Techno-economic optimization of a hybrid heliostat-based CSP-hydropower-biopower system under hydro-limited conditions using Harris Hawks optimization

Hydropower-dependent electricity systems are increasingly vulnerable to climate-driven hydrological variability, which threatens supply reliability in water-limited regions. This study evaluates the techno-economic feasibility of hybrid renewable energy systems designed to ensure reliable electricity supply under hydropower constraints. Three configurations are analyzed: hydropower-biopower, hydropower-CSP, and a combined hydropower-CSP-biopower system. Hourly dispatch simulations are conducted under a fixed annual hydropower availability of 696.162 GWh, representing realistic reservoir operation through a monthly energy budget constraint. Results show that all configurations meet the annual demand of 986.065 GWh with zero unmet load (LPSP = 0). In the hydropower-biopower system, a 128.79 MW biopower plant generates 289.903 GWh annually and achieves the lowest LCOE of 0.083 $/kWh while using 7.8% of biomass resources. The hydropower-CSP configuration, with a 132.5 MW solar tower plant, offers a fully renewable solution but yields a higher LCOE of 0.1226 $/kWh. The integrated system, with 23.86 MW CSP and 127.33 MW biopower, achieves an LCOE of 0.0892 $/kWh while reducing biomass use to 6.6%. Overall, hybridization enhances reliability, flexibility, and energy security under hydro-limited conditions.