Converting used cooking oils (UCO) and organic waste feedstocks into biodiesel represents a sustainable engineering and environmental pathway toward a circular economy and the decarbonization of the power generation sector. This technology delivers a dual solution: providing environmentally safe disposal of toxic waste oils and organic refuse while yielding a renewable fuel vector that offsets fossil diesel reliance and reinforces grid stability and off-grid generation systems.The primary technical and engineering challenges stem from the high variability of feedstock properties, particularly elevated free fatty acid (FFA) and moisture content, which severely impair transesterification efficiency and trigger soap formation that impedes product separation. In electric power generators, these issues manifest as operational bottlenecks, including higher kinematic viscosity relative to fossil diesel, carbon deposit buildup on fuel injectors, filter clogging, and the degradation of rubber seals and fuel line elastomers due to biodiesel's solvent characteristics. Additional hurdles include lower calorific heating values, elevated cloud and pour points in cold operating environments, and a marginal increase in nitrogen oxide ($NO_x$) emissions during internal combustion.To mitigate these engineering bottlenecks and ensure strict compliance with fuel quality standards (such as ASTM D6751 and EN 14214), researchers and engineers have developed advanced technological solutions. Prominent among these is the implementation of two-stage acid-base catalytic pretreatment, alongside heterogeneous solid catalysts and membrane reactors to strip FFAs and optimize transesterification conversion rates. Furthermore, ultrasound- and microwave-assisted transesterification technologies accelerate reaction kinetics while diminishing process energy demands. To achieve optimal performance in electrical generator engines, biodiesel is typically deployed in standardized blends with petroleum diesel (e.g., B20), combined with antioxidant additives to boost oxidative stability and electronic injection timing recalibration to modulate combustion temperatures, suppress $NO_x$ formation, and preserve engine durability and output efficiency. Al-Mustaqbal University – The First Private University in Iraq