| Abstract |
Assessment of geothermal resources of Brazil have been carried out based on updated evaluation of recent geothermal studies. Results of data acquired at 825 sites were employed for this purpose. The total resource base, referred to accessible depth limit of 3km, is found to be 1,823 TJ. A significant number of low temperature geothermal resources have been identified in the continental area, but the potential for high temperature geothermal systems appears to be restricted to the Atlantic islands of Fernando de Noronha and Trindade. Sites with notable geothermal potential include western parts of the state of Santa Catarina, Caldas Novas (Goiás), southern parts of the State of Tocantins, southeastern region of the State of Minas Gerais and western parts of the State of Pernambuco. These sites are located along a sinuous, approximately north-south trending belt in the central parts of Brazil. The recoverable resources have been calculated based on regionally averaged values of porosity and permeability. It is estimated to be of the order of 10 TJ, but only a small fraction 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 6,500 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 Goias 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. In addition, studies have been carried out on very low geothermal energy, also designated as shallow geothermal energy (SGE),for space conditioning purposes including geothermal heat pump and geothermal air conditioning systems. A total of nine academic studies involving SGE systems has been identified. The first very low temperature geothermal system has been implemented in 1996 in the state of Rio de Janeiro, to supply the heating and cooling need of a house thanks to a geothermal heat pump system. Since then, more than 15 studies have been conducted by universities and companies, showing its technical viability, and two additional plants have been constructed. The largest one is a seawater-geothermal plant constructed in Rio de Janeiro in 2015, supplying the cooling demand of the emblematic “Museum of Tomorrow†and the other one is a geothermal heat pump system implanted in a farm house in the state of Parana. In July 2019, Brazil is totalizing a very low temperature geothermal cooling production of 2.3 MW and a very low temperature geothermal heating production of 0,05 MW. This geothermal production is expected to increase in the coming years regarding the ongoing projects identified as part of this state-of-the-art. Among these projects, four of them are planning the implantation of new SGE plants and one of them is an exhaustive study mapping the potential of the technology in Southern Brazil. |