8 February, 2016

Solar powered roads – a breakthrough in the tackling climate change?

We have all seen or at least heard of solar powered cars (or solar powered buses). Vehicles that can run entirely on the power of the sun are astonishing, yet we all know that at this time we would never own one instead of our regular petrol or diesel fuelled cars.

But there has been a new thought on how solar power can be applied into our transport system; through solar powered roads. It might seem ridiculous at first, but given that any point of road is exposed to the sky 90% of the time this is a lot of space that could be utilised. Also the infrastructure is already there, roads reach almost everyone across the country and an electricity transformer will never be far away.

It will be much more likely that you will see a solar powered road before you see a solar powered car for public use. By spring this year, the first solar powered road will be unveiled. In the next 5 years the French government plans to transform 1,000km of its road network with inbuilt solar cells. The ‘Wattway project’ by the French road and rail infrastructure company, Colas, will be able to provide enough power for a village of 5,000 people.


The idea of harnessing solar energy from roads is certainly not a unique idea. In November 2014, a 70m bicycle pathopened between the suburbs of Krommenie and Wormerveer in Amsterdam, Netherlands. The path, which cost £2.4m to build, utilises solar cells covered in tempered glass and is due to be extended to 100m, providing enough power for 3 homes. TNO, the research institute behind ‘Solaroads’, say that the possibilities are endless; from providing electricity to the traffic lights to even powering electric cars in the future.

So, will ALL the roads of the future be solar powered?

Scott and Julie Brusaw seem to think so. The couple from Idaho have been developing their own vision for solar powered roads since setting up the company ‘Solar Roadsways’ in 2006.

Through the crowd-sourcing website ‘Indiegogo’ they received over $2 million, double the amount of funding they initially set out for. Many donators were drawn to the project because of the sheer ambition that the couple had, as well as the many functions that their prototype was capable of.

Their design for solar powered roads has been far more elaborate and ambitious than any other; with the use of LED lights, pressure sensors and temperature regulation they are more like computers than roads. By their own estimates they say that if every road in the U.S. had their solar roads they could provide three times the amount of power the country currently uses; all without the use of fossil fuels.

LED Lights

Since 2006 the Brusaw’s ideas for solar powered roads have been boundless. With programmable LED lights they foresee that future roads could adjust traffic signals to meet the needs of the individual road user.

LED lights could also prove popular in places other than the road too, such as car parks to assign spaces, recreation parks to change layouts and also to improve the aesthetics of pedestrianised roadways.

Pressure Sensors

Solar Roadways would also be pressure sensitive to detect hazards on the road. For example if a tree has fallen over the road will communicate the problem to a central control centre, and also through the use of LED lights, travellers will get early warnings of the obstacle as they approach. The roads could also sense animals wandering into the road, as well as pedestrians and vehicles involved in collisions. By detecting the speeds to which motorists are travelling the roads could also issue ‘slow down’ signs as well as a reminder of the speed limit.

Looking further into the future, the solar roads could even convert the energy of cars running over it to electricity, with some pioneering technology this power could even go back into the vehicles.

Temperature Regulated

One of the most appealing aspects of the Brusaw’s solar road is the temperature adjustment feature. This would melt snow as it hits the road surface, which if it works, it could be a revolutionary concept as the economy will no longer be hindered by the weather. Commuters will no longer be stuck in traffic and will be able to reach their place of work. Also there would be no longer be the need to layer roads with salt, which if you weren’t aware, corrodes the underside of vehicles. Cyclists and motorcyclists will also benefit as they could still ride any day of the year without the danger of skidding.

National Grid

The Brusaw’s say that their solar roadways will completely transform the national grid, as it will give areas devoid of power access to electricity. Furthermore the national grid will be completely decentralised; therefore it would reduce the threat of terrorist attacks or natural perils that could disrupt the electricity supply if a power station is disabled.

But the future may not be that bright…

It’s hard to not feel optimistic by the Brusaw’s invention. I mean who doesn’t want the future to look like freakin’ TRON? The Brusaw’s video makes the idea too good to be true and unfortunately that is exactly the case; the prototype has too many fundamental flaws that ultimately make it impractical in reality.

Firstly there is the price. Of course solar roadways would be far more expensive than the current asphalt or concrete roads as they require far more resources to build. A conservative estimate to the price of a solar road would be $20 million per mile. With the added element of electronics imbedded into the road, the cost of maintenance would be far greater and the expertise to repair the infrastructure would be much more demanding.

Another obvious problem with solar powered roads is that they need to be laid flat on the ground. Yes, this does mean that they are upwards facing but by not being angled at the sun each solar panel loses about a third of its total potential energy conversion. Would it not be easier and cheaper to build a solar power plant that would more efficient?

The tile design itself is another issue. There is a reason most roads are made from either concrete or asphalt these days and that is because they require far less maintenance than the brick and cobbled roads of the past. As vehicles drive over more pressure is put on the outside than the centre of each tile or brick than the centre. As these electronic tiles cannot be fitted in place, over time they would shift position which would be a hazard to all road users.

It’s not looking good for solar roadways so far, and it’s about to get worse. The idea of having LED fitted into the road is a fantastic idea; at a glance. The actual functionality of LED lights in daylight is much to be desired. LED lights do operate during the day, most notably on traffic lights, but if you will also notice that traffic lights are kept in the shade so that the lights are bright enough to see. However putting these lights under the road surface and facing the sky they become almost impossible to see. It is also true that some billboards use LED lights without shade but the power required for them to appear in sunlight is greater than can be generated from solar panels.

A further reason solar roadways would not work is the driving surface. If you were paying attention to the video earlier you would have noticed that the tiles would be made of glass. That’s right, glass. The Brusaw’s say that their specially made tempered glass is designed to maintain traction with tires just as normal roads do, but I would still not want to test it out in wet conditions. But the real danger with glass is not skidding. With millions of vehicles driving over the glass would unavoidably be scratched and eroded. This would not only affect the ability of lights to shine through and for sunlight to be absorbed but it would also grind the glass down into tiny fragments, which would lead to some serious health problems.

Now we get to the temperature adjustment feature which would be a fantastic innovation for everyone that cannot drive well in the snow or isn’t Finnish. But again we return to the issue of the solar cells ability to produce enough energy for the feature to actually work. During the winter the northern hemisphere receives less sunlight, meaning less power. Also if snow does build up then the light would be blocked from the road, thwarting the ability of the solar cells to produce the energy needed. The roads would also struggle in conserving the energy too because smarter and more scientific minds than me have said so.

For all of these points discussed, the British scientist Phillip E. Mason a.k.a Thunderf00t comprehensively explains in these 3 videos why solar tiles would not work.

The Wattway Project

The solar roads that will be unveiled this spring in France are very different to the Brusaw’s prototype. The Wattway project is far less complex, as it will simply produce electricity from the sun, not power lights, generate heat or include pressure sensors.

It also would not involve tearing apart the existing infrastructure as these solar cells can simply be placed on top of the existing tarmac. Importantly the solar cells would be made from silicon rather than tempered glass and it has been made to perform just like normal roads as they claim it is skid resistant.

Whether the Wattway project will be a success or not remains to be seen. It is certainly a simpler design to ‘Solar Roadways’ so we cannot write it off just yet.

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