Geothermal energy has been used for making electricity since 1913, starting with the Larderello 1 power plant. This plant used steam from hot underground water to generate electricity. Over time, more geothermal power plants have been built worldwide. In the United States, these plants were constructed in the 1930s, 1960s, and by 1968. The Earth's heat can be harnessed to create electricity, and this technology has been improving and expanding for over a century.