Energy storage systems (ESS) currently impact the power grid market by lowering the cost for utilities and businesses to deliver reliable energy to customers. However, new ESS technologies are emerging that could deliver those savings while addressing ongoing environmental issues with the conventional lithium-ion(Li) based storage architectures. While some say Li-based energy storage has already won, utility and business leaders sensitive to long term costs of ownership need to consider more sustainable ESS technologies.
Global supply chain constraints and rare earth mineral supply vulnerabilities challenge even the largest suppliers of Li-based storage technologies. Moreover, end of life toxicity is a growing concern for both businesses and utilities who do not want to carry the liability of disposing of end of life Li ESS on their books. Finally, as severe climate change events become more frequent, Li-based storage presents new risks for utilities and businesses. What liabilities exist when Li storage assets are subjected to a category five hurricane, a magnitude 7.0 earthquake or a raging forest fire?
Fortunately, new energy storage technologies provide alternatives to Li-based storage. Among these, three in particular show promise: zinc-air, sodium-ion and scalable gravity-based storage. All three are considerably less toxic, do not require rare earth minerals, and in many ways are safer than Li-based storage, albeit with some crucial differences.
Zinc-air offers another alternative to Li ESS. This new technology deploys solar power to separate zinc oxide into zinc and oxygen, whereby the zinc stores power until it is recombined with oxygen to generate electricity. This rechargeable system stores deep discharge capable power for a few days and can replicate the process thousands of times. The system can be built for about $100 kWh and is ideal for remote areas where microgrid power is needed. NantEnergy, a pioneer of this technology, offers a low risk modular turn-key package for business or utilities that includes financing, monitoring and control, and an industry-leading performance guarantee. Typically, NantEnergy combines Li with zinc-air in a hybrid ESS design to maximize short, medium, and long term power needs more efficiently and at a lower cost than Li alone. Such hybrid systems eliminate the need for a fossil-fuel generator backup system.
Sodium-ion ESS is an exciting cost-effective alternative for homeowners and businesses. These sodium-ion-based systems use neither toxic materials nor any rare earth minerals. Sodium-ion ESS provides the ultimate in safety and recyclability through its non-toxic, non-flammable, non-corrosive, and non-explosive architecture. A new leader in sodium-ion ESS is BlueSky Energy of Austria which has delivered reliable solutions for the last eight years. Under rigorous testing, BlueSky Energy’s Aqueous Ion Exchange Battery (AIB) system delivered 10,000 cycles at 88.5% efficiency. The AIB module operates in a significantly wider temperature range (23°F – 122°F) than Li-based systems, over decades, with little maintenance required. Key applications for the AIB system include residential, off-grid, microgrid, or commercial installations.
For utility-scale applications, traditional gravity-based storage works by pumping water uphill where it can be stored in a reservoir. The limitation with traditional gravity storage is its requirement on co-locating next to existing hydroelectric facilities. A new gravity-based storage technology by Energy Vault overcomes these challenges by lifting and stacking concrete blocks into towers to store energy. Energy is then released when the blocks are lowered. Because most of the useable utility-scale sites near dams have already been acquired, a scalable, gravity-based ESS that can be deployed anywhere is particularly attractive. This new scalable gravity system uses local materials to fabricate the concrete blocks on-site, reducing cost and significantly increasing speed to market. Energy Vault has developed proprietary technology for block fabrication and machine learning controls for lifting and releasing their blocks. These innovations attracted a $110M investment from Japanese financial powerhouse Soft-Bank. While questions of scalability have been raised, Energy Vault systems can be delivered for less than half the upfront cost of conventional Li storage. Unlike Li-based systems, the capacity of gravity-based systems does not degrade over time.
Innovative solutions by NantEnergy (zinc-air), BlueSky (sodium-ion), and Energy Vault (scalable gravity) offer compelling cradle-to-cradle advantages over traditional Li-based architecture.