What is geothermal Potential? Extracted from IGA News No. 53, pags. 1…

What is geothermal Potential?
Extracted from IGA News No. 53, pags. 1-3


R. Bertani
International Geothermal Association
Executive Director


1. GEOTHERMAL POTENTIAL
Different authors have performed different estimation of the geothermal potential, both for
electricity generation and the direct uses. The IGA is making a compilation of all the existing data,
in order to establish a "confidence interval" of the minimum-maximum expected potential for the
geothermal exploitation.

The published data are the following:
[A]   Fridleifsson, 1999, quoting Bjornsson, 1998
[B]    Gawell, 1999
[C]    Stefansson, 2000 (2)
[D]    Stefansson, 2002, quoting WEA, 2000
[E]    Cataldi, 1999


Reference [A]:
Useful Accessible Resource Base for electricity production: 12,000 TWh/y. This value should be
compared with present annual production of 44 TWh/y in 1997, and with the forecasting to year
2020 with the present growth rate: 318 TWh/y (with a capacity of 58 GWe)
Useful Accessible Resource Base for direct uses: 600,000 EJ/y. Present value 38 TWh/y in 1997,
forecasting for 2020: 141 TWh/y (thermal capacity 37 GWth).


Reference [B]:
With the present technology the world potential should be between 35 and 72 GW of electric
generation capacity. With enhanced technology (permeability enhancement, drilling improvements)
this range could be 66 and 138 GW.
The present installed value (1998) is around 8 GW. Taking into account the effective availability
factor, the geothermal electricity could reach the 1,089 TWh/y value with the maximum quoted
capacity.


Reference [C]:
The world geothermal potential for electricity generation is about 22,400 TWh/y; the direct uses are
split into two categories: low and high temperature. The first one is >1,400 EJ/y (>392,000 TWh/y),
while the second is four time less: 400 EJ/y (112,000 TWh/y. The present (1996) world electricity
generation is 12,500 TWh/y and the total world energy use is 396 EJ/y (109,880 TWh/y).
Reference [D]:
Present (from WGC2000 data) value for the geothermal energy is 49 TWh/y for electricity (from 8
GW of installed capacity) and 53 TWh/y for direct uses (from 15 GWth of installed capacity).
The geothermal resources suitable for electricity and direct uses are 5,000 EJ/y. If 10% of these
reserves can be economical exploited, this value of 500 EJ/y could be utilized 1/3 for electricity
generation and the remaining for direct uses.
In 1999 the total world energy consumption was 407 EJ/y.


Reference [E]:
The Accessible Resource Base is 140 1024 J; the resources are 5,000 EJ; the reserves are reduced to
500 EJ. Finally the "reserve on land = RoL", which can be economically exploited for all the
geothermal energy utilization are 370 EJ: it is twice the total production of oil in 1996. Of this RoL
2/3 can be accounted for low temperature (560,000       >2,000
 Potential [D]                   5,900      42,000     150     28,000        98,000         350
 Potential [E]                     46         330      1.2       190          670           2.4


The range of electrical and direct uses potential can be from the following table (rounded values):


                                               Electricity
                         today   Extrapolation to year 2020     Minimum      Maximum
             TWh/y        50                  300                 1,000        40,000
                 GW       8                    40                  140          6,000
                                              Direct Uses
                         today   Extrapolation to year 2020     Minimum      Maximum
             TWh/y        50                140/700              100,000    170,000,000
              GWth        15                 40/200               30,000     50,000,000
3. REFERENCES

BJORNSSON, J., The potential role of geothermal energy and hydro power in the world energy
scenario in year 2020. Proceedings of the 17th WEC Congress, 1998.

CATALDI, R., Geothermal energy development in Europe to year 2020: prospects or hopes?
Technica Poszukiwan Geologiczncyhc, 4-5, 1999, 48-59.

DICKSON, M.H. and FANELLI M., What is geothermal energy? IGA Website, 2002


FRIDLEIFSSON, I.B., Worldwide prospects for geothermal energy in the 21st century. Technica
Poszukiwan Geologiczncyhc, 4-5, 1999, 28-34.

FRIDLEIFSSON, I.B., Geothermal energy for the benefit of the people. Renewable and Sustainable
Energy Reviews, 5, 2001,299-312.


GAWELL, K., REED, M. and WRIGHT, P.M., Geothermal energy: the potential for clean power
from the earth, GEA Website, 1999


MUFFLER, P. and CATALDI, R., Methods for regional assessment of geothermal resources,
Geothermics , 7, 1978, 53--89.


STEFANSSON, V., The renewability of geothermal energy. Proc. World Geothermal Energy,
Japan, 2000.


STEFANSSON, V., (2) Competitive status of geothermal energy. Proc. World Geothermal Energy,
Japan, 2000.


STEFANSSON, V., Global perspective on geothermal energy. Submitted to IEEE, 2002.


WEA 2000: World Energy Assessment: energy and challenge of sustainability. Ed. J.
GOLDEMBERG, UNDP, UNDECOSOC, WEC, 2000


WRIGHT, P.M., The sustainability of production from geothermal resources, Bull. Geo-Heat
Center, 19, 2, 1998, 9-12.