Storing Energy for the Future

The international “enera” project in Germany’s windy northwest is helping make wind power more reliable by supplying new electric batteries to stabilize the grid.

December 2020

One problem with wind-based electricity is always meeting demand – that puts a premium on storing power generated in windy periods to use in calmer times. This is precisely the goal of the “enera” project: a hybrid storage system in the northwestern German town of Varel.

The publicly funded initiative which partners German energy supplier EWE with Japanese companies – including Showa Denko Materials (formerly Hitachi Chemical), Hitachi Power Solutions and NGK Insulators – has now successfully completed its test phase, and its batteries are supplying electricity to the grid.

“Storage is vital to Germany’s transition to clean energy,” said Germany Trade & ­Invest energy expert Heiko Staubitz. “The enera project shows that Germany offers a lot of opportunities when it comes to integrating renewables into the energy market.”

The project combines two state-of-the-art battery technologies –“sprinters” and “marathon runners” – to stabilize the power supply. The sprinters are the ­lithium-ion batteries that can be rapidly charged and discharged, while the marathon runners are sodium-sulfur batteries, for long-term, larger capacity storage.

A hybrid renewable energy storage facility in Varel, northwestern Germany. The term ‘hybrid’ refers to the combination of two different technologies: Lithium-ion batteries are used along with ­sodium-sulfur ones to store wind power. © EWE AG

“I always compare these two technologies to a glass and a bottle of water,” says Magnus Pielke, head of be.storaged, the subsidiary set up to manage the project by EWE. “The glass is the lithium battery because it has a relatively small volume but a wide opening, so you can empty it quickly. The bottle has more volume, but the neck means you can’t get at the water as quickly.”

Saori Hamamura manages the NEDO consortium on the Japanese side. She says Japan is developing its own renewable energy system, similar to Germany’s. “We wanted to contribute to stabilizing the grid and developing a new business model with our battery system, but we didn’t have much experience in Japan because the market is different. Germany is the best country for renewable energy.”

Showa Denko made the ­lithium-ion batteries with a high power charge/discharge output, while NGK manufactured durable, large-capacity NAS® batteries. Hitachi developed the power grid data and battery control system.

Hamamura is very satisfied with the five-year cooperation with EWE. “We shared a lot of information and results with each other,” she says.

The two technologies are linked by computer banks that determine which batteries need to meet demand and which ones have to be charged. Data is crucial. So enera is planning to fit 30,000 smart meters into households and companies in the northwest. The state of Lower Saxony has become a pioneer of Germany’s transition to clean energy, using a higher proportion of renewables than most other German regions. “We expect battery storage to play a whole new role in the market,” says Pielke with satisfaction.

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