Geothermal energy is produced by the heat of earth's molten interior. The extremely hot rocks present below the surface of the earth heat the water and convert it into steam. So, two holes can be drilled into the earth in the region of hot rocks and two pipes can be put into them. From one pipe, water is supplied into the earth. Hot rocks convert the water into steam. The steam so formed comes up through the second pipe and run turbines to generate electricity.