Solar Road Ways

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Kharthulu
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Solar Road Ways

Postby Kharthulu » Wed May 21, 2014 5:12 am UTC

I did a search on the forums looking for somebody already talking about this and since i didn't find it, i felt i should tell you guys about it.

There is a small starting company. Their intention is to make it possible to convert all the road ways in america into solar panels. They assert that these panels can withstand the weight of the heaviest trucks, and provide the traction required, and they are also equipped with LED lights which can be programmed for many things, and heated so that any snow that falls will melt, thus getting rid of the need for salting roads or using snowplows. They assert that if this was done, it would generate 3 times as much power as the united states currently uses. Which would eliminate the feed for fossil fuel driven energy production, and would facilitate a wholesale conversion to electric vehicles totally a 75% reduction in america's carbon footprint.

Here is their website: http://www.solarroadways.com/intro.shtml
And here is the video some crazy person made to make the sell on these things more fun: https://www.youtube.com/watch?v=qlTA3rnpgzU

Do with it what you will.

billy joule
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Re: Solar Road Ways

Postby billy joule » Wed May 21, 2014 7:25 am UTC

It's a nice thought but...

Is american that land poor that you need to tear up all your roads and lay really expensive solar panels?

I mean have you run out of room for conventional solar power plants?

I can't think of a more inconvenient place to put solar panels :?

Would you put them down shady streets? What about high traffic flow roads where vehicle shading is high?


I assume having a power source thinly spread over the entire country would need massive infrastructure (HV transformers every few km I assume) and would have high transmission losses.

Kharthulu
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Re: Solar Road Ways

Postby Kharthulu » Wed May 21, 2014 11:28 am UTC

Keep in mind that we constantly rebuild our roads. We wouldn't need to actively tear up road to lay this stuff down, we just need to wait for a rebuild cycle and after the tear up the old damaged road, just lay this down instead. And we can build solar panels our in the middle of no where, but the power would be more accessible and easier and less costly to transport if it was literally made in front of your house or business.

stoppedcaring
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Re: Solar Road Ways

Postby stoppedcaring » Wed May 21, 2014 2:29 pm UTC

Do they have a straightforward cost analysis anywhere? I'd want to see numbers.

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Re: Solar Road Ways

Postby Kharthulu » Wed May 21, 2014 3:56 pm UTC

Not yet. They say they'll have those numbers in july. I admit, that is what this is all dependent on. We need to know how much they cost versus traditional roads and how long they last versus traditional roads. It might afford tons of savings overall, but people aint gonna go for it unless it's reasonably close to the cost of traditional roads and last at least as long.

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Re: Solar Road Ways

Postby stoppedcaring » Wed May 21, 2014 4:29 pm UTC

Kharthulu wrote:We can build solar panels our in the middle of no where, but the power would be more accessible and easier and less costly to transport if it was literally made in front of your house or business.

I can second this. The cost of establishing new right-of-way easements to transport electricity from random areas to where it's needed is high. If the road IS the easement...well, there you go.

This would have to be free market in order to function, though. E.g., the government pays a private company to resurface the road (at roughly the same price as it does now) but the private company invests capital to resurface using these panels rather than asphalt. The company then owns the electricity-producing capacity of the roadway and sells the electricity into the public grid.

A federal government subsidy would be fine, but a tax break would be better. E.g., no taxes on profits from green energy for the first 20 years. Let's not have the government try to actually fund the thing from the ground up, though. That would be a disaster.

Kharthulu wrote:Not yet. They say they'll have those numbers in july. I admit, that is what this is all dependent on. We need to know how much they cost versus traditional roads and how long they last versus traditional roads. It might afford tons of savings overall, but people aint gonna go for it unless it's reasonably close to the cost of traditional roads and last at least as long.

Right. Cost per standard mile, predicted cost decrease for larger installations, amount of electricity it can produce, lifespan, environmental impact of discarded panels, impact on precious metal supply. Plus, logistics. Compatibility with tires. What happens if there's a motor vehicle accident? Can it hold up to grit and road grime? All of that sort of stuff.

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Whizbang
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Re: Solar Road Ways

Postby Whizbang » Wed May 21, 2014 6:02 pm UTC

I imagine grit and road grime would quickly reduce the efficiency of these panels. We don't see it because black tar on black tar doesn't show up very well, but our tires are constantly leaving a very thin residue behind when we drive, hence balding tires. A single car doesn't leave much, but a busy road will quickly get covered, at least where the tires most often go, blocking the light to those tiles. I bet that the tiles would be best served on the shoulders of the road and between each lane.

