Sodium-Ion Batteries Reach the US Grid as Peak Energy and RWE Launch First Pilot on the MISO Network
Peak Energy and RWE Americas have deployed the first sodium-ion battery system on the MISO grid in Wisconsin, marking a milestone for the cheaper, cobalt-free chemistry in the US.
Overview
Sodium-ion battery manufacturer Peak Energy and global energy company RWE Americas have begun piloting a sodium-ion battery storage system on the Midcontinent Independent System Operator (MISO) grid in eastern Wisconsin, marking the first deployment of the chemistry on one of North America’s largest interconnected power networks. The project uses Peak Energy’s GS1.1 system, which requires no active cooling and operates across a wide temperature range, according to Electrek. The pilot arrives as sodium-ion technology transitions from laboratory curiosity to commercial product, driven by its reliance on abundant, inexpensive materials instead of lithium, cobalt, or nickel.
What We Know
Peak Energy’s sodium-ion system is designed to reduce lifetime energy storage costs by roughly $70 per kilowatt-hour, approximately half the cost of conventional lithium-ion battery systems, as reported by Electrek. An analysis by Aurora Energy Research found that installing 10 gigawatt-hours of battery capacity across the MISO region over the next decade could lower total system costs by $27 billion, with sodium-ion reducing those storage costs by more than 25 percent compared to lithium-ion alternatives. Peak Energy CEO Landon Mossburg stated that sodium-ion innovations “greatly reduce energy storage costs” and described energy storage as “central to providing dispatchable, reliable energy on demand.”
RWE Americas, which operates 13 gigawatts of generation capacity across the United States, is partnering on the pilot as the MISO region faces surging electricity demand and limited grid-scale storage options. Grid batteries are becoming increasingly critical as wind and solar capacity grows, providing dispatchable power during demand spikes that intermittent renewables cannot reliably cover.
The Wisconsin deployment is part of a broader global push toward sodium-ion commercialization. CATL, the world’s largest battery manufacturer, confirmed plans to deploy its Naxtra sodium-ion battery line at commercial scale across multiple sectors in 2026, including energy storage, battery swap stations, and passenger vehicles, according to Batteries News. CATL’s second-generation sodium-ion cells achieve an energy density of 175 watt-hours per kilogram, comparable to lithium iron phosphate batteries, and have passed China’s national safety standard for electric vehicle traction batteries. The company plans to deploy more than 3,000 battery swap stations across 140 Chinese cities by the end of the year.
Separately, researchers at the University of Surrey have demonstrated that retaining water molecules inside sodium vanadium oxide cathodes, rather than removing them through conventional heat treatment, nearly doubles the charge storage capacity of the material. The hydrated cathode maintained stability for over 400 charge cycles and charged at faster rates than conventional versions, according to ScienceDaily. Lead researcher Daniel Commandeur described the results as “completely unexpected,” noting that the traditional assumption had been that water caused problems in these structures.
What We Don’t Know
The Wisconsin pilot is small-scale, and Peak Energy has not disclosed the exact capacity of the deployed system or a timeline for scaling to larger installations. Whether the GS1.1 system’s performance characteristics hold across seasonal temperature swings in the upper Midwest remains to be demonstrated over a full operating cycle.
Sodium-ion batteries still lag behind lithium-ion in energy density, which limits their use in applications where weight and volume are constrained, such as passenger vehicles with long-range requirements. CATL’s 175 Wh/kg figure matches lithium iron phosphate but falls short of the 250-plus Wh/kg achieved by nickel-rich lithium-ion chemistries used in premium electric vehicles.
The cost advantage of sodium-ion is well established in principle, given that sodium is one of the most abundant elements on Earth, but real-world manufacturing costs at scale have yet to be verified by independent analysts. China currently dominates sodium-ion production capacity, and whether Western manufacturers can achieve cost parity without the same supply chain infrastructure is an open question.
Looking Ahead
The convergence of a US grid pilot, CATL’s mass production ramp, and new cathode research suggests that 2026 may be the year sodium-ion batteries transition from a promising alternative to a deployed grid technology. The MISO pilot will provide the first real-world performance data for sodium-ion on a major US grid, while CATL’s multi-sector rollout will test whether the chemistry can scale beyond stationary storage into transportation. If the cost and performance claims hold, sodium-ion could reshape the economics of grid-scale energy storage by reducing reliance on lithium supply chains that remain concentrated in a handful of countries.