As the global energy transition accelerates, the need for reliable, scalable and cost-effective energy storage solutions has never been greater. 

Stationary energy storage technologies broadly fall into three categories: electro-chemical storage, namely batteries, fuel cells and hydrogen storage; electro-mechanical storage, such as compressed air storage, flywheel storage and gravitational storage; and thermal storage, including sensible, latent and thermochemical storage. 

Pumped hydro storage, which falls under gravitational storage, continues to dominate the landscape, accounting for approximately 181GW of project capacity as of 2024, according to Power Technology’s parent company GlobalData. However, the technology entails various challenges, from climate-driven water scarcity to geographic limitations, that constrain its long-term potential. 

Lithium-ion (Li-ion) batteries have also emerged as the most viable storage solution to support renewable energy projects due to their high energy density. However, cost, material constraints and battery degradation rates represent a barrier to long-term, utility-scale applications. 

As such, the power sector is looking beyond traditional storage solutions to diversity, seeking technologies that can be tailored to niche conditions while meeting grid demands. 

Here are ten notable innovations taking place across different energy storage segments, as highlighted in GlobalData’s Emerging Energy Storage Technologies report. 

Electro-chemical storage 

Iron-air and metal-oxide batteries 

US-based Form Energy’s iron-air battery storage solution is reliant on simple materials – iron, water and air – making it more cost effective than lithium-based alternatives. This means that the batteries can be deployed for long-duration energy storage (up to 100 hours), creating resilience during periods of high demand or low renewable generation. 

In August 2024, the company broke ground on its first commercial project, a 1.5MW/150 megawatt-hour (MWh) pilot project in Minnesota, US. 

Meanwhile, another US-based battery manufacturer, Alsym Energy, is seeking to revolutionise the industry with metal-oxide batteries. 

In addition to needing to maximise energy density and minimise degradation rates, batteries for stationary energy storage must be resilient to an increasingly broad spectrum of operating conditions. Overheating and battery fires represent major concerns for safety and reliability. 

Alsym’s metal-oxide battery chemistry relies on non-flammable and non-toxic materials and uses a water-based electrolyte. These properties make the chemistry more resistant to high temperatures, increasing its applicability to urban areas and warmer, high-renewable-potential climates. 

Hydrogen as a chemical energy carrier 

Australian start-up LAVO has developed a patent-pending technology that uses metal hydrides for long-duration, solid-state hydrogen energy storage. 

Hydrogen diffuses into the metal lattice and forms a metal hydride. The hydrogen can then be selectively released with a small temperature increase. The approach allows for high-density energy storage and reduces the risk of hydrogen leakage. 

However, despite its innovative approach, the company is yet to start commercial production. 

Another nascent pathway for large-scale, long-duration energy storage is the use of salt caverns to store hydrogen. 

The viability of salt cavern storage is reliant on underlying geological conditions that allow for hydrogen to be stored without the potential for leakage. 

UK Energy Storage plans to develop this hydrogen storage solution in three areas of the UK – Dorset, East Yorkshire and Cheshire – with the goal of delivering its first project by 2030. 

Electro-mechanical storage 

Gravitational storage 

Swiss company Energy Vault is an active developer of gravitational energy storage solutions, particularly in China. 

The company’s 25MW/100MWh project in Rudong China was successfully connected to the grid in December 2023.  

The project functions by lifting and lowering composite blocks made from local waste concrete and fly ash. Developed near a wind farm and the national grid, it will be charged with wind energy and supply the grid in times of high demand. 

With a storage duration of four hours and an efficiency of up to 80%, the project demonstrates gravitational storage’s potential as a complementary technology that can be quickly discharged with minimal degradation rates compared to other methods such as batteries.  

The project is estimated to have a lifetime of up to 35 years. 

Energy Vault is also constructing a 17MW/68MWh project in Zhangye, China. 

High-density pumped hydro storage 

UK start-up RheEnergise is making strides towards increasing the applicability and performance of pumped hydro storage through its High-Density Hydro technology. 

In April 2024, the company announced its 500kW closed-loop demonstration facility at a mining site near Plymouth, UK. 

The technology uses a fluid known as R-19, which is 2.5-times denser than water, allowing for smaller projects for the same energy storage capacity and providing valuable cost savings. 

Similar to conventional pumped hydro storage projects, the pilot will provide long-duration energy storage. 

Although the demonstrator is the first of its kind and still under construction, RheEnergise’s solution tackles some of the geographical limitations of scaling pumped hydro energy storage. 

Compressed air energy storage 

The Xinyang CAES project is a 300MW/1200MWh compressed air energy storage project that will use an artificial cavern to hold an air storage capacity of 318,000m³. 

The project is budgeted to cost approximately $300m (2.15bn yuan) and has received backing from a coalition of Chinese state-owned enterprises including the Xinyang Construction Investment Group and the Henan subsidiary of China Energy Storage National Engineering Research Centre. 

The project is expected to achieve efficiency of 72% and will hold enough capacity to power more than 300,000 homes. Its relatively high efficiency stems from the use of high-efficiency heat exchangers, which will recover waste heat from the compression and reduce the reliance on external thermal sources for the project’s operational power needs. 

The Xinyang CAES project was announced in February 2025 and is set for completion by the end of 2026. 

Thermal energy storage 

Sensible thermal energy storage 

US start-up Rondo is developing an “electrified thermal energy storage” solution that uses a combination of renewable energy and electric heaters to heat a large quantity of bricks. 

The electric heaters function at almost 100% efficiency to heat the bricks up to 1,500°C. The thermal energy drives turbines to provide a continuous source of heat and power for industrial facilities. 

An advantage of the solution is its simple and durable design, with an unlimited number of charge cycles and lifetimes of up to 40 years. 

The company’s solution is already in operation in an industrial park in Skive, Denmark, where recovered heat, combined with renewable energy, is used to power biogas production. 

Building on the country’s growing interest in thermal storage, Denmark-based Hyme Energy is also pursuing innovations in sensible thermal energy storage by relying on molten salts to capitalise on excess renewable generation.  

Hyme’s system is charged during periods of high renewable generation, and the renewable electricity is then used to heat molten hydroxides up to temperatures of approximately 600°C. When renewable generation falls, the stored energy is used to convert water into steam, which is used to drive turbines and generate power.  

The technology offers a lifetime of up to 20 years and a continuous discharge duration of 24 hours, providing a buffer against diurnal variations in renewable generation.  

Hyme’s solution targets both industrial facilities that are seeking to decarbonise using renewable generation and residential heating.  

The company collaborated with Sulzer to inaugurate a pilot project in April 2024 in Esbjerg, Denmark. The project uses molten salt technology in combination with heat exchangers and advanced pumps. 

Latent thermal energy storage 

Italian start-up Energy Dome has developed a “carbon battery” that relies on thermo-mechanical cycling to shift carbon dioxide (CO₂) between its gaseous and liquid phase. 

In Energy Dome’s process, the CO₂ is drawn from its Dome ‘gasholder’ and stored under pressure before evaporating and expanding gas through a turbine, generating electricity. 

The solution offers several benefits compared with the dominant Li-ion batteries, including minimal degradation, project lifetimes of more than 30 years, relatively simple material requirements and off-the-shelf components. 

The company has experienced increased interest within the power sector, with utility Engie SA signing an offtake agreement for Energy Dome’s first full-scale battery in Italy, due to be commissioned in 2025. The project is supported by the EU-Catalyst Partnership, which includes support from the European Commission and the European Investment Bank, among others.