Long-Duration Energy Storage

Iron-Air Battery

Iron–air batteries promise affordable, multi-day energy storage for the grid by harnessing abundant, eco-friendly iron, but face challenges with efficiency and material durability at scale. Ongoing innovations in materials and system design aim to unlock their potential as a safe, sustainable solution for firming renewables and boosting grid resilience.

Vanadium Redox Flow Battery

Vanadium redox flow batteries (VRFBs) are a unique energy storage technology that stores power in liquid vanadium electrolytes, allowing independent scaling of power and energy for cost-effective, long-duration storage. With lifespans exceeding 20,000 cycles and virtually no capacity loss, VRFBs are gaining traction worldwide—especially in China—despite higher upfront costs, thanks to their robust performance and recoverable electrolyte value.

Refractory Brick Heat Battery

From ancient kilns to cutting-edge grid-scale solutions, Thermal Energy Storage systems are revolutionizing industrial decarbonization and renewable energy integration with high-temperature, low-cost, and modular technologies that surpass conventional batteries. As innovations drive material sustainability and system flexibility, overcoming technical and market barriers will be key to unlocking TES’s full potential for deep decarbonization and grid resilience.

Geopressured geothermal storage

Geopressured geothermal storage (GGS) is a breakthrough energy technology that stores and dispatches electricity by harnessing the immense pressure of deep underground rock, offering grid-scale storage without the geographic limits of traditional hydropower. With commercial deployments already underway, GGS delivers high efficiency, low fluid loss, and cost-competitive power, positioning it as a game-changer for renewable energy integration and grid resilience.

Liquid Air Energy Storage

Liquid air energy storage (LAES) is a cutting-edge, long-duration energy storage technology that turns ambient air into liquid at -196°C, storing it for later use to generate electricity with no reliance on lithium or rare-earth materials. With commercial-scale projects underway in the UK, China, and Japan, LAES offers a high-density, geographically flexible alternative to traditional storage methods, boasting a 30–50 year design life and efficiencies up to 90% in hybrid systems.

Compressed Air Energy Storage

Compressed Air Energy Storage has transformed from basic mechanical applications to cutting-edge systems like adiabatic and isothermal CAES, which boost efficiency and eliminate fossil fuel use by capturing and reusing compression heat. Despite innovations in storage architecture and media, CAES must overcome high costs, geological constraints, and regulatory hurdles to realize its potential as a scalable, zero-emission solution for long-duration energy storage.

Solid Oxide Fuel Cell

Solid oxide fuel cells (SOFCs) are high-efficiency, fuel-flexible electrochemical devices that generate electricity directly from a variety of gaseous fuels at elevated temperatures, offering a promising pathway for clean power and hydrogen production. Despite rapid market growth and major deployments by companies like Bloom Energy, SOFCs face challenges such as high costs, durability issues, and the need for advanced materials to achieve long-term reliability.

CO2 Battery

CO₂ Batteries are a breakthrough long-duration energy storage technology that stores electricity by compressing and liquefying carbon dioxide, achieving higher energy density than air-based systems using only standard industrial components. Pioneered by Energy Dome, these batteries offer a scalable, lithium-free solution deployable anywhere, with commercial plants already operating in Italy and the U.S.