Which California site is the world's largest geothermal field?

The Geysers in California is the world's largest geothermal field.

Located in Sonoma and Lake counties, The Geysers is a dry-steam geothermal complex that uses underground heat to produce electricity. Development began commercially in 1960, when the first generating unit started operating. The field is spread across a large area of northern California rather than being a single power station.

Steam from underground reservoirs drives turbines directly. Over time, production declined as pressure in the reservoir fell, so treated wastewater has been injected into the field to help replenish it. This water-reuse project became an important part of maintaining output.

Italy's Larderello is older and historically important: it hosted the first geothermal power demonstration in 1904. However, Larderello is not the world's largest geothermal field, a distinction held by The Geysers.