| Abstract |
In the present work we report updated assessment of geothermal resources of Brazil, based on results of geothermal data obtained at over 1100 sites and hydrothermal and energy use data on thermal fluid discharge systems at over 110 localities. The total resource base, referred to the accessible depth limit of 3km, is estimated at 1800 TJ. This is nearly 25% less than previous calculations, as it allows for cooling effects of regional scale groundwater circulation in deep sedimentary strata. Results of recent geothermal surveys carried out in the states of Tocantins, Pará and Mato Grosso in Brazil have contributed to the discovery of a significant low temperature geothermal anomaly in the eastern part of the state of Tocantins. However, the potential for high temperature geothermal systems appears to be restricted to the Atlantic islands of Fernando de Noronha and Trindade. The part of recoverable resources, calculated on the basis of regionally averaged values of porosity and permeability, is estimated to be of the order of 4 TJ, but only a small fraction of it is being currently exploited. The total capacity of low temperature geothermal systems under economic exploitation is estimated at 365 MWt, while the annual energy use is estimated to be of the order of 6540 TJ. About a dozen of the spring systems account for the bulk of this capacity. Most of them are located in west central Brazil (in the states of Goiás and Mato Grosso) and in the south (in the state of Santa Catarina). The potential for large scale exploitation of low temperature geothermal water for industrial use and space heating is considered to be significant in the central parts of the Paraná basin (situated at southern and southeastern Brazil), where cold winter seasons prevail under subtropical climate conditions. |