Experimental and Techno-Economic Analysis of Solar-Geothermal Organic Rankine Cycle Technology for Power Generation in Nepal

Abstract

The current research study focuses on the feasibility of stand-alone hybrid solar-geothermal organic Rankine cycle (ORC) technology for power generation from hot springs of Bhurung Tatopani, Myagdi, Nepal. For the study, the temperature of the hot spring was measured on the particular site of the heat source of the hot spring. The measured temperature could be used for operating the ORC system. Temperature of hot spring can also further be increased by adopting the solar collector for rising the temperature. This hybrid type of the system can have a high-temperature heat source which could power more energy from ORC technology. There are various types of organic working fluids available on the market, but R134a and R245fa are environmentally friendly and have low global warming potential candidates. The thermodynamic models have been developed for predicting the performance analysis of the system. The input parameter for the model is the temperature which was measured experimentally. The maximum temperature of the hot spring was found to be 69.7°C. Expander power output, thermal efficiency, heat of evaporation, solar collector area, and hybrid solar ORC system power output and efficiency are the outputs from the developed model. From the simulation, it was found that 1 kg/s of working fluid could produce 17.5 kW and 22.5 kW power output for R134a and R245fa, respectively, when the geothermal source temperature was around 70°C. Later when the hot spring was heated with a solar collector, the power output produced were 25 kW and 30 kW for R134a and R245fa, respectively, when the heat source was 99°C. The study also further determines the cost of electricity generation for the system with working fluids R134a and R245fa to be $0.17/kWh and $0.14/kWh, respectively. The levelised cost of the electricity (LCOE) was $0.38/kWh in order to be highly feasible investment. The payback period for such hybrid system was found to have 7.5 years and 10.5 years for R245fa and R134a, respectively.

Working fluid selection for the geothermal-solar hybrid cycle at Olkaria II power plant in Kenya

“…Among the sources of renewable energy, geothermal has the potential to resolve the energy demand in countries with geothermal reserves. Geothermal energy provides innumerable benefits over other sources of energy since is not affected by climatic variability [ 1 , 2 ]. Considering Africa, Kenya is the leading in geothermal energy with an installed capacity of 863 MW.…”

Energy and Exergy Analysis of an Organic Rankine Cycle used for Ylang-Ylang Essential Oil Distillery Waste Heat Recovery for Power Production in Anjouan Island

“…Moreover, cycle enhancements should be given for turbines, evaporators, condensers and hot water supply respectively. Baral [15] made a techno-economic study of a solar-geothermal hybrid ORC cycle by using R134a and R245fa as organic fluids for system performance, and found that the thermal efficiency of the system changes with the temperature of the heat source : the higher the temperature of the hot source, the greater the thermal efficiency of the cycle.…”

Guideline for electricity generation from hot springs (natural energy storage systems): A techno-enviro-economic assessment

“…These media are commonly used in the direct utilization of geothermal energy for agricultural, swimming pool, and greenhouse purposes [12]. However, the indirect utilization of geothermal energy is implemented for electricity power production [13], like Chena hot springs commercial power plant that generates 210 kW of electricity power with 8.2% thermal efficiency [14]. Thermal springs with temperatures between 21 to 149°C exist in more than 80 countries [15].…”