Slashdot Mirror
Solar Roadways Get DoT Funding
mikee805 writes "Solar Roadways, a project to replace over 25,000 square miles of road in the US with solar panels you can drive on, just received $100,000 in funding from the Department of Transportation for the first 12ft-by-12ft prototype panel. Each panel consists of three layers: a base layer with data and power cables running through it, an electronics layer with an array of LEDs, solar collectors and capacitors, and finally the glass road surface. With data and power cables, the solar roadway has the potential to replace some of our aging infrastructure. With only 15% efficiency, 25,000 square miles of solar roadways could produce three times what the US uses annually in energy. The building costs are estimated to be competitive with traditional roads, and the solar roads would heat themselves in the winter to keep snow from accumulating."
I'm sure they did fairly decent testing with 4 wheel vehicles, but my motorcycle lacks the inherent stability that a car has. How bad would a surface like this be when it gets wet?
My sausage tree didn't grow, does that make me a bad mommy?
How will the oil drippings and the tire residue affect the panel output?
So much for the solar panels when a 4 ton 4WD EMT truck rolls along on at 40mph.
RS
Shoes for Industry. Shoes for the Dead.
For heavily used surfaces it probably wouldn't work.
Most shoulders (in Canada) are paved and very lightly used. Most of the streets in neighbourhoods are also very lightly used (hundreds of slow moving cars per day and not tens of thousands).
I imagine there are locations where this could be used as a surface that is durable enough. The big question mark is production cost (more expensive than current surfacing for a 50 year period) and does it generate enough to make it worth wiring it into the grid.
The test seems very cheap. Surfacing tests of different asphalt mixtures on the order of millions are regularly done.
Rod Taylor
One other problem with concrete is that at the "seams" (not to mention the cracks) between panels water can get through to the ground underneath. This can lead to localized soil expansion/contraction which causes stress on the concrete and accelerates the deterioration. If a lot of water gets through the ground can be unstable enough to allow the panels to "rock" then they don't line up evenly any more. I would think these large glass panels could be susceptible to the same problem.
My old sig was REALLY stoopid.
able to leap tall buildings and being bullet proof...
I am not overly worried about its resilience, I am more worried about how the surface drains water and traction on when wet. Being an avid motorcyclist I dread new roadway compounds because half the time they forget that two wheelers exist. Rubber directional signs applied to road surfaces are already not friendly, I don't need more.
* Winners compare their achievements to their goals, losers compare theirs to that of others.
Maybe we should call it "Snake Ethanol".
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
A much more effective concept is solar roofs. Rather than putting panels on top of roofs, the panels are the roof. This has many advantages. Rather than paying for a roof and solar panels, plus the headaches of attaching panels to a roof, you only pay for one surface. Mounting roof panels to rafters is easier than mounting panels to existing roofs. The wiring is on the inside, where it's in a dry space. The panels behave better in high winds, since winds can't get under them. And you can mix solar panels and plain roof panels, using solar panels only on the surfaces pitched to get the most sun.
Roads are a much tougher environment than roofs.
You should also beware applying your experience with solar cells to to every solar cell. I would probably be willing to put money of the fact that you were working with monocrystalline cells. Yes using monocrystalline cells in this situation would be stupid. But to be honest the people designing these project did not even consider monocrystalline because their advantages/disadvantages do not match this project at all. Amorphous cells on the other hand match the job a lot better. Cheaper more rugged and relying more on large surface area than high efficiency.
I was going to say, how many accidents would this cause?? If you made the surface with a friction, it would reduce it's ability to absorb light. If you avoided that, you'd have cars that are unstable. I get nervous crossing metal grated bridges. My car sways as it grabs traction on the not quite straight lines in the road. What's going to happen when it becomes impossible to stop, accelerate, or turn (lane change). It's a pending disaster. A little rain, and it's a disaster for safe driving. I will admit, I've done emergency lane changes, because someone did something stupid in front of me. With this plan, emergency lane changes would become impossible, right along with braking.
