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

Abstract

In this article, thermodynamic performance, economic analysis, and calcite scaling assessment have been completed for each of the investigated geothermal electricity systems for Tibetan geothermal fields. The seven investigated electricity production systems include the 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). A selection map for suitable geothermal electricity production systems has been generated. The DSORC and TSORC can generate 20% more net power output than the SF system under low dryness and medium-low temperature conditions. When the geofluid temperature and dryness increase, flash systems (SF, DSF, SFORC, and DSFORC) have better applicability. In the Yambajan geothermal field, the SF system has the highest electricity production cost ( EPCSF = 0.056 USD/kWh), while the DSORC system has the lowest cost ( EPCDSORC = 0.047 USD/kWh). In the Gulu geothermal field, the DSORC is still the most economical system ( EPCDSORC = 0.022 USD/kWh), but the DSFORC becomes the least cost-effective system ( EPCDSFORC = 0.027 USD/kWh). The scaling associated with using the ORCs (ORC, DSORC, and TSORC) only occurs at the wellhead with a scaling rate of about 2.30 kg/day. In the case of using the flash systems, CaCO3 also precipitates in the system's components; it is found that the scaling rate associated with using the DSF system has a maximum value, which is around 3.864 kg/day. The results obtained in this study are considered useful for the design and operation of geothermal power industries.

A Theoretical Study on the Thermal Performance of an Increasing Pressure Endothermic Cycle for Geothermal Power Generation

“…As the ORC, t-CO 2 , and SF systems have been extensively studied and can be found in many existing references, it is considered that the thermodynamic models of ORC, t-CO 2 , and SF are well known, and so are not elaborated here. In our previous study [36], the models of ORC and Energies 2024, 17, 1031 6 of 24 SF were extensively reviewed and elucidated. The t-CO 2 model was introduced in detail by Guo et al [37].…”

Thermodynamic Analysis of an Increasing-Pressure Endothermic Power Cycle Integrated with Closed-Loop Geothermal Energy Extraction

“…The diagram of the production well and the DHE are illustrated in Figure 3, showing the incorporation of adiabatic material within the thermal insulation layer to ensure effective heat preservation between the inside wall and the outside wall. The models of t-CO 2 , ORC, and SF have been comprehensively reviewed and explained by Yu et al [4] and Guo et al [21], so they are not extensively discussed here.…”

“…As of the end of 2021, the global capacity for power generation from geothermal sources reached 15.85 GW. [4]. According to the World Geothermal Congress 2023 (WGC2023) held in Beijing, China, the world's total installed capacity of geothermal power generation has increased to 16.13 GW in 2022.…”

“…ensure effective heat preservation between the inside wall and the outside wall. The models of t-CO2, ORC, and SF have been comprehensively reviewed and explained by Yu et al[4] and Guo et al[21], so they are not extensively discussed here.…”