Another thing is potholes. Currently, we can just patch the hole using some cold/hot patch, and once the road gets bad enough then we repave. What do we do with the potholes if we switch to solar panels? Can we continue to use the same patching materials?

What about frost heaves? Here in New Hampshire, the road heaves quite a bit during late winter. The road just kind of bends with the heaves, though there are also tons of cracks and holes that form. Can these panels bend the same way as asphalt?

What about theft? If I go out and pry up a few panels, can I supplement my home electric? I imagine there would be some people more than happy to swipe a few tiles, stick them in their backyard, connect them up to their home, and get free energy. Currently, asphalt is theft-proof. It has no value outside of the road. Energy, though, has a high value (though it would likely drop if this plan went into effect).

stoppedcaring
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Re: Solar Road Ways

Postby stoppedcaring » Wed May 21, 2014 6:45 pm UTC

Whizbang wrote:I imagine grit and road grime would quickly reduce the efficiency of these panels. We don't see it because black tar on black tar doesn't show up very well, but our tires are constantly leaving a very thin residue behind when we drive, hence balding tires. A single car doesn't leave much, but a busy road will quickly get covered, at least where the tires most often go, blocking the light to those tiles.

While I agree that grit and road grime are going to be an issue, I don't know if it's an issue of residue. I'm guessing the rubber lost from our tires ends up mixing with salt and sand and dust and washing away in rain.

What about frost heaves? Here in New Hampshire, the road heaves quite a bit during late winter. The road just kind of bends with the heaves, though there are also tons of cracks and holes that form. Can these panels bend the same way as asphalt?

Hexagonal tiles should handle that pretty well.

What about theft? If I go out and pry up a few panels, can I supplement my home electric? I imagine there would be some people more than happy to swipe a few tiles, stick them in their backyard, connect them up to their home, and get free energy. Currently, asphalt is theft-proof. It has no value outside of the road.

Yep, this is a problem.

Kharthulu
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Re: Solar Road Ways

Postby Kharthulu » Wed May 21, 2014 9:12 pm UTC

Theft is not a problem. Each hexagonal tile is connected to each other wirelessly. You'd literally be driving away with a tracking device in your car.

stoppedcaring
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Re: Solar Road Ways

Postby stoppedcaring » Wed May 21, 2014 9:27 pm UTC

Kharthulu wrote:Theft is not a problem. Each hexagonal tile is connected to each other wirelessly. You'd literally be driving away with a tracking device in your car.

Correction: Theft will not be a problem twice.

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Re: Solar Road Ways

Postby cphite » Wed May 21, 2014 9:43 pm UTC

Kharthulu wrote:I did a search on the forums looking for somebody already talking about this and since i didn't find it, i felt i should tell you guys about it.

There is a small starting company. Their intention is to make it possible to convert all the road ways in america into solar panels. They assert that these panels can withstand the weight of the heaviest trucks, and provide the traction required, and they are also equipped with LED lights which can be programmed for many things, and heated so that any snow that falls will melt, thus getting rid of the need for salting roads or using snowplows. They assert that if this was done, it would generate 3 times as much power as the united states currently uses. Which would eliminate the feed for fossil fuel driven energy production, and would facilitate a wholesale conversion to electric vehicles totally a 75% reduction in america's carbon footprint.

Here is their website: http://www.solarroadways.com/intro.shtml
And here is the video some crazy person made to make the sell on these things more fun: https://www.youtube.com/watch?v=qlTA3rnpgzU

Do with it what you will.


Some problems...

First off, roads get dirty very quickly. Rubber from your tires, dirt and dust, trash; I can't imagine even a thin layer of that being conductive to generating power from light. It has to deal with constant vibrations, and the constant changes in weight that comes with traffic, in addition to any severe impact that might come with an accident for example. It has to deal with heating and cooling day after day and from season to season.

Yes, I get that they're made up of individual hexagonal tiles, and that one can be replaced without tearing up the whole road; but that's actually part of the problem - not only do the tiles have to be strong enough to deal with all of that stuff above, but the joins between the tiles and the electrical connections ALSO need to be strong enough.

