EEVblog #632 - Solar Roadways Are BULLSHIT!

[DJ]

This is sadly not uncommon,  our (broke) government knows only how to spend money. Frequently for idiotic programs, and always so politicians and bureaucrats can keep their jobs.

As for this debacle,  one hardly knows where to start.

As for the msee, not seeing anything spectacular in the c.v.

http://www.linkedin.com/pub/scott-brusaw/2a/84/72a

Still, anyone is capable of the quintessential better mousetrap.

The guy was schooled, working in ohio, which from a solar perspective is bad. His digs in northern Idaho aren't much better



LED visibility would require something on the surface for any hope of lateral dispersion. 3M scotchlite glass beads or the like perhaps. That would wreck transmissivity to the solar cell.

Surface friction of glass would be horrendous.  Like having ice on the road year-round.

Salt, sand, cinders, chains and studs are used for traction enhancement on normal roads. Maybe suction cups would work...

Tractor tire loadings? Seriously? 

Heating glass roadways? On an infinite heat sink? Does the University of Dayton offer heat transfer/thermo?



On the plus side, he's raking it in.

maybe I will launch magnetic roadways, which will generate free energy from cars with steel belted radial tires.

[mux]

So pretty close to my estimated 30kW.
These numbers have to be hand-wavey, because real data doesn't exist for the very small view angles and thick glass we are talking about here.
It needs serious empirical measurement.

My complaint is with the method used; using watt-figures for LEDs and using spacing for LEDs as a guideline instead of using actual visibility metrics (which is perfectly possible in this case!)

I get what you are saying, but I'm not convinced your numbers are any better, or that you are comparing apples with apples here.

I'm not declaring my numbers holy, just saying that the method is a bit more credible/backed up by a reasonable method to get there than just saying that one LED uses 0.5W.

Where did your nighttime consumption go?

Same way that the nighttime sun went. Away. You run the LEDs proportional to the sunlight. At night, typical lights only need to produce in the order of tens of lux to get reasonable visibility. Existing road markings do nothing other than just reflect that light, whereas the asphalt absorbs it, creating a contrast. With the LEDs, you do the same. I did nothing other than apply the insolation formula to the LED lights.

I'm not discussing the numbers here with you, I'm discussing the method. In your video you didn't display any kind of research or method to your calculations, so the calculations simply don't make sense. The LED calculation I did here is just an example of one calculation that can be done much better, but that goes just as much for your other arguments: there are good ways to do proper back of the envelope engineering here, and I am of the opinion that you were just entirely handwavy, no method at all. That really doesn't help a discussion that tries to debunk something like this. You need to have strong arguments, backed up by credible calculations. If you're just trying to get your opinion out there you shouldn't do these messy calculations.

[DJ]

Even Forbes raised an eyebrow

http://www.forbes.com/sites/quora/2014/06/05/could-solar-panels-replace-concrete-or-asphalt-roads/

Let's not forget that you still need the subroadbed for mechanical support. Now we need to match coefficients of expansion.

Also, roadways are not flat. They are crowned for drainage. Do we have to grout all these solar tiles?

Asphalt & concrete are generally priced in different units, but for comparison only (residential)

http://www.teamelmers.com/driveways-2


Have we talked about oil buildup? On glass-yikes. On plastic-clouding.


Years back, our state DOT tried Superpave. Miracle mix. Supposed to last decades. Failed in under a year. Had to be torn up. Taxpayers hosed again. This is a cluster. This is .gov giving money away to fix things that aren't broke. No. Just no.



ETA: the superpave debacle. They fired one of the engineers for publicly admitting it sucked.

http://old.post-gazette.com/transportation/20030216gratacol0216p4.asp

[zapta]

Video will be back up after I fix the edit and re-upload tomorrow morning, maybe by 10am.
Yes, I really rushed this one. A rare one where SWMBO let me stay back to finish and upload it.
FAIL.

Reminds me the funny glitch at 0:10 here ;-)   



(please don't 'fix' it).

[Legit-Design]

We have two types of surfaces:
1) a semi-smooth walking surface that is capable of stopping a car going 40-mph on a wet surface in the required distance
2) The one you see in the video with the raised hexagons was designed for highway use and can stop a car going 80-mph on a wet surface.

