Exergy-Based Techno-Economic and Environmental Assessment of Pumped Thermal Energy Storage Systems for Sustainable Rural Agriculture

Reliable and sustainable access to energy continues to pose a significant challenge for rural farms in African underprivileged areas, where traditional diesel generators are both economically and environmentally unfeasible. This research explores the potential of pumped thermal energy storage (PTES) systems utilizing a Rankine cycle for the preservation of farm produce, analyzing four configurations of reversible heat pump–organic Rankine cycle (HP–ORC) systems that employ R1234ze(E) as the working fluid: hot-storage cooled HP mode, air-cooled HP mode, basic ORC mode, and ORC mode with integrated electrical heaters. Despite the exploration of hybrid HP–ORC and reversible PTES configurations in the existing literature, there remains a significant lack of research focusing on their feasibility for energy services in rural agriculture, and the literature data remains insufficient for comprehensive decision-making on deployment for small-scale applications in rural settings. To bridge this gap, the thermodynamic performance was evaluated for the PTES configurations through exergy analysis, to measure system irreversibility and component losses. Also, an exergoeconomic assessment was conducted using the Specific Exergy Costing (SPECO) method, while environmental impacts were examined with Eco-Indicator 99, aimed primarily at decision-making for real-life application. The results indicate that the ORC mode with electric heater achieved the highest exergy efficiency at 31.7%, surpassing the hot-storage cooled HP mode by approximately 11 percentage points. The air-cooled ORC with electric heaters exhibited a thermal efficiency of 26.6% and reduced economic losses, while also demonstrating significantly lower environmental degradation compared to the hot-storage HP mode (1327 mpts/s). These results suggest that air-cooled HP-ORC configurations provide an optimal balance of technical, economic, and environmental performance, thereby promoting sustainable, localized energy solutions for rural agricultural practices.