Techno-economic analysis of viability of two stand-alone water pumping systems for rural areas of Kanem oasis: Case studies of solar photovoltaic (PV) and solar organic Rankine cycle (ORC) systems

Abstract

• Water pumping by autonomous systems saves 0.08 $USD/kWh for the ORC system and 0.07 $USD/kWh for the PV system compared to diesel. • Cash flow and cumulative NPV are higher during the operation of the ORC system for water pumping compared to the PV system. • The ORC fluid R134a is recommended for ORC pumping systems due to its superior performance. • ORC pumping systems guarantee profitability only for powers greater than 60 kW; below this value, the PV system is recommended. • The carbon saving is 15,632 kgCO 2 for ORC system and 16,000 kgCO 2 for PV system, the corresponding carbon cost is respectively 10,942 $USD and 11,340 $USD. This study addresses the challenge of providing affordable water through stand-alone systems. The aim is to identify the most cost-effective system in terms of energy and economics. An innovative, multi-criteria approach combining financial and energy analysis is used to achieve this objective. It was found at the first time, that the average stable operating irradiation for both systems was 6500 Wh/m 2 , with a saving energy ratio of 0.0063 for PV and 0.062 for ORC, corresponding to a maximum pumping flow rate of 30 m 3 /h for a geometric head ranging from 50m to 80m. The total surface area covered by the solar field is 206.1 m 2 for PV compared to 200 m 2 for the ORC system operating with R134a. Economic analysis revealed that PV has a LCOE of 0.308 $USD/kWh compared to 0.017 $USD/kWh for the ORC, corresponding to NPV of 6573.1 $USD and 12068 $USD, respectively, for all organic fluids chosen in the ORC system. Furthermore, under the same operational conditions, PV has a Payback Period (PBP) of 2.3 years compared to 3.5 years for the ORC. Water pumping by autonomous systems saves 0.08 $USD/kWh for the ORC system and 0.07 $USD/kWh for the PV. The carbon saving is 15632 kgCO 2 for ORC system and 16000 kgCO 2 for PV system, the corresponding carbon cost is respectively 10942 $USD and 11340 $USD. The multi-criteria sensitivity analysis showed that the ORC system is more profitable than the PV system at higher geometric heights. Even during low sunshine periods, the ORC maintains stable power production. These results demonstrate that the ORC is versatile and suitable for applications like water pumping, offering a strong alternative to mature and efficient PV systems. This finding contribute advances knowledge on ORC sustainability and applications.