Sun power.

Our roads take up a huge amount of space in our city centres. So why not put them to good use, and have them generate solar energy?

Electric might be all the rage when it comes to greener motoring, but there’s an even more ‘free’ energy – sunshine.

Car manufacturers including Swedish performance carmaker, Koenigsegg have flirted with the idea of a creating a solar-powered car. One man even recently broke a world record by crossing the United Arab Emirates in a solar-powered wheelchair. However, there’s one aspect of solar motoring that is yet to be exploited – the roads themselves.

Researchers from the University of Rhode Island (URI) have been looking into ways of using motorways to generate solar energy. They have four suggestions on how solar power can be harvested. The first idea would be to harness solar power from panels located in the pavement to heat water pipes placed beneath the road. This water could then be channelled beneath bridges to melt snow and ice or used to heat local buildings.

A second idea is to create a thermo-electric effect by linking two types of semiconductors – one hot and one cold – embedded in different places in the road. This would generate a small amount of electricity, which multiplied on a great scale, could be used to generate power for defrosting roads.

The third idea is to wrap motorway barriers with photovoltaic cells. These cells would then produce the electricity which powers the motorway’s lighting while also powering its road signs. But the URI team’s most exciting idea is to replace the roadways themselves with large electronic blocks containing photovoltaic cells, LED lights and sensors which would generate electricity and light up the roads.

Meanwhile technology company Solar Roadways proposes replacing all concrete and asphalt surfaces with solar road panels, which would power the businesses and homes around them. The US-based company hopes to start small by installing panels on driveways and in car parks, before moving onto public roads. It sees a future in which the energy produced by the roads is channelled into LED street-lighting or harnessed to heat elements which could melt ice and snow.

Swedish architect Mans Tham, meanwhile, has the biggest idea of all. He would like to see unsightly motorways covered up by his ‘Solar Serpent’. His vision is to construct a solar-panelled tunnel that would enable the huge swathe of land covered by the Santa Monica Freeway to serve a dual purpose. The Solar Serpent’s solar panels would provide energy for local businesses and housing, as well as power-points for recharging electric cars. It would also shade the roads reducing the need for air-conditioning in cars, while also reducing noise and fuel pollution too.