We talked with the civil engineers who conducted the traction testing and they've assured us that the testing covers trucks, cars, motorcycles, and bicycles. So if you don't slip on asphalt or concrete, then you won't slip on our glass.

Hmm they are saying a car can stop on their surfaces from certain speeds. What is the required distance?

But since they are also saying the roads will pay for themselves:

How long will these Solar Road Panels last?

We're designing our panels to last a minimum of 20 years. Solar cells are the limiting factor: they can continue to work up to 30 years but they're at the end of their life cycle by then.

So I guess we could assume their panels will pay for themselves on that minimum 20 years life expectancy? That is a very long time for return of investment? If some panels last 30 years and some only 20 years it will all be balanced out?

Are they actually claiming the panels will start to spew out pure profit after what time? NO. They are just saying we got contract to design a surface that will pay for itself during it's lifetime. But since it's solar everyone naturally assumes their roads will start to spew up profit after certain period like all solar power systems? Ok since we aren't already being told the whole truth maybe this could slide also? Like with everything there is always a way to make numbers more favorable. I think I might get some of their thinking. If we just take that the lifetime of the product is the same as the return of the investment? And they counting on the road being always perfect and only fraction of percent of roads need to be replaced during their lifetime. If they just told the truth like it is, not many people would be that interested I guess?

[Tronicgr]

http://www.nbcnews.com/business/business-news/growing-copper-theft-epidemic-sweeping-us-f6C10791941


I can only imagine what will happen to these really expensive solar tiles after a while, unless they have a way to superglue them on the road 




Thanos

[EEVblog]

BTW, their website has a ridiculous 'Clearing the Freakin' Air' page where they try to "bust" some myths surrounding their product -- without including a SINGLE piece of data ANYWHERE on the page.

Yup, it's almost comical, as is most of the stuff on their website.

[EEVblog]

Any rough numbers for the price of the glass (per square meter) they would need?

I've done some basic research on this, and it seems that $10/sqm is probably in the ballpark for suitable 16mm stuff in volume.
But they need the bumps and the roughening etc.

[EEVblog]

I'm not declaring my numbers holy, just saying that the method is a bit more credible/backed up by a reasonable method to get there than just saying that one LED uses 0.5W.

I won't argue that. But the fact that my research showed about 0.5W to be an average LED sign brightness over the course of the day (assuming it's even visible), that was backed up by your numbers (also rough and unproven in this exact scenario) showed that we both likely aren't far off.

Same way that the nighttime sun went. Away. You run the LEDs proportional to the sunlight. At night, typical lights only need to produce in the order of tens of lux to get reasonable visibility. Existing road markings do nothing other than just reflect that light, whereas the asphalt absorbs it, creating a contrast. With the LEDs, you do the same. I did nothing other than apply the insolation formula to the LED lights.

And I think this is likely wrong.
You aren't taking into account the massively shallow angle, well outside the operational angle of the LED's.
And you you aren't taking into account the headlights.

If you're just trying to get your opinion out there you shouldn't do these messy calculations.

I disagree.
I think it's a good ballpark calculation. Seems to be more than Solar Roadways have done, at least publicly.
I admit the LED consumption will have a lot of variability, but it shows that the LED consumption matters. Even if the LEDs consumed nothing at all all day, the generation numbers still suck.

[Mr Simpleton]

I'm pretty confident that it will keep the streets snow free at Daves place, but here in Sweden I measure about 200W/m2 at noon during clear sunny winter days, and peaking 1000-1100 W/m2 now in late june. Not sure how many watts will be left after the snows been falling all night and freezing up too.

[AlfBaz]

How far apart are these "raised hexagons"?

The surface area of a typical tyre contacting the road would be no more than 100 x 100mm (4x4"). The instant a braking tire hits a smooth section it will skid and hitting another "raised hexagon" an instant later will do nothing to overcome the force required to allow the disc to break free from the brake callipers.

As for environmental cred, even if this system worked at 110% efficiency, how many years would it take to recoup the negative environmental effects of obtaining the raw materials, manufacturing the tiles and installing them?

