When cities run out of space for solar panels on rooftops, one of the next places to turn could be roads—or bike paths. In the Netherlands, one of the country’s newest bike paths doubles as a solar energy generator that could eventually help power surrounding neighborhoods.
«In the Netherlands, we have about 140,000 kilometers of roads—enough to go three times around the world, and more. It’s a huge area, more than all of the rooftops combined,» explains Sten de Wit from TNO, the research organization that helped create the new bike path.
«We already put solar panels on rooftops, and this is a process that is going faster and faster,» he says. «But if we look at the goals we have for sustainable energy production we need more area than just rooftops. If we can put panels in a road which is there anyway—then we can get that function and lots of green energywithout disturbing the landscape or taking extra space.»
TNO worked with engineers and local government to develop a paving system, called SolaRoad, that could generate power while still holding up to traffic. «If you put a normal solar panel on the road, you’d have two main issues—one would be that it’s slippery especially when wet, and two, it would probably break very quickly,» de Wit says. «Those were the two main challenges we had to solve. It also had to be transparent enough that light could reach the solar cells.»
The new bike path is a pilot, and the researchers will use it to gather all kinds of information, including how much energy this type of road can generate. «Based on what we’ve done in the lab, we think the energy gain will be between 50-70 kilowatt hours per square meter per year,» de Wit explains. A typical Dutch household could be entirely powered by about 50 square meters of roadway.
The pilot path will mostly handle bike traffic, but also the occasional car, and the researchers plan to keep developing the technology for use on regular roads (in a similar way to the U.S.-based Solar Roadways project, which claims that solar roads could power the entire United States).
They also hope to take the technology beyond the Netherlands. «The Netherlands is not the most sunny country in the world,» says de Wit. «So if we go further south, it’s very likely that this product will be at least as interesting there as it is here.»
The technology isn’t cheap—the pilot bike path cost $3.75 million dollars for a narrow stretch of only 230 feet. But as the development progresses, the cost is expected to come down. And since it generates power, it can slowly start to pay for itself.