Pumped Storage Hydropower (PSH) is one of the most cost-effective utility-scale options for grid energy storage. The U.S. has plants across the country, totalling over 20GW of capacity. Now the Dept of Energy (DoE) is backing four teams developing blue sky (water?!) ideas that should make the next generation of PSH even cheaper. In this article the National Renewable Energy Laboratory (NREL) tracks their progress so far. They include dams made of steel, tunnel-boring machines for underground PSH, engineering innovations (to reduce tunnel construction times, costs, risks), and 1-10 MW modular “closed-loop” plants (using big water tanks, no need for natural reservoirs). They’re still at the design stage but the DoE’s support is there to reduce commissioning time from 10 years to 5. The cheaper and more flexible PSH becomes the more solar and wind can store its excess generation for a clean energy grid.
What does it take to fast-track pumped-storage hydropower (PSH) projects? Four hard-working teams of innovators may hold the answer.
In October, the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy Water Power Technologies Office awarded each of these four teams up to $500,000 in cash and support as part of the Furthering Advancements to Shorten Time (FAST) Commissioning for Pumped-Storage Hydropower Prize.
With a mission of reducing the time, cost, and risk associated with commissioning pumped-storage hydropower projects, the FAST Prize challenged competitors to cultivate new ideas, designs, and strategies to accelerate PSH development and reduce commissioning time from the current 10 years to less than five.
The following is a rundown of the progress made by the four winning teams four months in.
Steel dams
Team Wittmeyer-Dasgupta of the Southwest Research Institute (SWRI) won for a modular steel concept for dams that reduces costs by one-third and cuts construction schedules in half.
Over the past couple of months, the team has continued to examine hypothetical steel dam designs for the upper reservoir at the Gordon Butte PSH project in Montana.
The team produced designs for steel dams of two different heights—80 feet and 100 feet. They also generated estimates of the total weight of structural steel required for each design, as well as the number of necessary steel supports and face plates.
To accelerate pumped storage hydropower development, SwRI has developed a modern version of a 19th-century steel structural dam to impound water in a reservoir. The circular dam above is composed of modular sections that can be rapidly assembled using redesigned steel support frames made of standard W-beams and S-beams (left). The frame and water-tight faceplate modules are put in place using mobile heavy-lift cranes. / SOURCE: Southwest Research Institute
Team Wittmeyer-Dasgupta is also helping the U.S. Department of Defense achieve its net-zero energy goals by examining the possibility of installing PSH facilities at Holloman Air Force Base in New Mexico and at Fort Bliss Military Reservation in New Mexico and Texas.
Tunnel-boring for underground pumped storage
The Nelson Energy-Midwest Energy Recycling Team won for proposing the use of tunnel-boring machines for underground excavation, which can reduce costs and decrease excavation time by 50%.
In December and early January, the team finalised contracts with the Argonne National Laboratory and the Pacific Northwest National Laboratory (PNNL) to provide support for the ongoing development of the Granite Falls, Minnesota, pumped storage project. Under these agreements, Argonne will evaluate the value of the proposed pumped storage facility to the Minnesota electrical grid, and PNNL will conduct a preliminary evaluation of the use of groundwater for the project.
In December, Doug Spaulding of Nelson Energy presented a webinar on the project in conjunction with the National Hydropower Association Water Innovation Council and DOE.
Reducing excavation times, cost, risk
The JT Livingston Team won for tunnel excavation innovations that will reduce PSH construction times, cost, and risks by up to 50%.
December was a busy month for the team, which continued investigations into tunnelling risk profiles, as knowledge of local geology is critical to both managing risk and maintaining timelines.
The team also completed a demand/supply model for the Public Service of New Mexico (PNM) electrical system, submitting a technical paper in response to a request for information. The team determined that for New Mexico, PSH-anchored, no-carbon generation portfolios would be a substantially lower cost option than the currently proposed carbon-based options.
Currently, the team is working with the Sandia National Laboratories’ Grid Modernization and Resilient Infrastructures Group to validate the 100% no-carbon/lowest-cost scenarios.
10 MW Closed-Loop (no natural water required)
The Eldredge-Medina Team of Liberty University won for presenting a modular, closed-loop, scalable PSH system with a capacity range of 1–10 megawatts that is adaptable to sites without natural bodies of water.
SOURCE: Office of Energy Efficiency and Renewable Energy
The team has been finalising the list of required equipment for physical testing of the system’s water-storage tanks. Once secured, the equipment will be loaned to the Liberty University School of Engineering for conducting physical tests. The team has prepared the site at Liberty University and planned for possible student support for collecting and processing the data.
Additionally, the Eldredge-Medina Team is working on locating and designing a surge tank (or tanks) to balance pressure variations in the system, as well as revising calculations for water hammer, which occurs when a valve suddenly closes in a pipeline and causes a pressure wave to spread.
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This article is published with permission from the National Renewable Energy Laboratory
German grid consumes ~600TWh/a and has a dispatchable generator capacity (fossil, nuclear, biomass) of ~100GW and 110GW wind+solar. Wind+solar is expanding its share in electricity production with >2%/a.
Germany once had pumped storage facilities with a pump/generate capacity of ~6GW and ~40GWh storage.
However, once the Energiewende took steam in past 15years it became clear that those facilities couldn’t earn their low operating costs on the competitive German electricity market.
So all pumped storage construction stopped and an increasing number were mothballed. Now the Fraunhofer ISE graph indicates that only ~2.2GW still operates.
About ~5years ago, I believed that these facilities may become profitable in the 2025-2035 period when wind+solar produce >50% of all electricity. However, I now believe that in near all situations new pumped storage cannot compete against the combination of:
– PtG (Hâ‚‚) with storage in deep earth cavities despite pumped storage better round trip efficiency; 80% vs 50%. The energy amounts which can be stored underground are superior.
– Batteries for the short term.
Still, some existing pumped storage may earn their marginal / operating costs in the 2025-2030 period.