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

The Largest geothermal Fields of the world
Table 1.5 shows that the world’s largest geothermal fields (in terms of installed power generation) are 
located in North and Central America, Italy, and Southeast-Asia.
T A B L E 1 . 5
Geothermal Sites Generating Over 3,000 GWh/a (2010) 
COUNTRy
NAME OF FIELD
ENERGy GWh
CAPACITy INSTALLED MW
United States
The Geysers
7,062
1,595
Mexico
Cierro Prieto
5,176
720
Philippines
Tongonan
4,746
716
Italy
Lardarello
3,666
595
Indonesia (Java)
Salak
3,024
377
Source | Based on Bertani 2010.
FuTurE uTILIzATION SCENArIOS
Both the theoretical potential and the technical potential for geothermal power generation are very 
large. However, for policy and investment decisions, it is the economic potential that matters: that part 
of the technical resource base that could be extracted economically in a competitive market setting 
at some specified time in the future. Over the short to medium term, the economic potential consists 
of sites that are known and characterized by drilling or by geochemical, geophysical, and geological 
evidence of a potentially commercially viable geothermal energy source. 
Several experts have provided projections on the future development of geothermal power generation 
from hydrothermal resources. A well known approach originates from Italy (Bertani, 2010) and 
estimates that the globally installed capacity could reach 18 GW in 2015, and about 70 GW in 2050. 
The IEA tends to use the same approach (IEA 2011a). These targets are ambitious because they 
would require the installation of new geothermal power plants at a pace far exceeding the historical 
trend. They include the development of all economically viable projects worldwide, with a significant 
share coming from medium or low temperature development projects with binary power plants.
A more conservative approach, utilizing more modest projections for 2020 and beyond, is used for 
the purposes of this handbook. Based on information on currently planned projects and those that are 

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G e o t h e r m a l H a n d b o o k : P l a n n i n g a n d F i n a n c i n g P o w e r G e n e r a t i o n 
actually under construction, by the year 2020 the worldwide increase in geothermal power generation 
(from hydrothermal resources only) is expected to take place in the following parts of the world: