This lecture discusses the promising potential of geothermal energy as a renewable source, highlighting technical complications and the varying estimates for its future role in energy systems. It explores the different ways geothermal energy can be harnessed, focusing on its applications for heating purposes and the challenges related to its implementation. The lecture also emphasizes the importance of geothermal energy for heat production, its constant availability compared to other renewable sources, and the limitations and efficiencies of geothermal power plants.