An Interdisciplinary Approach for Medium-small Size Geothermal Plants Design - A Thermoeconomic Assessment

The sustainability of a geothermal project also deals with economic issues. The feasibility assessment should take into account not only economic, but also thermoeconomic issues, depending on the type of plant. The application of thermoeconomic approach in geothermal energy utilization would lead to the elaboration of production scenarios (power output and extraction rate). This aspect is strictly connected with the possibility of technologic standardization of (for example) ORC geothermal plants. The evaluation of the specific cost of the energy production is not a trivial task, particularly for medium-low temperature resources. An evaluation of the cost items of a plant is presented and the impact of the specific (natural and economic) context is treated. National/Local energy policies, electric grid and market planning are important external factors to determine the specific energy price. Some case studies are analyzed and their technical-economic performances are discussed and compared, through a thermoeconomic assessment. The development of binary cycle geothermal plants market (particularly in Italy) is linked to these issues and discussed under this perspective. The task is to elaborate a methodological interdisciplinary approach (here outlined) for the design decision making processes, being valid only in case of medium-low temperature geothermal resources.