C7: Pumped Storage — Contributions to the Energy Transition

Presentations are:

Environmental Impacts of Closed-Loop Pumped Storage Hydropower, presented by Bo Saulsbury, Pacific Northwest National Laboratory

Practical Guide on Variable Speed Pumped Storage Plant Application and Selection, presented by Hans Naeff, Black & Veatch

Details about each presentation and the speakers are below:

Environmental Impacts of Closed-Loop Pumped Storage Hydropower, presented by Bo Saulsbury, Pacific Northwest National Laboratory

Transitioning today’s energy system requires utility-scale energy storage for power generated by renewable resources. . Pumped storage hydropower (PSH) currently provides 97% of utility-scale storage in the U.S., but large increases in storage are still needed to meet net-zero targets. To date, all PSH projects in the U.S. are open-loop, that is, PSH projects that are continuously connected to a naturally flowing water feature, but several dozen closed-loop PSH projects are currently working their way through the regulatory process. Closed-loop PSH is thought to have lower environmental impacts than open-loop, but because no closed-loop projects have been built in the U.S., there are no empirical data on actual impacts.

To address this knowledge gap, we have collected information on environmental impacts and protection, mitigation, and enhancement (PME) measures from nine proposed closed-loop projects in the U.S. assessed in draft (N = 2) and final (N = 7) environmental impact statements (EIS) and conducted interviews with closed-loop PSH licensing participants representing a range of perspectives. Our survey of EIS documents identified impacts in 10 resource categories and mitigations in 20 categories that were similar to impacts and PME measures described by interviewees. We found that closed-loop PSH impacts and PME measures were most emphasized impacts to visual resources, wildlife, and cultural resources. In contrast to open-loop PSH and conventional hydropower, impacts and PME focused on aquatic ecology and other surface water resources were not common. Impacts and PME focused on initial reservoir fill and make-up water are unique to closed-loop PSH because they do not have a continuous connection to their water source, whether surface water or groundwater.

Practical Guide on Variable Speed Pumped Storage Plant Application and Selection, presented by Hans Naeff, Black & Veatch

The Paper will guide interested parties through the different steps in the planning of a variable speed Pumped Storage plant, from System Modeling to intermittent fast changing power Sources integration, to the selection of the variable speed technology to Cost and Space caparisons between technologies.

The integration, dispatch and scheduling of Pumped Storage plants in power grids have been topics of discussions for a long time. For newly plant pumped storage plants, it is essential that the units are designed to fit a given environment in terms of it design, sizing, operational rages, by considering the plants Frequency criteria and the Voltage and Reactive power controls.

The sizing of the unit’s inertia to either absorb or release stored kinetic energy in the rotating M/G rotor and P/T mass hereby responding to sudden generation/load imbalances.

Inputs to the PS system model framework are wind and solar generation data such as minute-to-minute and hourly wind generation oscillation, peak wind and solar fluctuations and the coincidental active power ramps, based on critical frequency conditions (day of week, season, weather conditions etc.

As part of the modeling framework the load analyses by maintaining chronology with wind /solar patterns, and associated frequency and voltage fluctuations with focus on net loads (load net of renewable energy resources) to be met by the PS plant. Inputs to the system Modeling framework are the PS HEPP’s project characteristics, the micro-scale load and wind/solar inputs, the customers or grid operators power system information, and the system frequency requirements. The PS HEPP inputs are site characteristics will require storage volume, storage time, and design head, from which design variables are computed. Output of the system analyses – General output for each frequency solution to meet or exceed following criteria’s: Grid voltage, frequency, active and reactive power and the unit’s Motor-Generator – Pumped-Turbine inertia to verify the inertia requirements. The conveyance system transient stability the penstock inertia, and water staring time requirements.