Science and technology

A future city centre? An artist’s view of solar panels embedded in the roads in Sandpoint, Idaho, the home town of Solar Roadways.The picture could be from any small town in the United States. The only thing that stands out is the colour of the road and car park in the town in Idaho: they have been surfaced with hexagonal plates that are green.

The plates are made of tempered glass and hide solar panels underneath. The road and car park produce electricity. The image is only an artist's rendition of the novel idea but a small car park complete with solar panels already exists in reality.

Electrical engineer Scott Brunsaw and his wife Julie Brunsaw are the founders of Solar Roadways, a company developing technology for generating electricity with solar panels embedded in the road surface.

The Brunsaws worked on their idea for a long time in the noughties before receiving funding from the Federal Highway Administration in 2009, which they put towards developing a prototype of a road with solar panels.

At the first phase, they tested the solar panels indoors. Research teams at universities focussed on the durability and traction of the glass surface and found that using tempered glass as a surface material was a feasible idea.

On the strength of these promising results, the Brunshaws were able to secure more funding, allowing them to produce a combined solar power plant and car park.

Now they have launched a crowdsourcing campaign to raise funds needed to gear up for production at a commercial level. So far, they have collected more than 1.5 million dollars.

Testing carried out in January and February revealed that the glass surface cuts the amount of electricity produced by panels by around 11 per cent but the technology still produces enough energy to make it a promising innovation.

Scott Brunsaw has calculated that if all the roads in the US were surfaced with these panels, the energy generated would be triple the current US energy consumption.

He erred on the side of caution in his calculation as it is based on winter conditions in Northern Idaho.

Roads work in the Netherlands

Solar panel roads have also been given the vote of confidence in the Netherlands, where the research organisation TNO runs a project on solar roads. The organisation speculates that roads with solar panels could produce more than a quarter of the energy used in the country.

TNO and a couple of its partners launched their solar power project around five years ago.

Both having started by developing solar powered cycling routes and car parks, the projects in Idaho and the Netherlands have many similarities but there are also differences in their approach.

Right from the start, Solar Roadways has also been interested in developing heating and lighting systems for roads while SolaRoad, the Dutch project, focuses on energy production.

Problems that remain to be solved include the storage of the electricity produced by the system.

"The electricity will be fed into the electricity grid. In the future, when we are building bigger SolaRoad applications, it is worthwhile to give some thought to the best way of doing this," explains Sten de Wit, a researcher at TNO.

"We will look into storing electricity locally and developing smart grids that balance supply against demand," he says, adding that TNO will build its first SolaRoad pilot on a 100-metre cycling lane in November.

The Dutch researchers have estimated that solar panels for roads cost around as much as conventional panels.

This is too expensive but the actual costs are cut by the extra benefits the road panels bring with them.

Electricity and information

The electricity generated by the panels in the road can be used for heating and road markings. Solar panel roads will have tunnels for cables to transfer electricity but these tunnels can also accommodate cables for the public electricity grid and information network, water pipes and other infrastructure.

Solar roads can also have sensors that collect information on the road use. In the future, the road surface can also be used for recharging electric cars. With new commercial solar power applications coming to the market, the electricity storage provided by roads can prove very beneficial.

Roads also have space, which can be at a premium elsewhere. People are not always keen to have solar panels installed on their roofs and walls, which may not have enough space anyway.

TNO has calculated that panels installed on buildings could only meet a quarter of the country's energy needs. Rural areas may also pose other problems.

The Ivanpah solar farm in California's Mojave Desert ran into trouble as questions were raised about its safety to tortoises, birds and other animals.

Road solar panels, however, seem to be animal-friendly.

One concern has been whether heating the road surface in winter would attract animals to come and warm up on it.

Brunsaw explains that they observed the car park, their pilot project, around the clock via a video camera to record animal movements.

Not one animal was observed.

Kalevi Rantanen – HS
Niina Woolley – HT
Image: Sam Cornett