Techno economic viability of hydroelectric energy storage systems for high-rise buildings

Abstract

Intermittent sustainable energy generation in the electrical grid from sources such as solar, hydro, and wind has increased significantly in recent years which for stability purposes has required the concurrent implementation of a wide array of large-scale energy storage solutions like chemical battery and pumped hydro plants. The current study assesses the potential techno-economic viability of two alternative hydroelectric energy storage systems - a building-based pumped hydro system, and a building-based gravity module system. The levelized electricity cost and variable storage cost are used as performance metrics in the study. A numerical model of the proposed systems is developed in Matlab® and analyzed over a number of scenarios in which system capacity and building height are varied. Further comparisons are made with the two following conventional rapidly deployable grid-scale energy generation and/or storage technologies - natural gas peaker plants, and lithium-ion battery plants. This research is unique as no such comparative study has been conducted to date. Results show that the building-based gravity module system is more financially viable and has a greater energy storage capacity than the building-based pumped hydro system in all scenarios considered. The building-based gravity module system can provide energy storage capacities as high as 1358 kWh in buildings that are 300 m tall. Moreover, this system has a lower levelized electricity cost than equivalent lithium-ion battery systems (≤$1.02/kWh) in all buildings that are taller than 156 m. The current study demonstrates that the levelized electricity cost is better suited than the variable storage cost as a metric for gauging the economic viability of grid energy storage systems since system lifetime costs and the time value of money are considered.