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EU-Rail May 2026 Newsletter
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Challenge
Conventional trains rely on pneumatic and hydraulic braking systems that are complex, maintenance-intensive, and limit system integration, while lacking the precision and responsiveness required for modern, digitally controlled rail operations. At the same time, rail systems waste significant amounts of energy because regenerative braking cannot always be absorbed by the grid and rely heavily on external electricity sources instead of locally generated renewable energy. Together, these limitations lead to reduced efficiency, higher energy costs, increased carbon emissions, and persistent challenges in ensuring safe and reliable braking under power or system failures
The solutions
To address this, Europe’s Rail (EU-Rail) Flagship Project FP4-Rail4Earth has developed:
Hybrid Energy Storage System for Train Braking and Photovoltaic Energy
An upgraded 3 kV DC traction substation integrating 1 MWp photovoltaic generation plus a hybrid storage architecture composed by a Supercapacitor-based Energy Storage System (ESS) and a Battery-based Battery Energy Storage System (BESS). The purpose is to capture regenerative braking energy and PV energy and feed it to the traction network.
Energy flows are managed via a voltage-based control strategy (charging on voltage rises, discharging on drops) using distinct voltage thresholds: supercapacitors act fast near nominal voltage, while batteries provide slower, higher-capacity balancing for Photovoltaic integration.
Simulation-based assessment using Trains Runner (time-domain traction simulations, compliant with EN 50388 and EN 50163) with real-world inputs (infrastructure, rolling stock categories, weekday/weekend timetables) to evaluate performance across seasonal Photovoltaic and traffic scenarios.
“Brake-by-wire” Airless-train Braking Demonstrator
As part of the broader “airless train” concept, this solution is developing and demonstrating an electro-mechanical Train Braking System (EMB) able to:
- Replace pneumatic/hydraulic dependencies with an electro-mechanical braking approach, supporting the “airless train” direction.
- Develop brake-by-wire control concept with a safety-oriented management approach (high-level), enabling precise braking modulation and system supervision.
- Integrate safe energy strategy concept (high-level) to maintain braking capability under degraded power conditions.
Readiness for Industrialisation and Deployment
Real pilot implementation of the Hybrid Energy Storage System for Train Braking and Photovoltaic Energy has been already planned, as the work will lead to a real upgrade of a railway substation (Fossalta Electrical Substation – Veneto, Italy). It is described as the first known pilot of its kind globally, serving as a “living laboratory” for validation and future replication.
The Current status of the solutions is a simulation-based baseline and design support. Next steps include real deployment and validation, and potential scaling to other substations.
Maturity level
TRL 5 (Technology validated in relevant environment) and 6 (Technology demonstrated in relevant environment)
Who benefits
Railway operators
Suppliers
Final users
Expected Benefits and Operational Impact
The solution is expected to reach the following benefits and impacts on the Hybrid Energy Storage System for Train Braking and Photovoltaic Energy:
- Energy savings (simulation-based) expect daily saving of about 2.9 MWh (weekday in summer – best case) and about 1.7 MWh (weekend in winter – worst case). That means that the expected yearly energy saving is about 1.1 GWh compared to the total energy drawn from the HV line, with a target of achieving up to 5% overall energy reduction;
- CO₂ savings: using the Italian energy mix (1 kWh = 360 gCO₂), annual CO₂ savings are estimated at around 382 tons;
- Operational benefit: supercapacitors help lower power peaks by quickly responding to traction demands, easing the load on the high-voltage grid.
Thanks to this, railway operators will be able to provide more efficient and sustainable operations, maintenance and reliability. Also, the final users will take advantage of better comfort and service quality, Finally, suppliers and integrators will benefit from a cleaner and more modular train-level design concept.
With regards to the “Brake-by-wire” Airless-train Braking Demonstrator, the following benefits and impacts are expected:
- Energy & system simplification: removing pneumatic subsystems can reduce energy consumption and simplify maintenance/operations.
- Operational performance: more precise braking force modulation can improve stopping accuracy and passenger comfort.
- Safety concept focus: safe energy availability strategy (high-level) supports robust braking under degraded conditions.
- Future-ready maintenance: supports advanced diagnostics / predictive maintenance direction (high-level).
Learn more about the project
FP4-Rail4Earth
This solution has been developed within the Europe’s Rail (EU-Rail) Flagship Project FP4-Rail4Earth. The project aims to is to improve the existing sustainability performance of railways, to build a more attractive and resilient transport mode and to contribute towards the objectives of a climate neutral Europe for 2050.