And if it snows, forget about it... they're claiming that they're heated and that that will take care of snow, but the reality is when you melt dirty snow you get slush - not water. And if it's still snowing, you get snow on top of slush, which is even worse - for driving, and for continuing to collect sunlight.

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Re: Solar Road Ways

Postby cphite » Wed May 21, 2014 9:47 pm UTC

Kharthulu wrote:Theft is not a problem. Each hexagonal tile is connected to each other wirelessly. You'd literally be driving away with a tracking device in your car.


Assuming of course that you cannot disable the wireless signal by removing whatever power supply there is, or by placing the tile into something that blocks the signal.

If these things are worth money and are removable, people will find ways to steal them.

stoppedcaring
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Re: Solar Road Ways

Postby stoppedcaring » Wed May 21, 2014 9:58 pm UTC

It's a neat idea. You would automatically know exactly how congested traffic was at any given point, meaning traffic could be re-routed to adjust for congestion. But the logistical hurdles seem massive.

If they want to use the existing right-of-way to generate electricity, they could always set up solar panels between the opposing lanes of limited-access highways. Though I suppose that space is sometimes reserved for future expansion.

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Re: Solar Road Ways

Postby billy joule » Thu May 22, 2014 12:41 am UTC

stoppedcaring wrote:I can second this. The cost of establishing new right-of-way easements to transport electricity from random areas to where it's needed is high. If the road IS the easement...well, there you go.


That applies if the transmission lines are under the road, underground transmission lines are not a great idea (lossy, hard to repair, not upgradeable, expensive) and aren't used often, under a roads even worse, imagine a fault during rush hour!
I don't think the intention is to replace roads with panels and replace an entire transmission grid.
I agree that grid connection is cost prohibitive, I did an internship at a power gen. company and many small dam projects were shelved because of it. This is partly why the solar road is a bad idea; it requires orders of magnitude more grid connections than regular power gen.

Kharthulu wrote:We can build solar panels our in the middle of no where, but the power would be more accessible and easier and less costly to transport if it was literally made in front of your house or business.

I think you're overestimating the power density of this scheme, I would guess a city will need power from all the roads in the surrounding XXX mile area. The generation-consumption distance is still high.

If the panels are spread thinly you'll need expensive and inefficient small inverters, distribution and transmission transformers and meters* spread thinly.
When the panels are in one place you can have fewer, larger more efficient inverters, one large, efficient transmission transformer and one grid connection.

Or individuals/businesses rooftops are a much better place to put them for a boat load of reasons.

*each individual contribution to the transmission and distribution grids must be metered.

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Re: Solar Road Ways

Postby jewish_scientist » Thu May 22, 2014 12:55 pm UTC

I think that putting the solar panels on highways near pre-established structures in the mid-west would be best idea.

Solar panels would have to deal with the day-night cycle, but not the extreme winter-summer cycle that Northern states have.

The panels would provide power to nearby structures (probably a lot of farms), lowering the energy loss due to transportation.

Unless the highway goes directly to a major city, there would be little traffic. That means less rubber residue and stress on the panels.

billy joule wrote:Is american that land poor that you need to tear up all your roads and lay really expensive solar panels?

Would you convert a local field into a solar farm, thereby destroying an ecosystem, in the name of saving the global environment?

In the event of a solar flare, our infrastructure will collapse. (http://science1.nasa.gov/science-news/s ... ceweather/) I do not know what happens to solar panels during a geomagnetic storm, but I would not want to drive on it. By converting only small sections of road into solar panels, the damage would be minimized.

A single rural house does not use that much electricity. Possible, the solar panels could provide all the electricity the house needs.

Only a couple (http://xkcd.com/1070/) of the states would be interested in the project. That means, hopefully, the company would deal with the state governments, as opposed to the federal government. If you live in America, you understand why this is an advantage.

The mid-western states have the nick-name of tornado alley (http://en.wikipedia.org/wiki/Tornado_Alley). However, tornadoes that rip up roads are not common (http://en.wikipedia.org/wiki/Tornado_in ... and_damage).
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Re: Solar Road Ways

Postby Kharthulu » Thu May 22, 2014 5:06 pm UTC

They're planning on doing driveways and parking lots before they do actual roads. Although i think one city is getting interested in implementing them.

