk over and you will only get enoght energy to iluminate a bathroom for a few mins.

I can not understand how people waste time to develope these useless inventions, they dont see the flaws?

In my first reply I was not sure how they plan to use the road like solar panel, now I realize that is more silly that I thought.

Also the energy waste that you get in the manufacture of all these components and materials is just much more that you can generate over their lifespam.

I always read A LOT about sustainability and renewable energy (that is my passion), there are a lot of ways to improve the efficiency of all our processes and energy generation using renewable, being cost effective or even cheaper than fossil fuels / nuclear.

But no this nonsense.

In fact, these ideas are so bad that make people lose faith in renewable energies.

Edited June 10, 2014 by AngelLestat

[Dodgey]

That's been done already, actually.

But it isn't very cost effective for this application.

[Aethon]

Wow. Just read the dev.notes and kinda feel like anything anybody says right now is anticlimactic ( if you haven't read HarvesteRs' article, go there now ), but 20 min. ago I thought this was pretty amazing.

7 Min.

http://blog.petflow.com/this-invention/#UOl9CsSFBS4iDTqC.01

[cantab]

*sigh*

Not this one again.

Like so many "amazing" ideas, it's got a ton of problems.

[Spartwo]

This was a thread about a week ago.