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Why Solar-Powered Roads Won't Work

We’re as excited about the proposal to develop solar roadways as anyone. The only problem? They won’t work.

Solar-powered highways sound great. But will they actually work?    

An ambitious plan to build solar roadways across the country sounds almost too good to be true. And guess what? It is.   

First, some backstory: A two-person startup called Solar Roadways wants to pave roads with solar cells, and they’ve already secured almost $2 million in crowdsourced funding. The basic idea is pretty simple. The solar road would use existing asphalt as a base layer, while the tempered-glass cells would generate about 52 watts of power each and last about 30 years.  

The company’s math is quite compelling—if all the asphalt roads in the U.S. were paved with solar cells (about 31,000 square miles of land), they’d generate three times the electricity we use today. And the potential interface between the roads and future electric cars (with the solar cells providing wireless power to undercarriages) also sounds great. And it gets even better. This “information superhighway” wouldn’t only generate power for cities and cars, but also for powerlines and fiber-optic cables.

You might also be wondering how tempered glass is supposed to hold up to all this abuse. Well, the company claims the new roads can withstand vehicles weighing up to 250,000 pounds. In fact, Solar Roadways claims that a tank convoy could traverse the road. (It also admits that the material it plans to use hasn’t yet been load-tested tested in an environmental chamber.)  

With a small town in Idaho promising to build a solar parking lot and a bike path this year to test the technology, and with plans to move from prototype to production relatively soon (although there’s no mention of exactly when or where), the road to the future seems to be coming along nicely, right?  

Um, not so fast. There are some potholes in the plan.  

One seemingly mundane question has to do with tire marks. You’ve seen them—skid marks on the highway that look so dark you wonder what terrible accident occurred. Solar Roadways says it hasn’t yet tested the effect of car tire marks on its solar cells. Instead, it’s only used bike tires to see if these black streaks impede power generation. The company claims the answer is no, but we’re still waiting for more data during the next round of testing.     

Then there’s the question of funding. In several of the FAQ comments, Solar Roadways says the cells “pay for themselves.” Back in 2011, I asked noted Gartner automotive analyst Thilo Koslowski if the project sounded feasible. His main objection at the time? That building solar roads would cost several billion dollars and require serious government and taxpayer involvement. We’re still waiting to hear from the company regarding how much it anticipates the next phase of the project will cost, although it claims we should have those numbers later this summer. 

There’s no data available about what would happen to the road after a year of heavy commuter traffic, trucks, and buses following their routes on a daily basis. And the effect of skid marks and the everyday abuse roads must take from the elements is still unclear.  

The takeaway? While we’d be stoked to see this idea succeed (sounds like a win-win, right?) the tech is still untested. Solar Roadways hasn’t made it obvious, from its FAQ or the crowdfunding campaign, what its long-term plans entail, how much a stretch of road will actually cost, or when the company will start building working models. 

 

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