Optimum design and scheduling strategy of an off-grid hybrid photovoltaic-wind-diesel system with an electrochemical, mechanical, chemical and thermal energy storage systems: A comparative scrutiny

The global need for electricity generation is rising steadily, making the adoption of hybrid systems a crucial solution. These systems are employed to provide power across various regions, addressing the intermittent nature of solar and wind resources. By integrating two or more green energy sources, hybrid systems require a techno-economic and environmental evaluation of different configurations to ensure the efficient use of renewable energy resources. This study provides an in-depth techno-economic and environmental analysis of hybrid PV/Wind/Diesel systems incorporating battery energy storage (BES), fuel cell storage (FCS), pumped-hydro energy storage (HES), and thermal energy storage (TES) units in comparison to a diesel-only system in Kousseri, Cameroon. The optimization process were conducted for twelve different hybrid systems. These systems include combinations of photovoltaic (PV) panels, wind turbines, diesel generator, TES, HES, BES and FCS. The objective was to identify the optimal sizes of components for each system configuration that can effectively meet the electrical load requirements of three distinct activity profiles: small activity (SA), medium activity (MA), and heavy activity (HA) encountered at Kousseri. The optimal configuration of components for each case is established through the optimization criterion of net present cost ( NPC ). To achieve this goal, a cuckoo search optimization algorithm is employed. Subsequently, all twelve optimized hybrid systems, in addition to the diesel-only scenario, are assessed and compared using various metrics including NPC, cost of energy ( COE ), excess energy fraction ( EEF ), renewable energy fraction ( REF ), loss of power supply probability ( LPSP ), and the total annual greenhouse gas emissions generated. The optimisation results show that the PV/Wind/Diesel/TES combination was economically the most viable system with a minimum NPC and COE of 13,942.9 $ and 0.2579 $/kWh for the SA; 20,228.2 $ and 0.2649 $/kWh for the MA; and 32,158.6 $ and 0.2461 $/kWh for the HA. In terms of reliability, the PV/Diesel/TES configuration was found to be the most reliable configuration with a LPSP, REF and EEF of 0.49 %, 16.53 % and 99.08 % for SA, 0.43 %, 16.86 % and 99.11 % for MA, and 0.38 %, 17.41 % and 98.98 % for HA. The PV/Diesel/TES configuration also emerged as the most environmentally friendly hybrid system, demonstrating a significant reduction of 98.44 % for SA, 98.76 % for MA, and 98.79 % for HA in yearly total pollutants emissions compared to the diesel-only system. Overall, the systems with TES options have shown better techno-economic and environmental performance compared with the systems with BES, HES and FCS units.