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Re: Solar Road Ways

Postby billy joule » Thu May 22, 2014 9:48 pm UTC

jewish_scientist wrote:
billy joule wrote:Is american that land poor that you need to tear up all your roads and lay really expensive solar panels?

Would you convert a local field into a solar farm, thereby destroying an ecosystem, in the name of saving the global environment?

Yes.
Personally, I don't consider intensive farmed monocultures 'ecosystems' worth preserving.
With all the negative environmental effects of intensive farming and the reduction in non renewable energy required I'd say the net effect on the environment would be very positive.
Marginal land where production is only economically viable because of subsidies should be the first to convert.



A single rural house does not use that much electricity*. Possible, the solar panels could provide all the electricity the house needs.


Maybe on sunny days....

This raises some interesting points about reliance on solar:

http://www.forbes.com/sites/quora/2013/ ... lar-power/

*somewhat irrelevant sidenote: I would guess the power use per residence is much higher that city dwellings, rural dwellings are much larger and older ( and poorer insulation, less efficient heating, less likely to have piped gas etc).

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Re: Solar Road Ways

Postby gmalivuk » Fri May 23, 2014 2:00 am UTC

jewish_scientist wrote:Would you convert a local field into a solar farm, thereby destroying an ecosystem, in the name of saving the global environment?
Absolutely. Better that than destroy the same field to build a parking lot or some other type of power plant.

And you're also begging the question about ecosystem destruction. It's possible solar farms could be a boon to biodiversity. (As billy joule points out, monoculture farmland is not an ecosystem I'm particularly concerned about "protecting", anyway.)
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Re: Solar Road Ways

Postby cjameshuff » Sat May 24, 2014 1:37 pm UTC

It's an absurd waste of solar panels. First you put them flat on the ground, through shading trees and buildings, rather than angle them toward the sun in an open area, then you put a thick layer of glass formulated for strength and durability over any optical properties over them, then you texture the surface of that glass for traction and glare reduction, then you cover the glass with dust, machine grime, leaves, snow (the heated roads suggestion is idiotic, there's nowhere near enough power for it), etc...

Every square meter of solar panel put into these things would likely be several times more productive located elsewhere. Just putting fixed-angle panels above the road would greatly increase their output, while also being a much more practical way of keeping snow off the road. Be a lot more accessible for maintenance and easier to wire up in the first place, too.

As for distribution, the very low power density that results, and the very low reliability of that power generation, means that you'll be laying down enormous amounts of conductor that won't be used anywhere near its capacity. And every tile will have to have power switching and monitoring capability to allow routing around damage which will be similarly underutilized, adding to the cost and losses.

Now, drop the whole "power the nation with solar roads" idea, and it becomes much more interesting. The tiles become just road tiles, with no compromises for putting solar panels and power transmission underneath, though they might still incorporate structures for cable runs, drainage, etc. They could feasibly be made much more durable than asphalt, reducing cost in the long term. It's not an idea without precedent, it'd just be a high tech brick road. It's just packing them full of solar panels and electronics that would be gratuitously inefficient and impractical.

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Re: Solar Road Ways

Postby Kharthulu » Sat May 24, 2014 2:35 pm UTC

They tested the efficacy of the panels covered in dust and noticed only a 11% decrease in power absorption. And think about how much of america's roads are not obscured by buildings. Or how many sky scrapers reflect light between them shining light down onto the streets.

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Re: Solar Road Ways

Postby gmalivuk » Sun May 25, 2014 12:23 am UTC

Have you ever actually been on a street lined by skyscrapers? Sure, it's still pretty bright to the naked eye due to reflected light, but it can also seem pretty bright in a well-lit room, yet anyone who's ever taken pictures in one knows the actual light level is far lower than in direct sunlight.
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Re: Solar Road Ways

Postby billy joule » Sun May 25, 2014 3:25 am UTC

Kharthulu wrote:They tested the efficacy of the panels covered in dust and noticed only a 11% decrease in power absorption.


How i interpret that:

"Our baseline efficiency is so much worse than regular panels that dust has little effect!"

It's like claiming the gas mileage of a Hummer only reduces by 11% when towing a 2 tonnes load, sure it may be true but it's not saying anything about the most important bit, that the baseline mileage of a Hummer is terrible..

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Re: Solar Road Ways

Postby cjameshuff » Sun May 25, 2014 6:28 pm UTC

Kharthulu wrote:They tested the efficacy of the panels covered in dust and noticed only a 11% decrease in power absorption.


