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A commercial-scale heated sand energy storage pilot project could produce 135 MW of power over five days. The US Department of Energy (DOE) is funding a pilot project to demonstrate commercial viability.
Researchers at the National Renewable Energy Laboratory (NREL) working on a multi-day energy storage system using heated sand have developed a prototype, shown in the featured image above, that has established the bases for a pilot demonstration project.
The sand used in the thermal energy storage (TES) system could be heated up to 1,100 degrees Celsius using low-cost renewable energy. The diagram opposite shows that, when electricity is needed, the system feeds hot sand by gravity into a heat exchanger that heats a working fluid that drives a combined cycle generator.
The NREL teams computer models have shown that a commercial-scale system would retain more than 95% of its heat for at least five days, the national laboratory says in a news release.
DOE will provide $4 million to fund a 10-hour, 100-kW discharge capacity demonstration pilot project scheduled to launch next year at NRELs Flatiron campus just outside from Boulder, Colorado. The pilot project aims to demonstrate the commercial potential of the technology.
On a commercial scale, when the sand is fully heated and stored in five silos, the technology could produce 135 MW of power for five days, according to an NREL report.
According to the report, a levelized storage cost of $0.05/kWh could be achieved in various scenarios.
According to the report, “taking advantage of existing thermal power plants” would facilitate the commercialization of the technology, while other factors that would improve economic profitability “could be payment for capacity by electricity companies, community benefits derived from the retirement of thermal power plants and the continued decline in the price of renewable electricity.” Additionally, “designing the system for dynamic operation (e.g., faster startup, option to add gas) is likely to increase revenue by taking advantage of the daily operation of storage.”
The NREL report said that a technology-to-market transition plan for the TES system had been developed but had not been included in the publicly available report “due to the commercial sensitivity of NREL and its partners.”
Babcock & Wilcox, one of five project team members supporting NREL research, announced in 2021 that it had signed an agreement with NREL, giving it “exclusive rights limited to the field” to negotiate a licensing agreement that would allow the technology to be commercialized.
Several other energy storage technologies have storage durations longer than the typical four-hour limit for battery storage. For example, Hydrostor is developing a 500 MW/4,000 MWh compressed air energy storage project in California. A pumped storage project being developed in Montana would have a capacity of 400 MW and an estimated annual power generation of 1,300 GWh. And flow batteries have a global market estimated by one research firm to be $289 million in 2023.
For seasonal energy storage, hydrogen storage in salt caverns is an option. A project in Utah is expected to have 150 GWh storage capacity combined with an 840 MW gas turbine combined cycle plant capable of producing hydrogen. |
