Solar Roadways Project Beats $1M Goal, Should Enter Production

Lucas123 (935744) writes "It appears an Idaho-based company that created prototype panels for constructing roads that (among other features) gather solar power, will be going into production after it exceeded its crowdfunding goal of $1M. ... Solar Roadways' Indiegogo project has already exceeded $1.6 million. The hexagonal-shaped solar panels consist of four layers, including photovoltaic cells, LED lights, an electronic support structure (circuit board) and a base layer made of recyclable materials. The panels plug together to form circuits that can then use LED lights to create any number of traffic patterns, as well as issue lighted warnings for drivers. The panels also have the ability to melt snow and ice. Along with the crowdfunding money, Solar Roadways has received federal grant money for development."

Comments

Thermodynamically Impossible

[Cassini2]

Isn't it impossible for solar cells to melt significant snow?

The black road surface will effectively capture almost all of the sun's energy. In the northern U.S. and Canada, roads routinely get covered in snow.

The solar cell can capture a portion of the sun's incoming energy, and potentially use it to power heaters to melt the snow. This approach has several problems. Firstly, the solar cells / heater mechanism is less energy efficient than a black road surface. Secondly, if the snow falls when it is dark, the solar cell will stop working (unless it has some big batteries are present, and even they won't last long in a heavy snow fall.) Lastly, the best sun occurs in the summer, and the snow hits in the winter, when less solar energy is available.

About the only way a solar cell can keep up with incoming snow is if the solar array is much larger than the area of snow being melted. However, even then, you still have the problem of the solar array getting covered in snow ...

Re:Thermodynamically Impossible

[Maury Markowitz]

> Isn't it impossible for solar cells to melt significant snow?

Yes. Obviously if there is enough energy in the sunlight to melt the snow, the snow would melt already.

Heating snow to clear it is multiply-times less efficient than scraping it off with a snowplow.

This whole idea is the dumbest thing I've seen in years, designed by someone who knows nothing about solar power or road engineering. Ask anyone on the planet who's ever had a re-lay a cobblestone road surface how well they think this will work.

Re:Thermodynamically Impossible

[Anonymous Coward]

Seriously, cobblestone?

I'm a transportation engineer (I'm posting this anonymously so the details of my employment are not associated to my account) though with very little experience designing pavements. What my experience tells me though is that regardless of the panel itself it needs some sort of frame to hold it down.

Vehicles generate thousands of pounds of force parallel to the pavement face when they brake. This is what causes rippling in pavement at intersections when the asphalt is too soft or weak. So they've got the friction to stop the car what transfers that force to the ground (and prevents the ground from shifting)? Naturally you are going to need some sort of frame with very positive connection to the ground. That sounds unbelievably expensive. Current roadway costs are near $2 million dollars per lane mile (a 12 wide width of pavement 1 mile long). The materials that make up the roadway are generally pretty cheap (various engineered sands and gravels) and are applied to the roadway using large heavy equipment with very little human labor. You've now replaced that with presumably the same base system (you still have the same loads) a metal frame to hold the panel in place and the panel (these systems would replace the hard surface ie the asphalt or concrete). Even a minimal frame material wise is going to massively expensive. Steel is very very expensive in rough bar form (in comparison to things like concrete and asphalt), let alone in machined frames that require manual hand labor to install. What happens when a frame is bent? How's it anchored? Even massively damaged pavements are usually traversable, a missing or damaged panel sounds like a 2' circumference 1' deep pothole that will rip a tire off a vehicle at speed.

The next question is durability. They say they've tested them with truck loads, have they done the standard AASHTO pavement test that involves driving a semi around (in a 1/4 mile loop track) on them for 5 years straight to demonstrate long term durability? What about studded snow tires? What about an accident where a car flips at 70 mph and imparts forces that literally pulverize concrete to powder? What if the car then burns (a typical car fire approaches 3000 degrees) What about an accident where hazardous or corrosive products are spilled? What happens when a car being chased by the cops has it's tires shredded but then keeps driving on rims for 20 miles until the rims literally weld themselves to the rotor (the typical result on standard pavement is about a half inch groove from every rim for the length the car ran without rubber)? What about road debris coming off cars and hitting other cars (I've seen sections of concrete a foot thick destroyed by heavy objects falling off semis)?