That is a ridiculous claim to begin with (all that number means is that they tested it with enough dust to block 11%, which means nothing...you could get any figure you want by just applying the right amount of dust), and you ignore all the other reasons it's a bad idea.


Kharthulu wrote:And think about how much of america's roads are not obscured by buildings. Or how many sky scrapers reflect light between them shining light down onto the streets.


So? A large portion of roads are shaded by buildings, trees, etc. And at best only a small fraction of sunlight will be reflected from windows onto the cells. Indirect sky light or light reflected from windows will be so weak in comparison to direct sunlight that panels in such locations will produce essentially no power.

Even for open, unshaded, lightly traveled roads, for every panel put into this project, you can expect to lose around 30% due to the bad sun angle (dependent on latitude), likely around 50% due to the textured surface and thick glass, and another 50% due to dust, grime, and debris (which has a disproportionate effect because partially shaded cells suffer greatly in efficiency). Then there's the issues with location, such as weather and day length, and the inefficiency of having a huge network of power converters working with tiny trickles of power. We're not talking minor inefficiencies here: put the same panel somewhere else, oriented to catch the sunlight better, not even with a motorized mounting, and you'll easily get 5-10 times as much power out of it, and it'll be cheaper to install and maintain. Under the roads is just a stupid place to put solar panels.

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Re: Solar Road Ways

Postby Kharthulu » Sun May 25, 2014 8:47 pm UTC

Yay. They're funded. Now they can build a parking lot and get more practical data on the premise.

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Re: Solar Road Ways

Postby gmalivuk » Sun May 25, 2014 9:18 pm UTC

Cue fading into complete obscurity as the idea doesn't pan out and we never hear about them again.
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Re: Solar Road Ways

Postby cjameshuff » Sun May 25, 2014 9:56 pm UTC

gmalivuk wrote:Cue fading into complete obscurity as the idea doesn't pan out and we never hear about them again.


A bit of a shame, since the modular tiles approach to roads actually has some potential advantages. Simple dumb glass or ceramic tiles that can be cut to fit, easily pulled and replaced, allow drainage and cable runs through/underneath, are immune to pothole formation (of particular interest to me after what this last winter did to the roads)...even under-road markings and signal lighting might have some real uses. It's largely the whole solar thing that takes a good idea and makes it terrible.

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Re: Solar Road Ways

Postby Minerva » Mon May 26, 2014 2:55 pm UTC

Well, it's an IndieGoGo project, alongside many other brilliant examples of careful engineering on IndieGoGo such as "Mayan Quantum Energy Pyramid" and "Home Quantum Energy Generator". (Yes, that's seriously perpetual motion free energy machine on IndieGoGo, complete with obligatory photo of Tesla and everything. IndieGoGo does nothing to screen or stop such projects. Fully funded.)

Solar Roadways seems to be yet another crowdfunding project with lots of concept art, big promises, no engineering or technical substance.

Currently, the full size hexagons are 36-watt solar panels, with 69-percent surface coverage by solar cells.


A typical solar cell is about 20% efficient, and power figures are typically quoted under perfect laboratory conditions, on the equator at noon on a cloudless day at latitude tilt towards the Sun riding on a spherical frictionless cow in a vacuum, with a solar radiation flux of 1000W/m2 of sunlight with a certain standard spectrum hitting the solar panel.

So, under perfect optimal conditions you get about 200W/m2. They say 36W, so their panels must be about 0.18 m2, or about 0.26 m2 for each hexagonal cell with a 69% solar cell coverage factor.
That means the side length of each hexagonal cell should be about 32cm, which is roughly consistent with the concept art I think.

With each hexagonal cell having a power output (nameplate capacity) of 36W, you'll need 11.1 million of them to equal 400MW of power capacity, which is the same as a moderately small power plant, smaller than a typical coal or nuclear power plant. And if each cell costs $100 (just a made up number, really) that will cost 1.11 billion dollars.

We tested the heaters over the winter with a DC power supply that provided them with 72-watts. This was an overkill and made the surface warm to the touch on most winter days. We still need to experiment with different voltages at different temperatures, to determine the minimum amount of power required to keep the surface above freezing. Remember, they don't have to heat up to 85 degrees like the defroster wire in the windows of your car: they only have to keep the surface warm enough to prevent snow/ice accumulation (35 degrees?).