KISS... Here's a seemingly far better "green" solution
http://www.sydneymedia.com.au/taking-the-light-road-to-a-cooler-future/

[EEVblog]

From their FAQ http://www.solarroadways.com/faq.shtml#faqBikes

What about motorcycles and bicycles? Won't they slip on the glass surface? What about strollers, skates, skateboards, wheelchairs, etc.?
We have two types of surfaces:
1) a semi-smooth walking surface that is capable of stopping a car going 40-mph on a wet surface in the required distance
2) The one you see in the video with the raised hexagons was designed for highway use and can stop a car going 80-mph on a wet surface.

And they have tested that, how exactly?
Where is the video?
After 5 years of working on this and $850K, you'd think that'd be the first thing you test and demonstrate in a real scenario.
But no, they have gone walkabout and developed all the electronics and associated tech, without showing so much a single test run on the proposed surface.
#1 requirement is that this be a suitable road surface.

[KD0CAC John]

Here in Minnesota U.S. where we have snow & ice , we use to have studs in our tires .
I think get a bag of them and install on my tires when these show up .
 

[DJ]

Here in Minnesota U.S. where we have snow & ice , we use to have studs in our tires .
I think get a bag of them and install on my tires when these show up .

Solar roads will not be implemented in Minnesoota until the glaciers recede.

if global warming kicks into high gear, that could happen as soon as 2095.




(whole new perspective on foot-pounds...)

[KD0CAC John]

I like the warmth between ice ages

[DJ]

I like the warmth between ice ages

You guys rock

Don't know how you do it. Had a client north of Sioux Falls,  went up there one January.  -13F @ noon. -51F with windchill. Full heat on the rental car,  and still froze my butt.

[Jay_Diddy_B]

Hi,

The would show it working, but they are waiting on delivery of their Mu Optics Thermal Camera 

Jay_Diddy_B

[miguelvp]

The video shows here as private

Nevermind, read the thread I'll wait until tomorrow

Edit: lets see their solar roadways melt this mess (Chicago this past winter)

[EEVblog]

Ok, replacement video has been uploaded. Fixed the video editing issues, and added a bit of extra stuff on LED consumption and payback calculations.
Sorry to all those who commented on youtube for the previous video, I can't transfer those comments over to the new video.

[SeanB]

Just adding in 5c about loading with a tractor, that is designed to spread the mass of it and the load out over a very broad area using the tyre patch. You can drive that JD over mud without it bogging down and digging a furrow, but try doing that with a legal 22m long superlink with 8 axles and a legal maximum all up load of 65 tons. There you will likely get 3 axle sets and nothing more off the hard paved roadway before it buries itself and stops axle deep.

Building sites have a big issue with trucks delivering building material especially just after they have laid a tar driveway, as the trucks easily either cut a furrow through the tar, or the driver dry steers and tears out divots of tar, and rolls them to another spot and sticks it down. Even a well cured tar surface will spread and furrow with heavy truck loads.

To use this you will need to have weighbridges on each entry to limit the allowable axle loads or else you wil break panels, no matter how thick. Even concrete roadways suffer from edge damage from heavy truck loads.

[gildasd]

Dave's magic marker toss at the very end of the video is a thing of beauty.

He's a consummate professional.

[DrGeoff]

Expensive dance floor for a nightclub?

[daqq]

The solution to this is simple - tilted roadways! Snow will be less likely to stay there, it'll just slide of gracefully, the efficiency will improve and everyone goes home happy! Also, make sure the glass is slippery, it'll repel the snow better!

[DrGeoff]

Let's see a D10 run over the roadway. Or a tank

[stenor]

I posted this in the comments:

Hmm. I was enthusiastic with this project first, thinking it was great that people where thinking environmentally and such. I’m not an engineer, but I felt alright with the concept, trusting what I do not know with the ones who supposedly do!

Well, It seems my judgement failed me this time. Look at this: www.eevblog.com

How can this be dis-proven?

Lets see if this will be allowed to stay...

Myself, I guess I was swayed by the government approval and funding etc... so my critical mind was kind of shut off. Though some part of me is hoping there's a method to the madness, and that the funds will go into a more serious type of engineering.
I mean, will they flee the country and live anonymously in some island somewhere? That certainly does not sound feasible to me.