Japanese sodium-sulfur and lithium batteries used in German grid demonstrator project

LinkedIn
Twitter
Reddit
Facebook
Email
The hybrid energy storage system in Niedersachsen, Germany. Image: Hitachi.

A ceremony was held yesterday in Niedersachsen, Germany, to welcome the start of operations at a ‘hybrid’ energy storage plant that will use a combination of sodium-sulfur and lithium-ion batteries to stabilise the grid.

The project uses 4MW / 20MWh of sodium-sulfur NAS battery storage from NGK Insulators with 7.5MW / 2.5MWh of lithium-ion batteries, each performing different grid-balancing roles. NGK, Hitachi Chemical and Hitachi Power Solutions, supplier of battery control and power grid information technologies, were appointed by NEDO (New Energy and Industrial Technology Development Organisation) of the Japanese government.

Through Niedersachsen’s Ministry for Economics, Labour and Transport and authorities in the City of Varel where the demonstration project is located, NEDO teamed up with EWE-Verband, the region’s energy provider. It got underway after city authorities signed off permission to “establish a large-scale power storage system” in April 2017 to run for a three-year demonstration period to February 2020.

As Germany targets 80% of its domestic power supply to come from renewable sources by 2050 with conventional power plants being replaced by wind and solar, the stabilising role that thermal power generators can play is now being addressed by combining the NGK batteries – storing energy for long durations and output at 4MW for five hours without incurring higher costs or shortened battery lifetime through degradation – and lithium-ion, which are high power with rapid charge and discharge.

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

Varel and the wider Niedersachsen region is experiencing an increase in wind power on the grid, which the energy storage system will help balance through four primary functions, while also being used to try and establish business models for energy trading. The system will provide primary and secondary reserve power to the grid, which are two steps of frequency regulation or frequency control that maintain stability through balancing supply and demand.

Primary reserve is activated within 30 seconds of receiving a grid signal from power distributors, secondary control reserve within five minutes. It will also provide balancing within the local grid network, ensuring actual supply and demand to the grid matches forecasted and planned supply and demand. Finally the system will manage reactive power supply to stabilise local voltage.

From there, it is hoped it can be used to aggregate several distributed energy resources into virtual power plant (VPP) networks, while continuing to support the aims of ‘enera project’, EWE’s energy transition programme which seeks innovative business models that can drive reductions in network expansion costs while managing the decline in fossil fuel use.

The ceremony yesterday was attended by Japan’s ambassador to Germany, Takeshi Yagi, and Germany’s Parliamentary State Secretary to the Federal Minister for Transport and Digital Infrastructure, Enak Ferleman.

Read Energy-Storage.news’ 2017 sponsored interview with NGK Italy’s Naoki Hirai, discussing the NAS sodium sulfur grid-scale batteries in depth.

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

September 18, 2026
A roundup of some of our key takeaways from the Energy Storage Summit Germany this week, including around FCAs, inertia, the capacity market (CM), EU restrictions on China, and the future of one very notable system integrator.
September 16, 2026
LFP is the de facto choice for the German BESS market today with sodium-ion still far from bankable, but that doesn’t mean choosing a supplier is necessarily straightforward. 
September 16, 2026
Zelestra and steelmaker Salzgitter Flachstahl have signed a PPA for a new solar-plus-storage portfolio in Germany.
September 16, 2026
OCP Green Energy has completed the installation of a 25MW/125MWh battery energy storage system (BESS) in Benguerir, Morocco.
September 15, 2026
Flexible Connection Agreements (FCAs) must not be used simply to exclude BESS from connecting to the grid, but the industry will have to make do with them and all their imperfections for the foreseeable.