Power storage using sand and engineered materials as an alternative for existing energy storage technologies

The wider inclusion of solar and other intermittent renewables in the United States (US) energy mix has presented some unique management challenges and opportunities. Given the existing baseload production capacity, when renewable energy is available from solar power plants, and distributed rooftop solar there is an excess power that is hard to manage with just dispatchable generation. However, there are several environmental and ecological advantages to using these intermittent renewables that will incentivize their wider adoption. Large-scale energy storage offers an attractive additional tool to manage the grid system. In this discussion paper, we propose and theoretically discuss the efficacy of using manufactured sand or other engineered material (e.g., scrap metal) for developing such energy storage solutions. These proposed storage systems convert excess electricity into potential energy by lifting the bulk material and producing electricity similar to a hydropower power plant. These systems may be placed in existing natural or man-made depressions (e.g., old quarries). Compared to hydroelectric systems, these systems will have lower storage volume requirements and will be more environment-friendly by avoiding many of the problems associated with hydroelectric power generation, particularly those related to non-consumptive water loss. Manufactured sand and the engineered metal ball were studied in this discussion as an alternative for power generation. We estimate that such materials may produce 247 kW and 663 kW respectively, in 4 h of operation utilizing 5 h of electricity from solar excess. Based on theoretical calculations such systems were successful in recovering about 56% of the solar excess that may be utilized throughout the day to enhance the base capacity.