ESS Tech launches 1.2 MWh sodium-ion battery "building block" system, accelerating non-lithium energy storage deployment.

Introduction

As the global energy transition accelerates, the role of energy storage systems in grid flexibility, renewable energy integration, and critical load support is becoming increasingly prominent. However, the lithium-ion battery-dominated energy storage market faces challenges such as supply chain concentration, thermal runaway risks, and cost volatility. Against this backdrop, non-lithium energy storage technologies are starting to gain more attention. On July 8, 2026, ESS Tech officially launched its modular sodium-ion battery system, the ESS Bridge, with a single module capacity of 1.2 MWh, aimed at providing a safer, more cost-effective alternative for utilities, data centers, and commercial and industrial users.

Industry Background: Surging Energy Storage Demand and the Rise of Non-Lithium Technologies

As of 2026, global energy storage deployment continues to grow at a rapid pace. According to data from the International Energy Agency (IEA), global new energy storage installations exceeded 100 GW in 2025, with lithium-ion batteries dominating. However, the reliance of lithium-ion batteries on critical minerals (lithium, cobalt, nickel) and the numerous fire incidents at energy storage power stations in recent years have driven the industry to actively seek alternative technologies. Sodium-ion batteries, with their abundant raw materials (sodium reserves in the Earth's crust are 400 times those of lithium), good thermal stability (less prone to thermal runaway), and wide operating temperature range, have become one of the most promising candidate technologies. The U.S. Department of Energy (DOE) and several research institutions have identified sodium-ion batteries as a key direction for next-generation energy storage.

Current Developments: ESS Tech's Sodium-Ion "Building Block" System

The ESS Bridge system adopts a "building block" design, with each independent unit providing 1.2 MWh of capacity that can be used in series or parallel. Within a standard 20-foot container, up to 4 units can be accommodated, achieving a total energy storage capacity of 4.8 MWh, comparable to the latest model of the Tesla Megapack. The system supports continuous discharge for 16 hours or longer, making it suitable for long-duration energy storage applications.

ESS Tech previously focused on iron-flow battery technology, capable of providing 8 to 22 hours of storage duration, but commercialization progressed slowly. In April 2026, ESS Tech signed an agreement with Alsym Energy to purchase 8.5 GWh of sodium-ion battery cells and modules, marking its official entry into the short- and medium-duration energy storage market. Since the announcement, ESS Tech said it has secured over $1 billion in early customer opportunities, primarily from data centers and utilities.

Drew Buckley, CEO of ESS Tech, pointed out: "AI workloads are reshaping the demand for energy storage in data centers, and sodium-ion batteries can meet these power needs more effectively than traditional technologies." He emphasized that the ESS Bridge not only meets current market demands but also outperforms lithium-ion solutions in terms of safety and total cost of ownership.

Impact on the Energy System: Safety and Supply Chain ResilienceOne core advantage of sodium-ion batteries is safety. Unlike lithium-ion batteries, sodium-ion batteries do not cause thermal runaway—a chain reaction that leads to catastrophic fires—when overcharged, short-circuited, or physically damaged. In early 2025, a fire at a 300 MW energy storage facility owned by Vistra near Santa Cruz, California, destroyed most of the facility, further highlighting the safety risks of lithium-ion batteries. The stability of sodium-ion batteries allows for the use of simpler air cooling systems, reducing energy consumption and maintenance costs, thereby lowering the total lifecycle cost.

Additionally, the supply chain for sodium-ion batteries is more resilient. China currently controls about 70% of global lithium-ion battery production capacity, while sodium is widely distributed worldwide and abundant in North America. ESS Tech points out that using sodium-ion batteries can reduce reliance on "foreign entities of concern" and mitigate geopolitical risks. This is significant for countries and regions seeking energy independence.

Challenges: Energy Density and Scaling

Despite promising prospects, sodium-ion batteries still face significant challenges. Because the mass of a sodium atom is more than three times that of lithium, the energy density of sodium-ion batteries is generally lower than that of lithium-ion batteries. This means that to provide the same capacity, sodium-ion batteries require larger volume and weight. Additionally, the production scale of sodium-ion batteries is currently much smaller than that of lithium-ion batteries, leading to higher initial costs. ESS Tech and other sodium-ion battery manufacturers need to rapidly scale up production to reduce costs and meet growing demand.

Another sodium-ion battery company, Peak Energy, is also actively positioning itself. In late 2025, Peak Energy announced it would deliver 4.75 GWh of sodium-ion batteries to independent power producer Jupiter Power by 2030; in June 2026, the company entered into a manufacturing and design partnership with General Motors (GM) to support GM's stationary energy storage plans, and plans to build a 4 GWh manufacturing facility in Sacramento, California. These developments indicate that sodium-ion batteries are moving from the laboratory to scaled applications, but they still need time to become mainstream.

Future Outlook: Role of Sodium-Ion Batteries in the Energy Storage Landscape

Looking ahead 5 to 20 years, sodium-ion batteries are expected to capture a significant share of the grid energy storage market, particularly in applications that do not require high energy density but emphasize safety and cost, such as large-scale ground-mounted storage stations, distribution grid peak shaving, and commercial and industrial backup power. The International Energy Agency (IEA) predicts that by 2030, the global installed capacity of sodium-ion batteries could reach tens of gigawatt-hours, becoming an important complement to lithium-ion batteries.

At the same time, lithium-ion battery technology is also evolving, with routes such as solid-state batteries and lithium iron phosphate (LFP) continuously reducing costs and improving safety. Sodium-ion batteries are not meant to completely replace lithium-ion batteries but to form a diversified energy storage ecosystem that meets the needs of different time scales and application scenarios.From an investment perspective, capital is flowing into the sodium-ion battery sector. ESS Tech has secured $1 billion in market validation through early customer opportunities, while Peak Energy has gained support from GM and the U.S. Department of Energy. Green investment institutions are also eyeing this track, as ESG standards demand supply chain transparency and a low carbon footprint, areas where sodium-ion batteries have inherent advantages.

On the policy front, the U.S. Inflation Reduction Act (IRA) offers tax credits for domestic clean energy manufacturing, which could benefit the sodium-ion battery supply chain. The European Union and Japan are also accelerating R&D and demonstration projects for sodium-ion batteries. It is foreseeable that with technological advancements and economies of scale, the cost of sodium-ion batteries will drop rapidly, further enhancing their competitiveness.

Conclusion

ESS Tech's launch of the ESS Bridge sodium-ion battery system marks a significant milestone in the diversification of the energy storage industry. Leveraging its safety, supply chain advantages, and ability to meet emerging load demands like AI data centers, this product injects strong momentum into the development of non-lithium energy storage technologies. Although energy density and production capacity still need breakthroughs, sodium-ion batteries are moving from the periphery to the mainstream and are poised to reshape the global energy storage landscape over the next decade. For grid operators, renewable energy developers, and investors, closely tracking the progress of sodium-ion batteries will be key to seizing energy transition opportunities.