TECHNOLOGIES OFFER INCREASING ARRAY OF LONG DURATION ENERGY STORAGE OPTIONS

hours of energy storage to 3CE from Hydrostor’s planned Willow Rock Energy Storage Center that will use the company’s Advanced Compressed Air Energy Storage technology. Hydrostor says the project, when completed, will abate up to 28 million metric tons of carbon dioxide over its lifetime.

Hydrodstor’s technology combines elements of a compressed air storage system with a pumped hydro system. The process stores energy as compressed air but captures and stores the heat of compression for future use. The compressed air is stored in a purpose-built underground cavern that uses a water reservoir to maintain constant pressure. The facility discharges energy by reversing the process, using the stored heat and pressure to power a conventional turbine generator. The system has no performance degradation over its 50-year plus expected lifetime, Hydrostor said.

FWhile lithium-ion technology has been king of the hill when it comes to energy storage options for utilities, this year could prove to be a key inflection point for the emergence of alternative energy storage technologies in the U.S. if recent developments are any indication. or several years, lithium-ion batteries have dominated the energy storage landscape for electric utilities, but one of the limitations of lithium-ion batteries is the limited amount of storage hours they can provide. And there have also been safety concerns raised about fires occurring at lithiumion facilities. There is a wide array of storage technologies that differentiate themselves from lithium ion by offering longer storage durations, which is becoming increasingly important as intermittent renewable energy sources continue to expand across the U.S. power grid. “The value of longduration energy storage, which helps address variability in renewable energy supply across days and seasons, is poised to grow significantly as power systems shift to larger shares of variable generation such as wind and solar,” a report posted on the National Renewable Energy Laboratory notes.

One of the companies making a splash in the iron flow battery space in recent months is ESS Inc. Two California public power utilities, SMUD and Burbank Water and Power, in 2022 announced agreements with ESS. SMUD and ESS on Sept. 20, 2022 announced an agreement to provide up to 200 megawatts (MW)/2 gigawatt-hours (GWh) of long duration energy storage that will be provided by ESS. The agreement calls for ESS to deliver a mix of its long-duration energy storage technology for integration with the SMUD electric grid beginning in 2023. In November, ESS and Burbank Water and Power entered into an agreement for ESS to deliver BWP’s first utility-scale battery storage project. Under the agreement, a 75 kilowatt (kW)/500 kilowatt hour kWh ESS “Energy Warehouse” will be installed and connected to a 265 kW solar array on BWP’s EcoCampus. The iron flow battery will support the increased use of renewable power and allow excess renewable energy to be stored and used as baseload energy for Burbank, improving the resilience and reliability of the grid.

In late January, Form Energy announced that it had entered into definitive agreements with investor-owned Xcel Energy to deploy Form Energy’s iron-air battery systems at two of Xcel Energy’s retiring coal plant sites. Xcel Energy–Minnesota will deploy a 10 MW/1,000 MWh multi-day storage system at the Sherburne County Generating Station in Becker, Minnesota. Xcel Energy–Colorado will deploy a 10 MW/1,000 MWh multi-day storage system at the Comanche Generating Station in Pueblo, Colorado. Both projects are expected to come online as early as 2025 and are subject to regulatory approvals in their respective states. In December, West Virginia Gov. Jim Justice announced that Form Energy will partner with the state of West Virginia to build its first iron-air battery manufacturing facility on 55 acres of property in the northern panhandle of West Virginia, along the Ohio River. Meanwhile, California community choice aggregator Central Coast Community Energy in January said that it signed a 25-year power purchase agreement for a compressed air energy storage project with Hydrostor. The nearly $1 billion power purchase agreement calls for the delivery of 200 megawatts, 1,600-megawatt

Hydrostor said its technology offers the same services as a natural gas plant while having zero emissions because it uses surplus electricity as fuel. The company is targeting high value grid applications such as transmission deferral and fossil fuel generation replacement.

In early January, Energy Vault Holdings, Inc. and California investor-owned utility Pacific Gas and Electric announced the companies are partnering to deploy and operate a utility-scale battery plus green hydrogen long-duration energy storage system with a minimum of 293 megawatt-hours of dispatchable energy. The system is designed to power downtown and the surrounding area of the City of Calistoga, Calif, for a minimum of 48 hours during planned outages and potential Public Safety Power Shutoffs, which is when the powerlines serving the surrounding area must be turned off for safety due to high wildfire risk. PG&E submitted the project contract for review and approval to the California Public Utilities Commission on December 30, 2022, with a request for the issuance of a final resolution approving the project by May 15, 2023. The energy storage system will be owned, operated and maintained by Energy Vault while providing dispatchable power under a long-term tolling agreement with PG&E.

The system’s capacity may be expanded to 700 MWh, which would allow it to operate for longer without refueling, enabling further flexibility for PG&E and the City of Calistoga. Energy Vault’s system will replace the typical, mobile diesel generators used to energize PG&E’s Calistoga microgrid during broader grid outages. Construction is anticipated to begin in the fourth quarter of 2023 with commercial operation expected by the end of second quarter of 2024.Upon completion, this project is expected to be the first-of-its-kind and the largest utility-scale green hydrogen project in the United States.