I'm sure they tested with cars. What happens when you constantly run one over with fully loaded 53' trailers? It's obvious where trucks frequent an area, the ditches created by their weight, even in asphault, would destroy the panels.
But hey, not my idea, and I'm not responsible for the liability involved. We'd be better off using the right of ways (that pesky grassy area on either side of the road) for solar, and they'd be able to track the sun for improved light absorption.
Serious? Seriousness is well above my pay grade.
The problem is that you need about 30,000 square miles of solar panels, at current efficiencies of about 14%, to solve the problem. There are apparently only about 500,000 acres of rooftop. If these guys shoot for "solar roadway" and miss by a fair bit, they might wind up with "solar parking lot", which would solve a bigger chunk of the problem than "solar rooftops" could.
If you mod me down, I shall become more powerful than you could possibly imagine.
People should really read the FAQ and the numbers.
To sum up: it's significantly more expensive, but since glass doesn't wear like asphalt does (it either works or breaks -- and it doesn't generally break from compressive stress, only torsional stress and impact), it should last longer and need less maintenance. And since you also get power out of it, displace plow crews, etc, they make the argument that it'll be a better investment if they can make the panels for $10k or less each.
Given that the one-off prototype is to cost $100k, and they have the potential for a *huge* amount of mass production, I don't think it's all that unrealistic. I'd still like to see how they handle in the real world, of course, but hey, that's why you give funding to build prototypes. ;)
Oh... yes! The numbers! I love the wishful naive thinking on that page, it's just brilliant.
For example, lets examine one of the pieces of insanity on his site. He mentions embedding supercapacitors into the road surface to store energy (I assume overnight). If you don't know what those things are, they would be the filthy expensive, highly experimental, rarely used in commercial products devices with lower than battery storage capacity. I'm sure they'll improve, but I can come up with fancy plans too if I can have parts made of unobtanium.
I particularly like the plan to use the ultracaps to store sufficient power to melt ice off the roads. The inventor clearly doesn't remember his 1st year Physics, where we learnt that the the enthalpy of fusion of water is surprisingly high compared to most other chemicals.
Ok, lets get practical: I'm basing this off the technical specs (PDF) for one of the beefier ultracapacitors made by one of the top companies in the biz - Maxwell Technologies. (note: I'm sure better devices are available from somewhere else, will be soon, etc.. bear with me)
It states that a device that is about 17.6cm high and has an area of 18.9cm x 51.5cm has a total capacity of 55Wh (~200kJ). That's a big capacitor.
So if you made a road surface with it, every 973.35 cm^2 area would have 200kJ of stored power for it. That's about 200J per cm^2.
Since the enthalpy of fusion of water 333 J/g, then 200J of energy will melt 0.6g of water. A layer of water (or ice) 0.6g/cm^2 is 6mm deep.
To summarize, this guy's fancy 'invention', if 100% efficient could melt 6mm of ice (or something like 5cm of snow), assuming that the weak winter sunlight was sufficient to fully charge the capacitors during the previous day. That's assuming the entire road surface has a layer of supercapacitors in it 17.6cm thick (that's 7 inches for you yanks).
Even if you gave the benefit of doubt and assumed a 10x improvement in supercapacitor technology, you still have to factor in that he plans to use the solar power capacity for other things too, like lighting up the LED arrays built-in to the road, and to power nearby homes. Not to mention that no matter how much capacity you have, there's not enough sunlight to charge it.
Note that the cost estimates conveniently left out the cost of the ultracaps. On one of the pages, he mentions a target price of USD48 per square foot. The Maxwell ultracap is about 1 square foot, so we're looking at $48 split between a square foot of: Solar cells, the glass coating, an ultrapacitor 7 inches thick, high intensity LEDs, heating coils, power management electronics, the road substrate, and more.
Who was the moron who gave him $100K? Can I have my free money now too? I can come up with all sorts of wild plans also that make zero fiscal sense!