Above, a rendering of Solar Roadways photovoltaic pavers in Sandpoint, Idaho, home to the technology's developers.

Solar power has an area problem. Unlike fossil fuels, which pack large amounts of energy into small volumes, solar power relies on each unit of area delivering relatively small quantities of harvestable energy. When it comes to building-integrated photovoltaics, this fact privileges groundscrapers—low-slung structures with roofs that make up a large portion of the envelope. Geometrically, small structures and towers are not as effective as their wider and shorter counterparts since compact buildings lack adequate surface area for solar collection and tower façades generally collect less energy than roofs due to incident sun angles.

Given these limitations, Idaho-based entrepreneurs Julie and Scott Brusaw looked to another, yet-untapped component of the built environment to collect solar energy. Solar Roadways is a multi-functional paving surface powered by the sun. Citing that the U.S. alone has some 72,000 square kilometers (27,800 square miles) of concrete and asphalt paving, the Brusaws developed a proposal to harness up to three times the current U.S. energy demand by using roadbeds and parking lots as energy collectors.

Solar Roadways consists of interlocking hexagonal pavers made of high-strength, textured glass embedded with photovoltaics, LEDs, and sensors—a compelling example of infrastructure-integrated photovoltaics. The Brusaws developed two phases of prototypes with funding from the U.S. Federal Highway Administration. Their initial objective is power generation; Solar Roadways is designed to provide energy to neighboring homes and businesses. Some of this energy is also used to power programmable LED lights for lane lines and signage, and to allow the road to self-heat and melt snow and ice. Though the pavers have no batteries to store energy, their nocturnal power demand is offset by their diurnal energy supply to the grid. The designers anticipate that Solar Roadways will one day power electric vehicles, either via parking lot–based charging stations or direct induction through the road surface.

The prototype pavers undergo testing.

The next-step is full-scale production. On April 21, the Brusaws launched a crowdfunding campaign on the Web-based platform Indiegogo with the goal of raising $1 million to help grow their team and streamline production. Even if the project doesn't meet that mark, Indiegogo allows them to keep any funds raised for use on the project. The campaign will run through May 31.

Mass production will allow the Brusaws to address remaining questions, such as how a system of hexagonal units will conform to the curvilinear geometries of winding roads and turning radii; how to stomach the high initial cost and embodied energy of a glass roadway; how to prevent the interruption of safety lighting in the event of an electrical malfunction; and how the incorporation of cable corridors can effectively handle large quantities of storm water. Nevertheless, the Solar Roadways project offers an intriguing vision for technology-infused infrastructure that addresses solar power’s surface-area-to-power-generation conundrum.


Image courtesy of Julie and Scott Brusaw on Indiegogo.