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23.5.14

Note to Hippies: Make Love, Not Roads

This post has gotten a frightening number of hits in the last few days (over 500). I've decided to clean it up a tad and clarify a few points. The intent of this post was to point out issues that I did not find adequately addressed in either the solarroadways.com website or the Indygogo page.  Photovoltaics have a place in energy production - just not under the tires of an 18-wheeler. 

What follows is strictly my opinion.


My buddy posted this on Facebook today and I'm pretty sure I'm like one more pedantic comment away from getting "unfriended."
Source: http://solarroadways.com/intro.shtml
"Solar roads? Where do I even start with this?!"

At first glance it seems like a no-brainer, right? In general, I am a huge fan of solar energy. A big area that is static and often empty could easily be filled with PV panels.

The world needs dreamers to push technology forward and challenge innovation. All due respect to Scott and Julie Brusaw, I see many problems with this concept.

Problem 1:  Solar energy needs a smooth, clean surface for optimal efficiency. Roads get really really dirty. Dust, tire schmutz, oil and smeared raccoon carcasses cloud the issue.

Problem 2: Speaking of clouding the issue, think about the glass. The same roughening they used to make the stuff non-ice-rink-like also impedes sunlight from hitting the PV cells.  Additionally, they are talking about using recycled glass. Recycled glass contains impurities that would also impede efficiency.  Even if the recycled glass were purified they should not use mixed color glass. Also, to make it nice and thick for load bearing - again, less light hits the cells.

Problem 3: References, please? I couldn't help but notice that none of the magazines where this was featured are scholarly or civil engineering related. The FWHA funds a lot of wacky stuff in phase 1 so that is not an indication of feasibility. I want to see the university studies. I want to see the Booz Allen Hamilton data*. I want to see a serious article in ENR or ASCE Journal.

Problem 4:  Want to get a snowplow driver excited? Ask him his opinion on embedded reflectors. He will probably curse up a storm and tell you stories of damaged plowblades or laugh and tell you how he pulled up 10 miles of reflectors in the blizzard of 2011. The reason is that it doesn't take much for mother nature to push up a little corner of a modular object (known as frost heaving), therefore making it non-flush with the road surface. Expand this headache to every square hexagon of roadway, and you see this is going to be an issue.

Problem 5: Drainage, in my opinion, is one of the biggest problems. Note that all of the prototypes are planar surfaces with a trench on either side. Supposedly, one trench is for electrical and data and the other is for storm water. The geometry of one of today's roads is such that water drains to both sides. They are going to need to re-think the shape of the modules to accommodate for changing crown conditions. Either the cross-section of the road will need to change or they are going to need water-proof channels for electrical components. A good way to get around this problem is to put the stuff overhead, which they say is unsightly. Also, nobody treats highway runoff.

Problem 6: This technology does not preclude potholes. The cause of a pothole is usually the sub-base getting washed out by water or that pesky frost heave I mentioned earlier. You'll still get potholes and some county worker is going to level it out by throwing a scoop of asphalt on top of the panel.

I know I'm being totally pessimistic but I will run down one of these for its entire length butt nekkid if I ever see one installed.

*Booz Allen Hamilton is the engineering research firm that contacted the Brusaws about conducting feasibility studies. No data has been made available to the public (that I could find).