US Startup Brings Diesel-Killing Energy Storage System To Earth

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The US renewable energy transition is forging ahead regardless of the hot mess that passes for federal policy nowadays, and long duration energy storage is poised to play a key role. That means long, as very long. In the latest development, the California startup Noon Energy has just successfully demonstrated a compact system that discharges stored-up solar power for more than 100 hours at a time, far surpassing the 2-10 hour window occupied by conventional lithium-ion batteries.

The Return Of The Solid Oxide Fuel Cell

If you’re thinking an electrolysis system is in play, that is correct. Electrolysis systems are familiar ground here at CleanTechnica, mainly for their use in “splitting” water to produce hydrogen and oxygen. Noon’s foundational technology is similar, but different. Instead of using water as an input, Noon has developed a reversible solid oxide fuel cell that deploys renewable electricity to split carbon dioxide into oxygen and solid carbon. The carbon serves as the energy storage medium, and the oxygen is vented to the air. When electricity is needed, the system draws oxygen from the air to re-convert the stored energy.

Solid oxide fuel cell technology has been lingering in the background of the clean tech field and it rarely surfaces on the CleanTechnica radar. However, an uptick in investor activity has been stirring, and a new report by the firm Research and Markets indicates that more is on the way.

Noon also calls its system a “reversible electrofuels battery.” The company is playing the details close to the vest, except to note that it relies on a minimal amount of critical materials, totaling less than 1% of the amount needed for lithium-ion batteries.

The Mars Connection

A recent mission to Mars provides some additional clues. A solid oxide electrolysis system was featured in the “MOXIE (Mars Oxygen In-Situ Resource Utilization Experiment) that rode along to Mars on the 2020 rover mission. As the title of the project suggests, MOXIE was sponsored by NASA’s Human Exploration and Operations Mission Directorate and Space Technology Mission Directorate with the aim of producing oxygen from the atmosphere on Mars.

“Mars atmosphere enters the system through an inlet valve and dust is filtered out. A scroll pump delivers up to 50 g/hour of atmosphere to the SOXE subsystem,” NASA explains, with a scroll pump being a type of compressor system and SOXE being short for solid oxide electrolysis.

“The Mars atmosphere is processed as follows: the SOXE is warmed to 800 C; the pump is started and the filtered air will flow continuously at >1 torr to the SOXE. The O2 and CO are separated and the flow rate is measured. The O2 and CO are vented out the side of the rover,” NASA elaborates.

A 2022 review of the MOXIE project in the journal Science Advances provides more detail, noting that CO2 from the Mars atmosphere flows over a nickel-based catalyzed cathode within the SOXE assembly, where it decomposes into oxygen ions and CO.

“The scandia-stabilized zirconia ceramic electrolyte selectively passes oxygen ions to the anode, where the ions recombine into O2, which is measured for quantity and purity before being released to the Mars atmosphere,” the review team noted. “The cathode exhaust is a mixture of CO2, CO, and inert atmospheric gases, primarily argon and nitrogen.”

Follow The Money

Here on Earth, Noon has worked long and hard to prep solid oxide electrolysis for the commercial energy storage market. The startup launched in 2018 and soon caught the eye of the ARPA-E funding office in the US Department of Energy, which provided the company with an award of $500,000.

“Noon will create a rechargeable battery that turns solar and wind electricity into on-demand power. The battery uses ultra-low-cost storage media and stores energy by splitting CO2 into solid carbon and oxygen,” ARPA-E explained.

By 2020 Noon was also working on a fellowship with the Cyclotron Road program for entrepreneurial scientists at Lawrence Berkeley National Laboratory in California, where the company assembled its first bench-scale prototype. The program also provided Noon with an opportunity to develop a marketing plan with a focus on stationary energy storage.

A 2021 recap of the Cyclotron work affirms that Noon’s energy storage media costs “well” below $1.oo per kilowatt-hour capacity, amounting to less than the cost of the system containers. “It also can operate with a high roundtrip energy efficiency of ~80% and has 10x higher energy density than conventional aqueous flow batteries, even higher than lithium ion batteries at system level,” the Cyclotron team added.

“The cost structure indicated profitability right away for the identified initial markets, and the long-term cost would enable grid-scale solar- 3 plus-storage at less than 5 cents per kWh, undercutting conventional fossil-fuel power generation,” they added again for good measure.

By 2021, Noon also earned the support of other funders including a CalSEED grant from the California Energy Commission and New Energy Nexus along with support from the Wallenius Wilhemsen’s Orcelle Award (through the Ocean Exchange), and an additional BRIDGE grant from the California Energy Commission. The company also raised a seed round of private investment totaling $3 million, followed by a $28 million Series A funding round led by Clean Energy Ventures with Aramco Ventures’ Sustainability Fund. Emerson Collective, At One Ventures, Mistletoe, and Doral Energy-Tech Ventures also participated, among others.

Next Steps For Long Duration Energy Storage

In the latest news, on January 21 Noon announced the successful demonstration of its “ultra-long-duration energy storage (ultra-LDES)” at scale, at a solar array in Yolo County, California. The project was supported by an $8.76 million grant from the California Energy Commission.

“The project will demonstrate a reversible carbon dioxide to carbon conversion-based storage system to provide 100 kilowatts / 10 megawatt-hours of LDES combined with an existing solar PV field to provide up to 100 hours of capacity for regional disadvantaged and low-income communities, and energy offsets to critical facilities in Yolo County,” CEC explained upon approving the grant in 2024.

“The reversible solid oxide fuel cell battery is the first fully containerized, modular ultra-LDES system successfully operated for thousands of hours,” Noon affirmed on January 21. Noon also took the opportunity to note that its system is 2-3 times more compact than a conventional battery array, and 20-200 times more compact than flow batteries, pumped hydro, and other long duration options.

For the record, Noon does not advise cutting lithium-ion batteries totally out of the picture. The company indicates that its fuel cell is compatible with capacity management over the course of multiple days, while an integrated lithium-ion battery array handles more immediate tasks.

“Today, most renewable energy is stored in lithium-ion batteries that are sized for 2 to 10 hours. Combining this with a Noon battery, which has 50 times that energy capacity, is the optimal configuration for cost and performance,” Noon emphasizes.

Keep an eye out for Noon’s next project, a commercial-scale system at a location to be announced.

Image: A new compact, containerized energy storage system can store up solar power and deliver it for more than 100 hours at a time, day or night (cropped, courtesy of Noon Energy).