Study on stand-alone power supply options for an isolated community

There are three inhabited islands in Hong Kong beyond the reach of the utility grid. Currently they are powered by diesel generators with fuel supplied by barge. To reduce dependence on diesel and improve power supply quality, the government is planning to explore locally available renewable energy for power generation on the islands. In this study, several power supply options such as renewable energy and diesel power generation were considered for one remotely located community. A techno-economic analysis and a detailed hourly simulation were performed to find an optimal autonomous system configuration. The results were evaluated in terms of power supply quality, life cycle cost, payback time, and greenhouse gas emission. The effects of load variation on system configuration and cost were also examined. The feasibility study demonstrates that the hybrid solar-wind-diesel-battery system could provide the optimal techno-economic performance, and this scenario was discussed with elaborate analysis. The study also shows that the energy dispatch strategy is very important for a system consisting of two dispatchable sources. Compared to a fully renewable energy system, the introduction of a back-up diesel generator in the hybrid energy system can be a more viable option, even though high diesel fuel cost is needed.