How long are the panels good for? We design asphalt roads for 20 years and concrete for 40-50 years. And though the asphalt requires perodic treatments as part of it's life cycle unless a mistake was made they generally last that long. Most of the interstates lasted far longer than the 40 years they were designed for, in my state we've still got original interstate in locations that is approaching 60 years old.

We use the materials we do in roads because they are cheap, easy to put down (ie not labor intensive) and easy to fix (a temporary fix can involve dumping and spreading a load of gravel with common construction equipment). This system just screams money, and labor and lack of durability. Maybe I'll be wrong, I suspect I won't be. The ESALs (equivalent single axle loads) that a pavement takes over a life time can be astonishing (trillions of pounds of force over a 20-40 year lifetime). The panel and frame that support this are going to be flexed billions of times a year, fatigue fractures are a very real concern in metals.

Anyway, as I say I might end up wrong, i suspect I won't. I'm astonished people donated a million bucks for this and I believe once they do the real AASHTO testing that will be required before this can be used on roads they will demonstrate

Critical piece in The Verge

[De Lemming]

The Verge had a good article criticizing this project. The article doesn't break down the project completely, but points out why their goals are far-fetched, and people should not get too exited.

Also note that when looking at the project, it's not initially clear that a connection with the main electricity grid is still necessary. At night, displaying the signs and defrosting the road is done with electricity from the net. During the day, the solar panels can transfer electricity back to the grid. Their current implementation doesn't include batteries to store electricity locally, and this wouldn't be very environmentally friendly anyway.

Re:Deja vu

[nysus]

That is, in fact, their plan.

Read about it on the "Vision" page of their website: http://www.solarroadways.com/v...

Re:Deja vu

[nysus]

They address this on their website:

"What are you going to do about traction? What's going to happen to the surface of the Solar Roadways when it rains>

Everyone naturally pictures sliding out of control on a smooth piece of wet glass! Actually, one of our many technical specs is that it be textured to the point that it provides at least the traction that current asphalt roads offer - even in the rain. We hesitate to even call it glass, as it is far from a traditional window pane, but glass is what it is, so glass is what we must call it.

We sent samples of textured glass to a university civil engineering lab for traction testing. We started off being able to stop a car going 40 mph on a wet surface in the required distance. We designed a more and more aggressive surface pattern until we got a call form the lab one day: we'd torn the boot off of the British Pendulum Testing apparatus! We backed off a little and ended up with a texture that can stop a vehicle going 80 mph in the required distance."

Not sure how true or relevant this is but they do address it.

Re:Deja vu

[MrNaz]

You missed the whole point of durability that I mentioned.

In Thailand, many of the roads in the southern areas use glass balls as lane markers. They don't get driven over unless a wheel is in on the lane marker, hence, only a small fraction of the actual traffic. Nonetheless, it is plainly obvious that they just don't last. They are chipped and damaged to the point that they don't fulfill their function.

Roads are possibly the most abused surface mankind makes. No type of glass that we have access to could ever stand up to long term road wear. It's just not possible with today's tech. I really think that this is a grant scam, which is unfortunate, because the politicians being scammed will be less favourable to green projects the next time a real idea comes around.

Re:Deja vu

[nysus]

Sorry, I was scrolling up and down the page, got distracted, and copied the answer from the wrong question. Here's what they say:

"How will you replace damaged panels in a highway?

Since our system is modular, repair will be much quicker and easier than our current maintenance system for asphalt roads. We've learned that in the U.S., over $160 billion is lost each year in lost productivity from people sitting in traffic due to road maintenance.

Each of the panels contain their own microprocessor, which communicates wireless with surrounding panels. If one of them should become damaged and stop communicating, then the rest of the panels can report the problem. For instance, "I-95 mile marker 114.3 northbound lane, third panel in, panel number A013C419 not responding".

Each panel assembly weighs 110-pounds. A single operator could load a good panel into his/her truck and respond to the scene. The panel could be swapped out and reprogrammed in a few minutes. The damaged panel would then be returned to a repair center. Think of how this compares to pot hole repair!"