Well, world energy crisis solved! We've invented a revolutionary new energy generation gadget with a power output of -36W. :P

Originally, we were designing toward 80,000 pounds. That was supposed to be the maximum legal limit for a semi-truck. However, we live in logging country and a former logging truck driver informed us that they don't have scales in the woods and that he'd topped out at 124,000 pounds. So we decided that we should go for 150,000 pounds. We then learned that oil companies can get permission to move refinery equipment up to 230,000 pounds on frozen roads, so we decided to shoot for 250,000 pounds.


Obviously the load doesn't just depend on vehicle mass, it's pressure - which depends on the contact area that weight is distributed across.
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Re: Solar Road Ways

Postby gmalivuk » Mon May 26, 2014 3:09 pm UTC

Thanks to the wonders of ineptly necroing 6-year-old threads, I recently discovered that this bad idea has been around for a while. The recent uptick in awareness comes from the IndieGoGo campaign, but those comments from 2008 (along with another set from the first necroing in 2010) suggest that they still really haven't addressed most of the basic issues people were already having with the technology back then.

Edit: actually it turns out that they first put up an ugly website at least as far back as 2006. Note that my Firefox didn't seem to like the archived page, and slowed to a crawl for some reason, so click at your own risk.
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Re: Solar Road Ways

Postby cjameshuff » Mon May 26, 2014 4:13 pm UTC

20% is actually a fairly good solar cell. Fairly good == fairly expensive. Cheap thin-film and amorphous cells will be around half to a third of that. I wouldn't be surprised if they're using expensive high-efficiency cells for their prototypes, though...cells expensive enough that it's often considered worthwhile to put them on motorized mounts to keep them facing the sun.

The higher the efficiency of the cell, the more you lose by not putting it somewhere better suited to collecting sunlight. For higher efficiency, higher cost cells, the cost of the land and associated machinery for more optimum placement is less significant. Where's the motivation for stuffing them under the roads?

Also, you can't just connect photovoltaic cells together in huge arrays. Simple manufacturing variations mean that some will produce more poorly, and will actually load down other cells connected in parallel with them (large single cells have a similar issue with manufacturing variations across the cell surface). The same happens if one cell is shaded even partially, a large amount of power is lost if an array (or a single very large area cell) isn't evenly lit. There's also failures: a short circuit in one will short out others connected in parallel, and open-circuit those connected in series. And there's safety, you'll need a way to shut down power to an area for working on it.

So each tile is going to need a power converter. The thing is, power conversion benefits from large scales and spending reasonable amounts of money on hardware. For this, you'll need a tiny 36W power converter for every tile. Roughly the equivalent of a wall-wart in every tile. Consider the failure rate if cheap power converters with the build quality of typical wall-warts are stuffed under the roads where they're exposed to vibration and extremes of temperature. Consider the conversion losses...cheap, small power converters are generally around 60-80% efficiency. Consider the cost of equipping every little tile with a high reliability, high temperature range, high efficiency power converter, each pushing out a maximum of 36 W (for a road on a sun-facing slope for a brief period around noon). Consider the fact that the vast majority of these power converters aren't going to be operated anywhere near their rated capacity...there's a huge amount of capacity there being manufactured, bought, installed, and wasted. How very "green".

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Re: Solar Road Ways

Postby Minerva » Tue May 27, 2014 2:29 am UTC

Also, if you've got a road covered with snow and ice, the snow and ice doesn't absorb enough solar radiation to melt it, let alone allow the solar radiation to be transmitted through the snow and ice to reach a solar cell which converts the light to electricity with substantial inefficiency which powers a heating element to melt the snow and ice. That aspect of what they're claiming is ridiculous.
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Re: Solar Road Ways

Postby Magnanimous » Tue May 27, 2014 7:35 am UTC

If we're going to be harvesting energy from roads, piezoelectric generators might be a more practical option. In cities and high traffic areas there's plenty of energy being lost as vibrations/heat. This paper from last year mentions the floor in a Tokyo metro station that generates electricity from high foot traffic, and putting compressive material under roads shouldn't be much different.

Although from what I understand that would probably have lower wattage output than solar panels, and transporting the electricity is still be a problem. Most of that paper's examples were fairly local, like shoes that charge your cell phone when you walk...

