ESS Tech, Alsym Energy partner for 8.5 GWh of non-lithium BESS solutions

<figure class="wp-block-image size-large"><img alt="BESS battery decommissioning" class="wp-image-54175" height="527" src="https://solarbuildermag.com/wp-content/uploads/2025/04/BESS-removed-by-crane-web-700x527.jpg" width="700" /></figure>

<p>Long-duration energy storage system (LDES) manufacturer <a href="https://essinc.com/">ESS Tech Inc.</a> and battery maker <a href="https://www.alsym.com/">Alsym Energy</a> have formed a partnership to add 8.5 GWh of sodium-ion batteries to ESS Tech&#8217;s portfolio.</p>

<p>The agreement signifies a milestone for ESS, as it enters into the short- and medium-duration battery storage market. Historically dominated by lithium-ion products, the entry of ESS and Alsym presents a unique solution for the battery world. Drew Buckle, the CEO of ESS Tech, says Alsym&#8217;s iron flow and sodium-ion batteries are &#8220;complementary technologies&#8221; to one another.</p>

<p>&#8220;ESS&#8217;s existing Energy Base iron flow platform is engineered for the 8–24 hour long-duration segment, where deep daily cycling, 25-year asset life, and zero capacity degradation deliver the lowest levelized cost of storage,&#8221; he says. &#8220;Together, the two chemistries form a unified, non-lithium platform that enables ESS to meet customers&#8217; full storage needs from a single trusted provider, whether the application calls for firming renewables over a few hours, shifting energy across a full day, or pairing both within a single project to optimize economics across the full duration curve.&#8221;</p>

<p>ESS Tech CCO Randall Selesky says the partnership offers &#8220;safer, more sustainable technologies&#8221; to the <a href="https://solarbuildermag.com/energy-storage/home-storage-ai-vpps-obbba-and-other-acronyms-shaping-the-ess-market/">energy storage market</a> at large. Combining Alsym&#8217;s sodium-ion technologies with ESS Tech&#8217;s systems gives customers a pathway to transition out of the lithium-ion market, without having to compromise on price or performance.</p>

<p>&#8220;Unlike lithium‑ion batteries and many other sodium-ion batteries, Alsym’s Na-Series batteries are non‑combustible and thermally stable, reducing system complexity, improving safety, and lowering total cost of ownership by reducing the need for extensive fire suppression and HVAC infrastructure,&#8221; Selesky says. &#8220;Alsym’s Na-Series has been developed using a proprietary, physics-informed AI platform for battery development that dramatically shortens the time to bring innovation to the market.&#8221;</p>

<p>The sodium batteries also utilize non-FEOC sourced materials, Selesky adds, and those materials do not have the same inherent risk of <a href="https://solarbuildermag.com/news/check-for-battery-thermal-runaway-risk-in-the-dnv-battery-scorecard-yes-even-lfp-batteries/">thermal runaway</a> often present in traditional lithium-ion BESS products.</p>

<h3 class="wp-block-heading" id="h-supporting-growing-electrical-need">Supporting growing electrical need</h3>

<p>ESS Tech has put itself in a strong position, the company says, especially as electrical demand spikes around the U.S. and beyond. The sodium-ion batteries will be able to support not only straining utilities, but independent power producers and <a href="https://solarbuildermag.com/featured/data-center-download-how-hyperscalers-are-shaping-the-solar-storage-market/">data centers across the country</a>.</p>

<p>Calling ESS Tech a leader in stationary storage solutions, Alsym CEO Mukesh Chatter says he is excited to watch the partnership blossom between the firms. </p>

<p>&#8220;As demand grows, it is increasingly clear that the industry needs solutions beyond lithium-ion to meet the speed and scale projections,&#8221; Chatter says. &#8220;By combining high performance, inherent safety, and supply chain resilience, Alsym’s Na-Series delivers that capability and ESS brings deep experience delivering grid-scale systems that maximize the value of renewable energy. Together, we are enabling a better path forward for energy storage.&#8221;</p>

<p>In addition to strengthening the U.S. energy grid, the sodium-ion batteries will serve commercial and industrial customers, ESS says. The newly crafted BESS systems provide a flexible, and perhaps more importantly future-proofed, solution for a number of application in the commercial energy world.</p>
<p>-- Solar Builder magazine</p>