A few years ago, a viral campaign promising eternal power supply, reduced road maintenance costs, and a free kitten chicken in every pot raised huge amounts of money. I’m talking, of course, about Solar Roadways. Companies and governments began experimenting with this idea shortly thereafter. We even visited one of the Netherlands installations (though they used a bike path instead of a road) back in 2014. Now that these initial installations have been up and running for a while, it’s time to see if they’ve performed up to snuff and delivered any kind of net benefit.
Spoiler alert: No.
One of the first solar roads at Tourouvre-au-Perche, France cost €5m to install and has a maximum output of 420kW, for a net cost of €11,905 (£10,624) ($14,011) per kW, as The Conversation details. While the road is supposed to generate 800kW/day, the actual yield is closer to 409kWh/day. With an average UK home using 10 kWh/day, that means the road (which covers an estimated 2800 m2) also generates enough power to feed 40 houses, with a capacity factor of 4 percent.
Capacity factor represents the theoretical rated peak power of the device against its actual output. No power plant has a literal 100 percent capacity factor, but 4 percent is quite low — even by renewable standards. The Conversation points out that a nearby solar plant at Bordeaux has a capacity factor of 14 percent and an installed cost-per-kilowatt one tenth that of the solar road. It produces 3x more power, at 0ne-tenth the cost.
As for Solar Roadways, its own project has fared even worse. The tiny test trial the company has done has a cost installed per kW of $32,363. But the power the company intends to divert for LED lights and buried heat panels to keep the roads melted results in a capacity factor that’s just 0.782 percent. If 4 percent is bad, 0.782 percent is beyond awful.
And all of this is before we touch on the other numerous downsides of solar roads. Roads are dirty. We drive large vehicles on them spewing chemicals that cloud the effectiveness of the collectors. The collectors will inevitably become dusty and grimy and require cleaning or polishing to restore function. They can be covered by road debris and snow, and they obviously don’t work in rain. The cost per mile is enormous, the benefits tiny, and the chance that we ever see any kind of meaningful value or improvement from these features is minuscule.
It turns out, sticking a fixed-location, off-angle panel on the ground, where people stand on it, scuff it, scratch it, and drive over it with incredibly heavy vehicles is a bad idea that may not generate much useful power. The Netherlands solar bike path made a little more sense, with its limited traffic confined to smaller, lighter vehicles, but it doesn’t look like solar roads have much of a future in the United States, no matter what. The power generation isn’t there. The efficiency is too low, the costs too high, and the benefits too small.
Top image credit: Getty Images
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