Iron flow battery firm ESS Inc to build 50MW/500MWh system for LEAG in Germany

LinkedIn
Twitter
Reddit
Facebook
Email

Iron-saltwater flow battery company ESS Inc looks set to deploy by far its largest project to-date, a 50MW/500MWh system at a renewables hub from German energy firm LEAG, with potential for more.

The NYSE-listed firm is partnering with LEAG on a new renewables hub located at the site of the Boxberg Power Plant, a 2.5GW lignite-burning facility.

A ten-hour duration system using ESS Inc’s (full name ESS Tech Inc) iron and saltwater electrolyte long-duration energy storage (LDES) technology will be commissioned at the site in 2027. The firm offers durations generally of 6-12 hours.

The system is expected to become a standardised building block in LEAG’s plan to deploy 2-3GWh of energy storage as part of the transformation of its legacy power plants. The process will also involve the deployment of 7-14GW of renewable energy generation and 2GW of green hydrogen production, although the announcement did not say how much was planned for the Boxberg site specifically.

This article requires Premium SubscriptionBasic (FREE) Subscription

Try Premium for just $1

  • Full premium access for the first month at only $1
  • Converts to an annual rate after 30 days unless cancelled
  • Cancel anytime during the trial period

Premium Benefits

  • Expert industry analysis and interviews
  • Digital access to PV Tech Power journal
  • Exclusive event discounts

Or get the full Premium subscription right away

Or continue reading this article for free

The project still requires definitive agreements and normal financial close which are anticipated to conclude in the third quarter of this year. LEAG and partners plan to invest €200 million with further support anticipated from additional investors and stakeholders, the announcement, made at Ees Europe today, added.

LEAG and ESS Inc have also joined the Energy Resilience Leadership Group (ERLG), an initiative led by Bill Gates-founded Breakthrough Energy and Siemens Energy, founded at the 2023 Munich Security Conference to enhance Europe’s energy resilience by bringing clean energy tech to scale. LEAG and ESS Inc’s project is one of those that the ERLG is working to accelerate.

“A key requirement for our transformation into Germany’s Green Powerhouse is the deployment of cost-effective Long-Duration Energy Storage. We are energised to demonstrate the value of iron flow battery technology at scale,” said Thorsten Kramer, CEO of LEAG.

“The Energy Resilience Leadership Group and Breakthrough Energy have provided an ideal framework to drive rapid technology development and deployment to meet emissions goals as soon as possible.”

Eric Dresselhuys, CEO of ESS, added: “The deployment of renewables and long-duration energy storage will not only deliver reliable, clean energy to effectively replace the baseload power currently provided by coal, it will deliver economic opportunity and a cleaner environment for Germany.”

If it goes ahead it will be by far the company’s largest deployment to-date. It is fairly early on in its path to large-scale commercialisation, with just under US$1 million in revenue last year and recent projects in the kWh range. It finished 2022 with a production capacity of 800MWh.

LEAG until recently had the largest battery energy storage system (BESS) operational in Germany, the 66MW Big Battery Lausitz.

3 November 2026
Málaga, Spain
Understanding technology and supplier selection for Europe’s utility-scale PV market in 2027. PV ModuleTech Europe 2026 is a two-day conference that tackles these challenges directly, with an agenda that addresses all aspects of PV module, inverter and battery supplier selection; product availability, technology offerings, supply chain traceability, quality assurance, factory auditing, system reliability, and supplier bankability.

Read Next

Premium
September 24, 2026
We recently caught up with Georg Gallmetzer, managing director of German BESS platform Eco Stor, about the firm’s role in formulating flexible connection agreements (FCAs) and how this was intimately tied to the debate on grid fees. 
Premium
September 23, 2026
Compressed air energy storage (CAES) holds much promise for large-scale, LDES, but has struggled to get off the ground outside of China.
September 22, 2026
Utility PG&E has selected six new California microgrid projects for a US$30 million investment, while Massachusetts’ Department of Energy Resources is awarding US$40 million across 36 BESS projects.
September 21, 2026
The US energy storage industry is targeting 225GW/1TWh of storage deployment by the end of 2032, according to an analysis published by the Energy Storage Coalition (ESC).
September 21, 2026
Poland’s grid-scale storage market has reached an impressive scale in the last few years, helped by the capacity market and various government schemes, but numerous challenges now need to be overcome.