In 2016, the French government announced one of the most ambitious infrastructure projects in modern history: a 620-mile highway passing through Normandy built of solar panels instead of asphalt. The panels, the government said, would generate 790 kilowatts per day and power 5 million homes.

That ambitious plan flopped. In its first year, the road generated half the intended solar power. Normal wear and tear only reduced the output. Yet the public relations setback was a mere speed bump in the rapid emergence of a potentially life-changing technological advance. For an era craving creative ideas for battling climate change, solar roads may help society race to a solution.

From the Netherlands to America to China, governments, researchers and companies are developing roads that double as solar-power generators, transforming what the future could look like for both the global energy and transportation markets. It’s an approach that could turn the transportation industry — one of the biggest contributors to climate change — into a savior for the planet instead. They’re learning from the French project and its mistakes to build more viable alternatives, trying to dot the i’s and cross the t’s this time around.

In the state of Georgia, transportation lab The Ray is working with Wattaway — the company behind the French project — on its improved technology by testing it along the interstate highway system. The group has installed photovoltaic roadways along an 18-mile stretch of Interstate 85. Solar Roadways in Idaho, meanwhile, has focused on testing out the technology on a small scale, via parking lots, driveways and sidewalks.

A consortium of Dutch research organizations in March 2019 unveiled a 150-meter stretch of solar roads on a street and a bus lane. In 2014, the group had built SolaRoad, a 70-meter stretch of a bike path layered with solar panels, which produced 10,000 kilowatts in its first year. And in 2017, the Chinese city of Jinan, south of Beijing, opened a 1 km (0.6-mile) stretch of solar highway that generates 1 gigawatt of power annually — enough to support 800 homes.

“This technology could very well operate over sidewalks, bike paths and city streets,” says Allie Kelly, executive director at The Ray. “I can see it easily powering municipal smart-city technology at the very least.”

To be sure, the setbacks such as France’s failed attempt have also fueled criticism from skeptics. “Governments tout cool-sounding renewable energy technologies, but promises and funding fall flat because of the biases and inefficiencies of the public sector,” said Ross Marchand, director of policy for the Taxpayers Protection Alliance, in an op-ed for the Foundation for Economic Education in August.

But both governments and the private sector have learned lessons. Kelly says Wattaway is now better equipped to integrate its technology with the realities of wear and tear. “Our research has allowed the company to learn about how this technology will work alongside the road maintenance requirements in the United States,” she says.

As funding for solar technology grows — the Department of Energy in 2018 announced a $105 million investment in solar technology — the opportunities for researchers and firms to further fine-tune solar roads will only increase.

Genuine challenges in implementation do persist even as “using this transportation infrastructure to harness power has become a major selling point,” according to Nicki Zvik, CEO of Green Solar Technologies. Zvik, who is based in Los Angeles, says he has met with city officials and lobbyists who are reluctant to even broach the topic.

The major hurdle is that revamping roadways would play into the city’s budget, which is already set. “The best approach is to create new roads with this technology rather than replacing old ones,” says Zvik. China has done just that with its experiment in Jinan.

Critics have also pointed out that because solar panels on roads aren’t tilted at an optimal angle, their energy generation efficiency is not ideal. A solar road in a city square surrounded by tall buildings won’t get much sun. And if dust and mud start layering the panels, their efficiency drops still further.

Which is all why Solar Roadways in Idaho — owned by couple Julie and Scott Brusaw — is taking the slow and steady route, focusing first on smaller scales and preparing for the long haul. Julie says they weren’t surprised by the failure of the French project. “We feared that would be the case when we first heard about them rushing straight to roads,” she says. “We have always planned that roads would be our last application.” Instead, they’ve emphasized testing under different conditions on smaller stretches.

Solar Roadways is about to unveil a new model of photovoltaic roadways. The new model has been tested to handle the weather problems that the project in France was not prepared for. The company submerged its solar panels in a tank of water for several months to make sure they still worked fine. “That is important to know, as many areas are subject to flooding,” Julie says. “Every panel has heating elements to help prevent ice and snow to make walking and driving surfaces safer.”

The challenges won’t go away. But the advances in technology and the fast-expanding global interest are hard to dismiss. The day when you can charge your cell phone from the road you’re driving on might not be far off.