Analysis of Long-Term Sustainability Challenges & Optimization of Solar Thermal Lemongrass Essential Oil Extraction Systems

Abstract

Solar thermal lemongrass (Cymbopogon flexuosus) essential oil extraction is a potential sustainable livelihood for the Indian rural population. In this work, an extensive review of existing extraction techniques, their performances, fitness to the context, as well as sustainability and efficiency factors has been elaborated. While microwave assisted methods can reduce the extraction time and increase the yield, it is at the cost of added complexity and dependency on electric energy, which can be unfit for communities that experience scarce supply. It is required to measure the performance of the microwave hydrodiffusion and gravity (MHG), and microwave steam diffusion (MSDf) methods with the lemongrass genus to verify their advantage over steam distillation, which in the study’s context remains the favorite. The study has unveiled that four key factors need to be considered for ensuring the sustainability of the livelihood: (a) implementation price, (b) operational price, (c) energy consumption, and (d) extraction time. Essential oil extraction can be optimized by six different categories of efficiency factors: (a) post-harvesting drying, (b) plant rehydration, (c) plant chopping size, (d) water to grass ratio, solid loading or plant packing, (e) temperature, steam heat, pressure and airflow, and (f) microwave power.