Hybridisation of geothermal source with ORC-based load loop for uninterrupted generation of steady power

Abstract

The dynamic performance of a hybrid power plant configuration comprising of a ground heat exchanger and an organic Rankine cycle (ORC) for power generation at the load end is studied. The ground heat exchanger, reservoir, boiler and ORC heat exchanger are modelled using simplified energy equations-based reduced-order models. The developed numerical models are validated against the results obtained from published literature, and agreeable accordance is found in the simulated trends. The simulations are performed to illustrate the advantage of using insulation in the ground heat exchanger. The time required for the stabilisation of outlet temperature in a borehole heat exchanger (BHE) is estimated from the computational results. The simulation of dynamic characteristics demonstrates that the proposed geothermal-ORC hybrid system is capable of producing a steady power output of approximately 86.3 kWt. The exergy efficiency of U-shaped BHE without insulation is found to be the maximum.

Keywords

• geothermal
• ground heat exchanger
• borehole heat exchanger
• renewable energy