World Geothermal Assessment

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Conference Paper: World Geothermal Assessment

The terrestrial energy current flowing from the mantle to the surface of the Earth is more intense at plate boundaries than within the tectonic plates. At the surface of the Earth, the most obvious manifestations of this energy current are active volcanoes and high temperature geothermal fields. Geothermal assessments have only been carried out for a limited number of countries or regions, while the distribution of active volcanoes in the world is fairly well known. As the volcanoes and the high temperature geothermal fields are manifestations of the same energy current, the distribution of active volcanoes should reflect the geothermal potential of the world. An empirical relation between the number of active volcanoes and the technical potential of high temperature geothermal fields in 8 regions of the world has been established in the paper. This relation is consequently used to estimate the technical potential of high temperature geothermal fields in the world as a whole. The result is that the most likely value for the technical potential of geothermal resources suitable for electricity generation is 240 GWe. Theoretical considerations based on the conditions in Iceland and USA reveal that the magnitude of hidden resources is expected to be 5-10 times larger than the estimate of identified resources. If this is the case for other parts of the world, the upper limit for electricity generation from geothermal resources is in the range 1 – 2 TWe. Furthermore, the frequency distribution of the temperature of geothermal resources in Iceland and USA indicates that the magnitude of low-temperature geothermal resources in the world is about 140 EJ/year of heat. For comparison, the world energy consumption is now about 420 EJ/year. Comparing estimates of the generating capacity for individual geothermal fields obtained on one hand by simulation models and on the other hand by the volumetric method indicates that the volumetric method gives on the average 4 – 5 times higher values than simulation models. Taking the results of the simulation models as an estimate of the lower limit of the geothermal potential, the lower limit of the world geothermal potential for electricity generation is estimated to be about 50 GWe and the corresponding value for direct use to be 1 TWth.

Valgardur Stefansson

World Geothermal Congress; Antalya, Turkey; 2005/04/24

International Geothermal Association, 2005

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Internet link for World Geothermal Assessment

Valgardur Stefansson. 2005. World Geothermal Assessment. In: Proceedings. World Geothermal Congress; 2005/04/24; Antalya, Turkey. Antalya, Turkey: International Geothermal Association; p. 24–29