A study on geothermal electricity systems for Tibet geothermal fields considering thermal performance, economic analysis, and CaCO₃ scaling.

This article focuses on the thermodynamic performance, economic analysis, and calcite (CaCO₃) scaling assessment of seven geothermal electricity production systems—organic Rankine cycle (ORC), dual-stage ORC (DSORC), triple-stage ORC (TSORC), single-flash (SF), double-stage flash (DSF), single-flash ORC (SFORC), and double-stage-flash ORC (DSFORC)—applied to Tibetan geothermal fields. The study finds that TSORC yields the highest net power output, followed by DSFORC and DSORC, with flash systems becoming more suitable as geofluid temperature and dryness increase. Thermoeconomic analysis indicates that ORC-based systems generally have lower electricity production costs and shorter payback periods compared to flash and combined systems. Scaling analysis reveals that calcite precipitation primarily occurs at the wellhead for ORC systems, while flash systems experience additional scaling within system components, with DSF showing the highest scaling rate. A selection map based on geofluid temperature and dryness is provided to guide optimal system choice, and the findings aim to support the design and operation of geothermal power plants in Tibet.