Quantitative evaluation of renewable-energy-based remote microgrids: curtailment, load shifting, and reliability

Abstract

Achieving carbon-free electricity for all can be facilitated by setting up small to medium-scale off-grid renewable energy systems (RES); however, the variability of renewable energy sources challenges system reliability. In this paper, we optimize a range of RES configurations considering different combinations of solar, wind, battery and pumped hydro storage for a specific location under diverse flexibility scenarios: one of load shifting (flexibility of power demand by changing consumption patterns by 0–30%), one of small load loss/shedding (0–5%), and one of both. Next, we quantitatively assess the impact of the flexibility options, renewable source and energy storage type impact on the microgrids' optimal energy management, cost, curtailment, and reliability level. The results show that RES utilizes 40–45% of added flexibility during particular day hours. The period of these critical hours is significantly affected by the RES type: namely the morning hours for battery storage-based RES while the evening hours for pumped hydro storage-based RES. The load shifting decreases the RES cost by 4–9%, but it does not reduce the overall system curtailment due to the substantial decrease in the energy storage size compared to the RE generator size when the load deferment is allowed. However, load loss scenarios not only reduced the RES cost by 30–50% but they also lessened the system curtailment by 40–51%. The off-grid RES cost can be reduced up to 60–67% by increasing the system flexibility. Moreover, the type of RE input source substantially impacts the system’ self-sufficiency, energy served to energy generated ratio, and capacity factor, whose values vary in ranging 0.42–0.72, 0.18–0.5, and 0.13–0.23, respectively.