Water Requirements in Deep Geothermal Systems

Abstract

The working fluid in a geothermal system is the medium through which heat is extracted from the sub-surface realm and brought to surface. Access to a working fluid is one of four critical risk areas that need to be addressed when undertaking Geothermal Systems Assessments. Surface water and groundwater are regarded as the most viable supplies of working fluid, although there is scope for the use of water cogenerated from hydrocarbon operations. The use of CO2 as a working fluid has also been suggested, and research into this field continues. Water is a valuable commodity, and it is essential that water access issues be addressed in the early stages of planning a geothermal project. Rainfall in Australia is unevenly distributed, both seasonally and geographically. An outline of the full life cycle water requirements of a deep geothermal energy project is presented. Distinctions are made between Engineered Geothermal Systems and Hot Sedimentary Aquifers.