Sustainable Rural Development: Solar/Biomass Hybrid Renewable Energy System

摘要

This paper describes results from our effort to develop affordable technologies for sustainable rural development, particularly in regions that are plagued with energy poverty and where potable water is inaccessible. A hybrid renewable energy system (HRES) comprising photovoltaic array, battery, and biomass-fueled generator with gasifier, was developed. The system utilizes multiple conversion devices such that when combined, the weakness inherent in either is mitigated. Photovoltaic arrays serve the daytime energy need on days with high insolation, while excess energy is stored in a lead-acid battery. A 12kW_(el) Prakash electric generator serves as the backup power, producing electricity and exhaust heat. This engine derives its fuel from a 50kWth Ankur downdraft gasifier that processes biomass feedstock to yield producer gas. Waste heat from the biomass fueled electric generator serves as thermal energy input to a Scarab AB air gap membrane distillation (AGMD) system. The AGMD module utilizes low-grade thermal energy applied to a salt-water solution also known as feed water, via a heat exchanger. This feed water of a known salt concentration is pumped into the hot inlet of the AGMD module, while the cold side of the membrane distillation module is maintained at a lower temperature using a heat sink. A cross-flow of the hot feed water and coolant water over a semi-porous membrane in the AGMD module results in a vapor pressure driven distillation of saltwater, which yields pure water. Result of the combined HRES and AGMD is a simultaneous production of electricity and pure water, also known as co-generation, which meets the need of a rural population. HOMER software was employed to analyze several configurations of the HRES, ensuring a reliable electricity production and an optimum sizing of the system. The overall result is an optimum levelized cost of energy (LCOE) of the system that falls below the population's ability to pay, making electricity affordable, while also providing portable water for the rural community. The findings from this study suggest that co-generation using HRES and AGMD provides an affordable and reliable energy and water services that meet the needs of a rural community, thus a viable option for sustainable rural development.