Pilot project in Hamburg: Hamburger Hochbahn AG and suena energy implement new operating model for urban battery storage
- Pia Armbruster
- Nov 4
- 4 min read
How can an energy project be both economically viable and climate-friendly – while also relieving the power grid of a major city? This question was at the heart of the pilot project by suena energy and Hamburger Hochbahn AG. Together, they operated a stationary battery storage system at the Alsterdorf bus depot in such a way that it optimized the depot’s own energy consumption while also actively participating in the electricity market — a model implemented for the first time in Germany in this form.
When Hamburger Hochbahn AG commissioned suena energy to market a stationary battery storage system at the Alsterdorf depot, the goal was to maximize revenues in the electricity and balancing power markets and to examine how battery storage could be used profitably at other sites. suena energy focused on an innovative approach: a combined multi-market strategy alternating semi-annually between front-of-the-meter (FtM) and behind-the-meter (BtM) operation, in full compliance with regulatory requirements. The system was controlled via the AI-based suena Energy Trading Autopilot.
Project Overview
Location: Bus depot Alsterdorf, Hamburg
Storage size: 4 MW / 4.6 MWh
Objective: positive contribution to grid stability and increased revenues
Operating model:
September – February:
BtM for atypical grid usage
March – August:
FtM market participation managed by suena energy
Hamburger Hochbahn AG – urban pioneers
Hamburger Hochbahn AG is Germany’s second-largest public transport company. With a modern network of subway and bus lines, it transports around 1.3 million passengers daily. Sustainability and innovation are central to its strategy — particularly through zero-emission buses, digital technologies, and the new fully automated U5 subway line, designed to be the most climate-friendly of its kind.
From battery storage to revenue source – our role
From March to August, suena energy assumed exclusive responsibility for the economic optimization and market participation of the stationary battery storage system.
Our roadmap to successful marketing included:
Full-service trading on day-ahead and intraday markets
Balancing group management and full market communication
Remote control of BESS based on forecasts and schedules
Performance monitoring and dashboard data provision
Compliance with all legal requirements (incl. REMIT, Redispatch 2.0)
"A particularly exciting aspect of the project was developing, togehter with Hamburger Energienetze, a solution that allowed the storage system to temporarily operate as an FtM system – despite its physical BtM connection." – Stefan Möws, Head of Operations, suena energy
Why urban energy storage solutions matter now
This project addresses key challenges of the energy transition in urban areas:
Dual use: grid relief and economic operation
High relevance for urban sites with limited space and grid capacity
Practical insights: technical integration, regulatory compliance, and combined usage scenarios
Complexity of dual operation
The economic operation of stationary battery storage systems involves numerous technical and regulatory challenges. Many projects lack standardized measurement and billing systems. The simultaneous use of a storage unit for grid stabilization and market participation raises complex regulatory issues.
In the case of Hamburger Hochbahn AG, the storage was to be used both for internal peak load management and for external trading. This dual-use concept required a complex, dynamically adjustable metering concept that clearly and cleanly separated both operating modes from an energy-economic perspective.
The key to dual use
The two operational phases were clearly defined in advance. suena energy held exclusive commercial responsibility during the marketing phase (March–August). In this period, system capacities were optimized economically on the day-ahead and intraday markets via the suena Energy Trading Autopilot.
A unique feature was the temporary FtM connection of the storage system. This was realized through close collaboration with Hamburger Energienetze, enabling market participation even though the system was technically configured as BtM.
During the non-marketing phase (September–February), operational control remained with Hamburger Hochbahn AG, which used the battery for internal peak load reduction. The result was a flexible, dual-use system, both regulatory-compliant and technically efficient.
Impact that sets new standards
For Hamburger Hochbahn AG, the project offered several strategic advantages. It provided valuable real-world experience operating a stationary battery storage system under changing usage conditions. Insights gained flowed directly into the planning of future depots, which could be designed with smaller grid connections without compromising operational security.
Furthermore, through its integration into the KoLa research project, the initiative contributed to the development of future-oriented technologies such as vehicle-to-grid and bidirectional grid connections.
For suena energy, the project validated the effectiveness of its multi-market strategy, even under technical constraints. The clear temporal separation of operating phases, combined with automated control and trading processes, enabled flexible participation in multiple energy markets. It also demonstrated that close coordination with grid operators and infrastructure partners can yield a regulatory-compliant, economically sustainable operating model.
Blueprint for the urban energy transition
Well designed BtM solutions with temporary FtM market participation and automated trading enable maximum value creation. Additional depots of Hamburger Hochbahn AG are already in planning. As part of the KoLa project, a coordination platform is being developed to identify and mitigate grid bottlenecks early on. Complementary AI-based energy and load management ensure operational load profiles align efficiently with both grid and market requirements.
The strategic collaboration between Hamburger Hochbahn AG, suena energy, and grid operators will continue to expand – setting new benchmarks for urban energy system innovation.
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