Glow-in-the-dark roads

As cash-strapped local authorities look to save on energy costs by switching off street lamps in the dead of night, Dutch designer Daan Roosegaarde has unveiled plans for ‘smart highways’ that include glow-in-the-dark white lines and a road that lets drivers know if conditions become icy.

When the white lines at the side of the road are treated with photo-luminescent powder they can emit a glow for up to ten hours at night without the need for electricity.

Perhaps the most unusual proposal is for the road surface to display ice crystals when the conditions become cold and slippery. The innovation is made possible by the use of dynamic paint that responds to changes in temperature.

Full-scale examples of these concepts will be built in 2013 in the Netherlands.

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Roads that produce electricity

The photo-luminescent markings being installed on streets in the Netherlands does not require a power source, but a new type of road developed in Israel uses crystals embedded in the asphalt to turn the vibration caused by cars into electricity.

Engineers at the Technion-Israel Institute of Technology in 2008 claimed the piezoelectric crystals were capable of producing up to 400 kilowatts from a 1-kilometre stretch of dual carriageway.

A spokesperson for the Environmental Transport Association (ETA) said: “Many predict a massive shift to electric cars, and it may be the roads themselves that help provide some of the power needed.”

How much power can a road produce?

The amount of power generated by these crystals is relatively small – 400 kilowatts per kilometre of dual carriageway – but if the production of the crystals is environmentally benign this system could be a silver lining to the problem of heavy traffic.

To put the amount of energy produced in context, 400 kilowatts per hour is enough to run 8 Ford Fiestas.

What is piezoelectric?

The term piezoelectric relates to the ability of some materials to generate electricity when they are squeezed or pressed. In the case of the power generating road, it is the weight of passing cars that ‘squashes’ the crystals and causes them to generate power.

If their production and installation is environmentally friendly, then piezoelectric crystals may provide a green, if limited, supply of power.