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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."
at least one of the claims here seems a little off: http://www.solarroadways.com/The%20Numbers.htm
in particular, this sentence: "This means that if each individual panel can be made for no more than $6912.00, then the Solar Roadwayâ can be built for the same cost as current asphalt roads." It seems to assume that an outlay of 3x the money for a road that lasts 3x as long is the same cost as 1x & 1x respectively. While this is true for someone with infinite readily available money, the reality is that most places don't have enough money for that.
also "The Solar Roadwayâ will, therefore, eliminate half of the greenhouse gases currently being produced. " seems to be a dramatic overstatement.
Concrete is solid like a rock. The reason concrete cracks in the weather is because it expands and contracts because of the temperature and water content. If the solar panels were a lot more pliable, just as strong, waterproof, and had something like the self healing plastic abilities, I think it can work just fine.
...Also why do they have to make roads out of them.. where did that come from? Just put them out on land somewhere, you don't have to drive all over them.
This was my first thought too. Making the solar panels into roads (or vice versa) is compounding the problem. Just put the 25,000 mi^2 of solar panels in the middle of the desert and call it even. Adding a layer of glass or some sort of protective surface is going to lessen the efficiency and raise the cost of production and maintenance. I'm all about green energy, but there are better places we could be spending our money and energy.
Back at uni, I did a mini-course on the the Solar Car challenge, because my University made some of the solar panels for the top cars, and we also had a car that entered and did fairly well (for a low budget). One of the things we learned was that solar cells lose efficiency very quickly from a variety of things. The two that most researchers ignored in the lab but mattered in the field was heat and dirt. The cars in the race are washed with cold water thoroughly at every opportunity because colder, cleaner cells are substantially more efficient. Think CPU overclocking - lower temperatures improves things a lot.
Now lets compare this situation to a typical road which is:
a) Blistering hot most days.
b) Really, truly, thoroughly dirty.
Sounds like the perfect place to put an expensive solar cell panel!
Another thing we learned is that a single "test" panel in a lab operates very differently to a bunch of real panels in the field. What a lot of naive researchers miss is that the amount of sunlight over the entire collecting surface in the real-world is not constant. For a one-square-foot panel, it is, but for any significant surface (the size of a car, road, whatever), it won't be. The surface will be curved or partially shadowed. This matters a lot because if you just connect a bunch of cells together, they perform roughly the same as the worst of the lot. If there's a few cells under a shadow, that's drags down the efficiency of the panels receiving sunlight. To efficiently extract energy from a bunch of panels receiving differing amounts of light takes a bunch of expensive power management electronics that can combine the different cell outputs in the right way.
In practice, cells are so expensive that the best place to put them is on huge, flat, orientable panels out in the desert where there's no clouds, no rainfall to cake dirt onto the panels, and they can be oriented to face the sun at all time, like this array in southern California.
Can we stop acting like the cars are driving directly on top of the solar cells? They're not. They're driving on glass, treated for greater impact resistance and a textured surface. The question should be, how well does treated glass withstand winter damage?
Dear Lord: I don't want to go back to college, so please help me be sexy. Amen.
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. ;)
Dear Lord: I don't want to go back to college, so please help me be sexy. Amen.
Is reading the FAQ too much to ask?
Try this: Go to Google Maps and start looking at roads. Random roads. Select without bias. Tell me how much of the road surface is covered on average. Then go deliberately seek out traffic, and again, tell me how much of the road surface is covered.
Even in "bumper to bumper" stop-and-go traffic, about half the roadway is exposed. On average, a quick glance at the US's road system suggests that perhaps 98% of it is exposed at any point in time during the day, and perhaps 90% in cities.
Dear Lord: I don't want to go back to college, so please help me be sexy. Amen.