CellCube stands as a pioneering force in sustainable, long-lifecycle energy storage—offering modular, safe, bankable, and environmentally conscious battery systems built to power the clean energy transition.
Interview with Christoph Stelzer, COO of CellCube Energy Storage GmbH.
A brief description of the company and its activities
Christoph Stelzer: CellCube Energy Storage GmbH (formerly Enerox GmbH) is a leader in vanadium redox flow battery (VRFB) technology. Designed and manufactured in Austria, we develop, produce, and deploy long-duration energy storage systems that deliver 4 to over 24 hours of reliable power, with at least 20,000 cycles over a 30-year lifetime, and no degradation of capacity.
What are the main areas of activity of the company?
C.S: Our core activities include:
- Engineering and manufacturing robust, modular VRFB systems.
- Deploying solutions across grids, microgrids, renewables integration, and critical infrastructure.
- Ensuring turnkey delivery—from stack design to remote management and maintenance.
What’s the news about new products/services?
C.S: Our latest major milestone is the release of CellCube Release 4.2, which delivers +33% more power and +33% more energy capacity — all within the same housing and footprint as previous models. This upgrade significantly boosts customer ROI by allowing more storage and output without increasing space requirements or installation complexity. In parallel, we have expanded into North America the last years via our subsidiary, CellCube Inc., based in Denver, Colorado—strengthening local supply chains and deepening regional partnerships.
What are the ranges of products/services?
C.S: We offer modular VRFB systems fully scalable from kilowatt to multi‑megawatt power outputs, with rated storage durations ranging from 4 to 10 hours, and customizable up to 24 hours.
What is the state of the market where you are currently active?
C.S: The global market for long-duration energy storage is experiencing explosive demand, driven by the growing need for reliable grid balancing and renewables integration. Europe, where we’re headquartered, remains a strategic hub, and our entrance into North America marks an important expansion.
What can you tell us about market trends?
C.S: Key trends include:
- Increasing demand for storage durations exceeding 4 hours.
- Heightened focus on circular economy, safety, and lifecycle sustainability.
- Movement toward performance-backed, bankable systems—highlighted by our 20-year performance warranty insured by Munich Re.
A growing market emphasis on proven technology, where CellCube stands apart. We have more than 140 deployments worldwide, have been operating since 2000, and proudly delivered the oldest flow battery still in operation globally — installed at an Austrian utility in 2010 and running reliably to this day.
What are the most innovative products/services marketed?
C.S: Our standout innovations:
- Non‑flammable VRFBs with double-wall leak detection, UL9540A certification, and strong safety profile.
- Systems engineered for 100% Depth of Discharge, millisecond response, and exceptional thermal resilience.
- Sustainable design with reusable vanadium electrolyte, promoting a circular economy.
What estimations do you have for the second half of 2025?
C.S: As COO, I’m projecting:
- Continued deployment of large-scale VRFB solutions in Europe and North America.
- Strategic collaborations and installations in microgrids and utility markets.
- Greater adoption of our bankable business model, combining long-term service products with performance-backed guarantees to support financing and scale.