The document discusses geothermal energy, which is the heat energy stored in the Earth that can be used to generate geothermal power. California has the most geothermal power plants of any state, with 33 plants producing around 90% of the nation's geothermal electricity. While the upfront costs of installing geothermal systems can be high, the investment pays off over time through lower energy costs. However, geothermal requires a large land area to lay piping.

1. Geothermal Energy g