Millions of French People Could Get Energy From Roads Covered With Solar Panels

Imagine miles and miles of roadway stretching towards the horizon, glinting under the afternoon sun. Now, imagine those same roads transforming the sun's rays into enough power for millions of people.

France has revealed plans to do just that.

Ségolène Royal, French Minister of Ecology, Sustainable Development, and Energy, announced in January that some 1,000 kilometers (621 miles) of roadway would be covered with solar panels in the next five years. If successful, the project could provide enough energy for eight percent of the French population, or over 5 million people.

While it might sound too good to be true, Colas, the road construction company behind the project, assures it is not. The company revealed the solar road project, "Wattway," last October, calling it the "fruit of five years of R&D in a partnership with the French National Institute for Solar Energy." Hervé Le Bouc, CEO of Colas, said the project was "unique on a global level" and key to the future of transition energy production from coal, oil, and natural gas to renewable forms of energy from the wind and sun.

Though on a much smaller scale, the Netherlands launched a similar project in November 2014 in the form of a 70-meter bike path. Since its launch, the project, SolaRoad, has produced more solar energy than anticipated. In the first six months, the bike path generated over 3,000 kilowatt hours, or enough to provide electricity to a single-person household for a year.

In France, the Wattway project will work with existing roadways and infrastructure and avoids one of the big concerns about large-scale wind or solar installations."Wattway produces electrical energy without overtaking farmland or natural landscapes, and contributes to increasing the share of photovoltaic electricity in the energy mix, both in France and worldwide."

"There is no need to rebuild infrastructure," Le Bouc told French magazine Les Echoes last year. "In Chambéry and Grenoble, we tested Wattway with success under a cycle of 1 million vehicles, or 20 years of normal road traffic, and the surface does not move." According to the French Environment & Energy Management Agency, one kilometer-long section of Wattway-paneled road has the potential to power the street lights of a town of 5,000.

Jean-Luc Gautier, manager of the Center for Expertise at the Colas Campus for Science and Techniques, said in a press release that the Wattway project, now protected by two patents, began with a simple reflection. "Roads spend 90 percent of their time just looking up into the sky. When the sun shines, they are of course exposed to its rays. It's an ideal surface area for energy applications."

According to Colas, the solar panels — composed of photovoltaic (PV) cells embedded in a multilayer substrate — are designed to withstand any kind of roadway traffic, including trucks. The company calls the translucent panels of photovoltaic cells a "perfectly watertight layer cake," and describes the surfaces as weather resistant, durable and safe, equally skid-resistant as conventional asphalt. Only several millimeters thick, the panels can be added to existing roads, highways, bike paths, and parking lots, and are designed to be adaptive to the natural thermal expansion of pavement.

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Critics of the project say solar roads are not cost efficient and that the Wattway project seems more of a way to subsidize French companies than a sustainable alternative energy solution.

Mark Jacobson, an engineering professor at Stanford University, wrote on Twitter, "Solar roads in France much less efficient/costly than PV over rooftops & parking structures, & in PV power plants."

According to Le Monde, Royal has proposed between 200 and 300 million euros be raised for infrastructure improvements, including solar roads, by increasing taxes on diesel.

Installation of Wattway — what is being dubbed "the revolutionary road" — is scheduled to begin this spring.

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