Resource endowments effects on thermal-economic efficiency of ORC-based hybrid solar-geothermal system

Abstract

Implementing a high-efficiency hybrid energy generation system requires to comprehensively analyze the influences of multiple factors on the overall performance, including system layout, design parameters, energy resource endowments. For this purpose, this study developed a thermal-economic model for a 300 kW ORC-based hybrid solar-geothermal power generation system at four sites in China, which represents different solar and geothermal energy resources. The optimal configurations of the hybrid system have been obtained for the minimal levelized cost of energy (LCOE) under a certain annual electricity generation (E). The results show that the solar resources continue to play a dominant role in the proposed hybrid system, especially in optimizing the configuration of the system design parameters for the minimum LCOE. Comparing to the individual solar system, the hybrid power generation system significantly enhances its thermal-economic efficiency across the four selected sites, with a maximum increase of 25.34% in E and a maximum decrease of 16.28% in LCOE. Especially in regions with abundant shallow hydrothermal geothermal reservoirs but average solar resources, utilizing shallow geothermal water to preheat Organic Rankine Cycle (ORC) working fluids is a relatively simple yet efficient application of geothermal energy for power generation, worthy of further promotion and implementation.

Keywords

• Solar energy
• Geothermal energy
• Hybrid solar-geothermal power
• Thermal-economic efficiency
• Optimal parameters
• Sensitivity analysis