What are they?
Solar roads are exactly what they sound like: solar panels made from toughened, recycled glass, with a texture that provides as much grip as conventional roads. By installing hundreds of individual panels the inventors claim that it will be possible to build a road that will generate enough electricity to pay for itself in the long term. Advocates envisage a world where thousands of miles of sun-baked asphalt are replaced with roads that supply electricity and improve road safety
What are the benefits?
The advocates of solar roads claim many benefits beyond the obvious energy generating potential. For instance:
- Solar roads will contain heating elements to prevent snow and ice forming during winter months, saving money on gritting and maintenance whilst reducing delays and accidents.
- Panels will be pressure sensitive, allowing them to monitor traffic levels and identify where roads have been blocked by fallen trees or landslides.
- Each panel will contain programmable LEDs, allowing road markings to be changed remotely and advising motorists of upcoming traffic jams or obstacles.
- Because each panel is a separate unit, Individual panels can be removed for repairs without the need to resurface large areas.
The US Department of Transportation (DoT) have awarded two rounds of research funding (worth $850,000) to Solar Roadways Inc so far, saying that early results are encouraging and that the idea is receiving widespread support. However, the DoT cautions that manufacturing costs are still very high because each solar cell is currently manufactured by hand.
What are the drawbacks?
Besides the cost of materials, which raise big questions around the business case for the product, the largest concern is likely to be safety.
Some experts are sceptical about the potential of textured glass to stop traffic as effectively as asphalt, which is specifically designed to increase traction. Despite the DoT’s funding, there have been difficulties testing the solar roads and to date safety assessments have relied on computer modelling, rather than practical testing. There are also questions about the durability of the toughened glass panels, although the fact that panels can be replaced individually may go some way to reassure sceptics.
Will they ever be a reality?
While the US continues with R&D, France have recently announced that they will be building 1000km of solar roads. Locations are still to be confirmed but it is hoped that the road will provide enough power for one household per metre.
Meanwhile, in the Netherlands solar roads have technically been in operation since 2014 in the form of a 70m long bicycle path on the outskirts of Amsterdam. This represents the world’s first functioning solar road, but at a total cost of $3.7 million (around $53,000 per metre) it may be a while before the technology is widely adopted. Moreover, French predictions about the amount of energy produced may be in for a reality check as the 70m Dutch road reportedly produces enough power for only three households.
The fact that the US crowdfunding campaign for Solar Roadways Inc has already raised over $2.2m suggests that, whatever the practical difficulties, there is significant public appetite for the concept.