The Wattway concept to obtain electricity from road surfaces is the result of five years of R&D between two French partners – the National Solar Energy Institute (INES) and multinational Colas. The structure, designed to integrate the urban environment, generates electricity through light absorption thanks to photovoltaic energy. The panelling comprises slabs, each measuring 1.75 x 70cm, made of a substrate incorporating polycrystalline silicon cells, and including a compartment housing the electrical components. Easy to install, the structure is extremely robust in order to withstand the constant wear and tear from traffic. According to engineers at Colas, the service life of the slabs is between 15 to 20 years.
CONTRIBUTING TO THE SUSTAINABLE CITY… & COUNTRY
The technology has plenty of sustainability potential. Twenty square metres of Wattway could meet the energy needs of an average family. In urban areas, an entire road covered with the panelling could provide electricity to the surrounding environment, such as street lights and signals. One kilometre of Wattway road should be capable of powering the lighting for a town of around 5,000 inhabitants. On a much larger scale, a country like France could achieve energy independence through coverage of one quarter of all its roads, adds Hervé Le Bouc, managing director, Colas.
The French energy transition bill, adopted by Parliament on July 22, 2015, aims to build a comprehensive strategy for this shift, starting from the structural challenges the country faces to make its energy system sustainable.
A further strength of Wattway – its photovoltaic cells could prove beneficial for rural areas where sparse populations makes connection to the electric grid more expensive for users. Instead inhabitants could obtain energy from their local roads, thus becoming more independent. Note too that unlike solar plants, Wattway does not ‘grab land’; instead it intelligently exploits that already grabbed!
CLIMATE MATTERS
While a promising concept, Wattway could encounter problems in regions with extreme low temperatures, due to frost and melting ice. On the one hand, cold seems to make the system more energy efficient, and its resin material is resistant to the salt used for clearing the roads. On the other, secondary roads covered by snow receive less light and so generate less electricity. Since there have been no extremely cold winters in France over recent years, these issues still need to be fully explored.
HIGHWAY TO THE FUTURE?
Still in the test phase, this paving should be brought to market sometime in 2016. And Colas has ambitious plans – namely to cover more than one million square metres of roads by 2020! While this innovation is by no means the only solution aimed at creating new and greener cladding, it has the extra appeal of generating electricity.
Yes, the idea of employing an alternative to today’s ubiquitous asphalt concrete does appear unrealistic. After all, the latter is THE main material used for building and maintaining Europe’s highways. But let’s not forget that roads have existed for thousands of years, during which time a wealth of different surfaces have been laid, e.g. dirt, cinders, broken stone, cobblestones, limestone, granite setts, brick, and gravel. Will state-of-the-art Wattway be the next step in the history of the highways? Watch this space…!
Edoardo de Silva is a project collaborator with the independent Italian consultancy TRT Trasporti e Territorio
Cover photo ©COLAS – Joachim Bertrand
COP21, December 2-9, 2015: discover Wattway and a demonstrator at the Bouygues stand:
Galerie des Solutions / Paris – Le Bourget
By the by:
Several years ago, the French city of Toulouse was testing ‘intelligent’ lighting solutions adapted to the behaviour of its citizens.
Buses by Heuliez have been equipped with solar panels in the south of Brittany, France.