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Re: Solar Road Ways

Postby speising » Tue May 27, 2014 8:57 am UTC

doesn't piezoelectricity just steal energy from everyone walking or driving over the floor? i imagine it increases energy expenditure.

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Re: Solar Road Ways

Postby cjameshuff » Tue May 27, 2014 11:14 am UTC

speising wrote:doesn't piezoelectricity just steal energy from everyone walking or driving over the floor? i imagine it increases energy expenditure.


Right. You'd just be using inefficient, pollution-generating car engines to produce electrical power, and via a rather inefficient mechanism and maintenance-heavy approach at that.

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Re: Solar Road Ways

Postby gmalivuk » Tue May 27, 2014 11:49 am UTC

That doesn't have to be the case, though, since as mentioned the energy that goes into noise and vibration is wasted to begin with.

Minerva wrote:Also, if you've got a road covered with snow and ice, the snow and ice doesn't absorb enough solar radiation to melt it, let alone allow the solar radiation to be transmitted through the snow and ice to reach a solar cell which converts the light to electricity with substantial inefficiency which powers a heating element to melt the snow and ice. That aspect of what they're claiming is ridiculous.

Snow doesn't melt because it reflects most of the sunlight, not because there's too little sunlight to begin with.
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Re: Solar Road Ways

Postby cjameshuff » Tue May 27, 2014 12:03 pm UTC

gmalivuk wrote:That doesn't have to be the case, though, since as mentioned the energy that goes into noise and vibration is wasted to begin with.


These actually account for an extremely small fraction of losses (consider how loud a kilowatt of noise and vibration would actually be), and selectively collecting them would be quite difficult. Just putting compressive piezoelectrics under roads would add rolling resistance and decrease the efficiency of every car on the road (including electric vehicles).


gmalivuk wrote:Snow doesn't melt because it reflects most of the sunlight, not because there's too little sunlight to begin with.


Right. While inefficient, solar cells would allow collection of energy from uncovered areas to melt covered areas from underneath. They might be better off with something that just spreads heat via conduction...

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Re: Solar Road Ways

Postby gmalivuk » Tue May 27, 2014 12:21 pm UTC

No one expects kilowatts from piezoelectric generators, and they could be used in cities where rolling resistance isn't as big a part of the energy the car exerts.
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Re: Solar Road Ways

Postby speising » Tue May 27, 2014 1:38 pm UTC

except that one goal of surfacing material design is to reduce resistance and noise.

btw, t can't imagine a road made of hexagonal tiles to provide for a very smooth ride. one of the advantages of asphalt is its viscosity which helps to smooth small irregularities. the tiles, otoh, would tend to get out of perfect alignment.

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Re: Solar Road Ways

Postby Whizbang » Tue May 27, 2014 1:56 pm UTC

Also, plows would tear those things up. I know that where I live, if a plow passes through, it is a sure bet the blade will get caught on a crack or something that was sticking up and just tear out a new pot hole. I am imagining snowbanks just loaded with road tiles.

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Re: Solar Road Ways

Postby cjameshuff » Tue May 27, 2014 3:58 pm UTC

gmalivuk wrote:No one expects kilowatts from piezoelectric generators,


Which was my point. They wouldn't be worth installing.


gmalivuk wrote:and they could be used in cities where rolling resistance isn't as big a part of the energy the car exerts.


Cities, with their traffic density and existing pollution problems, are precisely where you most want to avoid decreasing the efficiency of cars.

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Re: Solar Road Ways

Postby cjameshuff » Tue May 27, 2014 4:08 pm UTC

speising wrote:except that one goal of surfacing material design is to reduce resistance and noise.


And their textured surface turns out to be a grid of large bumps which looks like it'd be quite noisy.


speising wrote:btw, t can't imagine a road made of hexagonal tiles to provide for a very smooth ride. one of the advantages of asphalt is its viscosity which helps to smooth small irregularities. the tiles, otoh, would tend to get out of perfect alignment.


My original thought was that these would be high-tech cobblestone roads, with thick tiles that could interlock with their neighbors to distribute loads to the bed underneath and ensure a reasonably smooth surface as long as they have a halfway acceptable foundation. It actually turns out they're just a thin cover bolted to a concrete road.

There's some more discussion here, with someone who claims to be "a member of the Solar Roadways Support Team" spouting babble about neural networks and such while evading technical questions:
http://arstechnica.com/civis/viewtopic. ... &t=1244911


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