Geothermal handbook: PlanninG and Financing power Generation t e c h n I c a L r e p o r t 2 / 2

CurrENT uTILIzATION OF gEOThErMAL rESOurCES
Electricity has been generated commercially from geothermal steam since the early 20th century, and 
geothermal energy has been used for direct heating purposes since ancient times.
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However, the 
development of geothermal power generation started in earnest in the early 1980s and can be partially 
understood as a response by power producers to the first oil crisis in 1972. It has taken around 40 
years to develop the existing 11 GW of currently installed power generation capacity (Figure 1.7). 
Geothermal resources have been identified in nearly 90 countries, with geothermal utilization recorded 
in more than 70 countries. As of 2010, electricity is produced by geothermal energy in 24 countries. 
Iceland and El Salvador have the highest share of geothermal power in their country energy mix, 
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Scaling refers to the formation of a deposit layer (scale) on a solid surface (e.g., in a boiler, pipeline, heat exchanger or other equipment of 
the power plant) or within the steam field, including in the wells.
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The term “direct use” refers to applications other than power generation (e.g., home heating, bathing, greenhouses, cooling, etc.).

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