Hoover Dam's Environmentally Sustainable Energy Storage Solution
The goal of this infrastructure project is to store “hydroelectric energy” during periods of abundant renewable energy production by pumping from the Colorado River to Lake Mead. During periods of high energy demands, power will be generated from this water storage. The pumping cycle would require the construction of new facilities including a Colorado River Intake, Pump Station, Conveyance System (either pipeline or tunnel), and a Reservoir Outlet Structure. Capital costs are estimated to be in the range of $5B to $10B. The team is tasked with developing alternatives for the conveyance system to find the cheapest, most efficient option. After the best option is found and a cohesive environmental study is conducted, the aforementioned new facilities can be designed. Further efforts include performing a sensitivity cost analysis and pipe stress analysis for the optimal design of the conveyance system.
The alternative analysis begins by calculating the flow requirements for the return pump station based on the flow out of the Hoover Dam generation station. The dam is assumed to generate 500MW of power during a 5 hour period. The downstream pump station will return the same flow over a period of 10 hours, which yields a return flow of approximately 9000 cubic feet per second. A preliminary alignment routing allows the static and friction head to be calculated for both a surface pipeline and tunnel, from which the power requirements for the pump can be determined.
Next a cost analysis is performed to determine the optimal alternative and pipe sizing. Using unit cost estimates from Tremblath Consulting, capital and operating costs are estimated over 20, 30, 40, and 50 year periods. The present worth of the costs is calculated and the optimal alternative selected. The tunnel alternative is selected since its operating costs are a fraction of the surface pipeline's, with only marginal increases in capital costs. Since the optimum pipe diameter depends on the time scale analyzed, a sensitivity analysis is in progress to determine the appropriate metric.
Future steps include the structural design of the pump station, conveyance tunnel, and outfall.
