Solar road paves the way for sustainability

Asphalt roads and driveways could be converted into giant solar panels if a system installed in a car park in Ullapool, north-west Scotland proves a success.

Invisible Heating Systems’ road energy system uses the heat of the sun to warm water stored in pipes 3cm below the surface of its new car park.

“We first thought of the idea when we saw sheep lying on the road at night to keep warm,” said company founder Henk Verweijmeren. “Roads absorb a lot of radiant heat even if it’s cloudy and the water under the road can reach up to 45°C in the summer.”

Passing water through pipes helps cool the surface of the road in summer and warm it in winter. “This halves road
maintenance and doubles the road’s life expectancy,” said Verweijmeren.

As well as improving the condition of roads, the system also generates considerable heat energy. “We will generate the equivalent of 108MW of heat energy each year from our 400m2 car park,” he added.

In order to tap into this energy source in the winter when it is most needed, the solar-heated water is pumped into the aquifer below the site.

“Ground water in the UK is typically between 8°C and 12°C – not enough to heat a building without using a heat pump,” said Verweijmeren.

“But adding warm water to the aquifer means water can then be withdrawn in winter at 20°C to 30°C. In an industrial building that only needs to be heated to, say, 15°C, in winter you don’t even need to use a heat pump.”

The system has already been used on a number of projects in Holland and the company is in talks with three potential clients in the UK and Ireland.

“There are so many potential benefits,” he added. “It will be ideal for runways at airports and then there’s the impact on the wider economy in improving the road network and reducing congestion caused by repairs.”