The Geysers, California (1960s–1970s)
About 80 miles north of San Francisco, The Geysers became the first large US geothermal field. Utilities built steam turbines there starting in 1960, and development accelerated during the 1970s energy crisis as Congress created tax credits for geothermal power.
By the mid-1980s The Geysers was the world's largest geothermal field, supplying baseload power to northern California's grid.
It proved geothermal could deliver reliable always-on electricity, but conventional hydrothermal resources stayed limited to volcanic regions with naturally hot water near the surface.
Today's boom targets the same resource, but new drilling techniques adapted from oil and gas aim to tap deep hot rock far beyond The Geysers' natural reservoirs.
