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

geothermal resource Availability, Typology, and uses
what is geothermal Energy and where is it Found? 
Geothermal heat is constantly produced by the Earth from the decay of radioactive material in the core 
of the planet. The heat is moved to the surface through conduction and convection. In the crust, the 
temperature gradient
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is typically 30°C per kilometer but can be as high as 150°C per kilometer in hot 
geothermal areas. 
If even a small fraction of the Earth’s heat could be delivered to the points of energy demand by 
humans, the energy supply problem would be solved. The global technical potential
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of the resource is 
huge and practically inexhaustible. However, tapping into this tremendous renewable energy reservoir 
is not an easy task.
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A temperature gradient describes the changes in temperature at a particular location. In geophysics, it is usually measured in degrees 
Celsius per vertical kilometer (°C/km).
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Technical potential represents all projects which could be implemented globally, if all geothermal resources could be found and utilized. 
The economic potential refers to those projects that would be economically and financially viable.