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European energy majors Equinor, Uniper get involved in flow battery investment and pilot project


Equinor has led an investment round for a flow battery manufacturer, while Uniper has just announced it will carry out a megawatt-scale flow battery energy storage pilot project.

Perhaps the latest indication that market interest in flow batteries is getting serious, both companies are major players in Europe’s energy sector, albeit their first steps into the space are relatively small ones.

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The corporate venture capital (VC) arm of Norwegian state-owned energy company Equinor – formerly known as Statoil – led a consortium a €30 million Series A funding round for Dutch flow battery company Elestor.

The round successfully closed and was co-led by Dutch impact investment group Invest NL, which was launched by the Netherlands government in 2020 as a private company investing public funds in sustainable and innovative companies from the country. Invest NL said it invested 15 million (US$29.95 million) through the funding round, backed with a European Investment Fund (EIF) guarantee.

Elestor has developed a flow battery with hydrogen and bromine as active materials. Designed for long-duration energy storage (LDES) applications, the system also generates hydrogen during the charging process, which means it could be paired with electrolysers and hydrogen infrastructure.

The company intends to use the investment towards gearing up for mass production from a gigafactory. It has been deploying pilot projects since 2016, a year after its founding. Last year the company entered a partnership with tank storage company Royal Vopak to develop technologies to scale up Elestor’s systems from large commercial (200kWh) size to utility-scale (3,000kWh).   

Royal Vopak was among other investors in the consortium, along with investment firm Somerset Capital Partners, European innovation accelerator EIT InnoEnergy and Dutch sustainability VC Enfuro Ventures.

“Technologies providing long-term energy storage at scale will play an important role in satisfying the growing need to stabilise power markets,” Equinor Ventures chief Gareth Burns said.

“Elestor’s hydrogen bromide flow battery holds tremendous potential for scaling up quickly and thus to speed up the Dutch transition towards a carbon-neutral and circular economy,” Invest NL’s capital director Leo Holwerda said.  

While vanadium is the most popular and well-known choice of electrolyte active material for redox flow batteries, Elestor is among a handful of companies trying different materials. Other alternatives include zinc bromine and iron and saltwater along with some newer alternatives from the likes of Honeywell and Lockheed Martin for which electroyte composition has not been disclosed ahead of their first deployments in the field.

Elestor claims it chose hydrogen and bromine due to their abundance and low cost which could enable scaling to production at high volumes, while the materials also offer relatively high energy and power density.  

In a recent guest blog for this site, energy storage industry expert and organiser of the International Flow Battery Forum Anthony Price argued that Europe will not be able to meet its decarbonisation goals without leveraging the capabilities of flow batteries to decouple power and energy, thus enabling long-duration storage at large scales.

Uniper to pilot ‘Organic Solid-Flow Battery’ tech

In Germany, another company called CMBlu Energy has developed a flow battery using an organic carbon-based electrolyte, which it claims can achieve up to 90% round trip efficiency, only about 5% less than lithium-ion batteries. The company claims its devices, which it calls Organic Solid-Flow Batteries, can be even longer life than other redox flow batteries that use metal ions.

Uniper, the power generation group spun out of European utility company E.On, is partnering with CMBlu to install one of its systems at the site of Uniper’s Staudinger power plant in Großkrotzenburg, near Frankfurt, Germany.

An Organic Solid-Flow Battery system with an initial 1MW/1MWh output and capacity will be installed to evaluate its performance across a range of applications. Based on the outcome, the system could be expanded, and the technology could be integrated into the power plant’s operations. That would also hand the technology certification for use at a power plant facility, Uniper said, and the flow batteries could be deployed at other locations by the power gen group.

The pilot is expected to be commissioned in early 2023.

“In terms of sustainable climate protection, we need high-performance stationary electricity storage for renewable energy volumes. The increasing electrification of processes in industry and in private households is leading to a growing need for base-load capability from renewable energies to maintain security of supply,” Uniper director of innovation Arne Hauner said.

“Solid-flow batteries are ideally suited for this purpose in Uniper’s view.” 

In June, CMBlu started a similar pilot programme with an Austrian utility, Burgenland Energie, as reported by at the time.  

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