Many roads in Icelandic cities have under-road heating systems that keep the streets free of ice and snow even in the coldest of temperatures. They work more or less like underfloor heating in homes: warm water runs through looped tubes laid in the tarmac a few centimetres below the surface of the road. Natural geothermal energy is used to heat up the water. It is very easy to tap geothermal energy in Iceland, where a number of active volcanoes are continuously heating the Earth’s crust.
It is also possible to heat up roads by running electricity through heating elements. But this method is not as beneficial for the environment as geothermal heating.
Saskia Blank of the Ideas 2020 team answered this question.