Work has began installing underground sensors across Aberdeen as part of a university-led project to assess the city's geothermal energy potential.
Approximately 100 small seismic nodes are being buried underground in green spaces from the Bridge of Don to Nigg areas as well as in the city centre.
The project, led by the University of Aberdeen, will explore the potential for use of geothermal technology, which involves pumping cold water deep underground to be heated by the earth before being brought back to the surface.
The nodes will track natural vibrations from wind, waves and traffic, the BBC reports.
The data will then be used to create a 3D map of granite as deep as 5km below the city surface which will help pinpoint locations where geothermal heating would work best.
Dr Amy Gilligan, a researcher with the Aberdeen Geothermal Feasibility Pilot (AGFP), said: "This marks the beginning of an exciting stage of the project.
"By placing these small sensors in the ground, we can safely and quietly listen to natural vibrations and build a picture of the rocks deep below Aberdeen."
She continued: "Most people won't notice the sensors once they are in place.
"But what we learn will help us understand whether geothermal heat could one day provide a clean, local source of heating for homes and public buildings, reducing carbon emissions and support a more sustainable energy future for Aberdeen."