The global transportation network emits significant levels of greenhouse gases, consumes substantial amounts of fossil fuels and creates a major environmental footprint. In 2021, for instance, the European transportation sector accounted for 24 percent of the European Union’s (EU’s) total greenhouse gas (GHG) emissions »01.

Rail innovation

All transport sectors – cars, buses, trains, airplanes and ships – are working to reduce their GHG emissions. Rail transport, for instance, while already a low emitter, has witnessed significant advancements in efficiency and sustainability, with initiatives aimed at digitalization, low-emission technology and infrastructure optimization. ABB has been leading that innovation.

There are numerous examples of innovation in the rail sector. For instance, the European Rail Traffic Management System is a unified signaling platform that ensures trains are scheduled more efficiently, reducing energy consumption.

Another significant innovation is the development of energy-efficient rail vehicles. Projects such as FP4 Rail4EARTH, supported by the EU and Europe’s Rail (an EU body), are advancing the use of lightweight materials, 3-D-printed parts and alternative propulsion systems. In 2025, this initiative is due to demonstrate hydrogen and battery-electric trains as part of its extensive testing across multiple sectors.

Additionally, new eco-friendly heating, ventilation and air conditioning (HVAC) systems, noise reduction technologies and modular train designs are being implemented, all to reduce life cycle costs and enhance environmental sustainability [2]

A full suite of products for electrification

The ongoing electrification of railways is significantly reducing energy consumption and increasing the use of green energy sources, ultimately lowering the carbon footprint of rail transportation. By 2022, approximately 57 percent of the entire EU rail network was electrified [3] and ABB is at the forefront of this transition with an extensive product portfolio. ABB has facilitated a major shift in rail electrification as well as improvements in efficiency on board rolling stock. This is provided through a comprehensive suite of products, such as traction-power converters and lithium-ion-based energy-storage systems. In this context, the ABB Traction Battery Pro series, the latest addition to ABB’s already extensive Traction Battery family, is designed to provide modularity and scalability, as well as top-tier performance, a high level of safety and superior energy density in a compact design »02.

ABB drivetrains are designed to manage the stop-and-go nature of public transit, ensuring a smooth experience for passengers while reducing energy consumption. ABB’s offerings support both new vehicles and fleet refurbishments, helping cities modernize their public transit systems with minimal disruption.

When it comes to motion, ABB traction converters transform the stored direct current (DC) electricity from batteries into the alternating current (AC) electricity needed to power the motors that move the vehicle. These converters are designed to optimize energy efficiency and lower operating costs, making them an excellent choice for urban transit authorities aiming to enhance sustainability.

Regenerative braking

When a train decelerates, regenerative braking converts kinetic energy back into electrical energy that can be fed into the power grid, stored on the train for reuse, or used to power other trains on the same network. Regenerative braking can reduce overall energy consumption by as much as 30 percent for rail systems [4], which directly translates to lower carbon emissions, reduced reliance on fossil fuels and lower operational costs. Notably, this technology is already widely used in electric and hybrid trains in Europe (See also: “Buzzword Demystifier: Regenerative Braking” on this edition of ABB Review).

The ABB Enviline Energy Recuperation System (ERS) [5] »03, for example, is at the forefront of regenerative braking harnessing technologies. This ERS returns surplus braking energy from rail DC networks to the AC network and can be installed in a modular way, outside of current substations, to minimize costs and disruption during installation.

Alternatively, the ABB Enviline Traction Controlled Rectifier (TCR) [6] can be used as a bidirectional converter, offering advantages over rectifier-inverter setups by reducing the number of assets required for purchase and maintenance and allowing for easy replacement of outdated rectifier sets. Additionally, the Enviline Energy Storage System (ESS) [7] captures energy when it is not needed for other purposes and makes it available for later use, aiding a transition toward a more environmentally friendly rail sector »04. Furthermore, the regenerative braking ecosystem supports other sustainability initiatives, such as the integration of renewable energy sources.

Integration of transport modes

In most rail networks, the use of regenerative braking is not optimized. The current approach depends on another train being on the same track section as the one braking so that regenerative energy can be utilized. This is not always the case, leading to energy wastage. To help reduce this waste, battery storage or new users, such as electric vehicle (EV) chargers, could be incorporated. Allowing EV charging infrastructure to take advantage of rail regenerative braking (as well as off-peak and redundant spare-energy capacity in the transport power network) would also help alleviate some barriers to EV adoption, such as insufficient charging infrastructure or limitations of the national grid.

A homogeneous integrated rail and road power network

When introducing an innovative cooling panel to the London Underground transport system as part of the TIES Living Lab Program (a multi-partner collaborative), ABB partner Green Energy Futures (GEF) investigated all heat sources within the tube network »05. Regenerative braking was identified as one such source. GEF has been collaborating with rail network providers and ABB to deliver the optimal solution to this thermal challenge. That solution is, ultimately, a homogeneous integrated rail and road power network.

Accordingly, GEF and ABB are working together in London to develop business cases to trial ABB’s regenerative braking capture and storage technology within rail infrastructure for EV charging (for buses, freight, vans, cars, etc.). Engagement is ongoing with rail infrastructure companies, such as Transport for London (TfL) and Network Rail (NR), as well as discussions with the UK Department for Transport (DfT). ABB and GEF are continuing to enhance the ABB product family to meet the requirements of transport (road and rail) infrastructure in the sustainable transportation field.

To date, regenerative braking technology has not been widely adopted, primarily because it requires significant capital investments that are recovered over several years through energy savings. By utilizing captured braking energy in EVs, the business case shifts entirely, as a substantial additional revenue stream is generated through the sale of electricity.

05 Green Energy Futures (GEF)

GEF is a multi-partner initiative that specializes in delivering innovative solutions for a low-carbon future. Across three core divisions: advisory and consultancy; installation and fit-out; and research and development; GEF helps organizations to reduce emissions, enhance energy performance and build climate-resilient infrastructure. GEF partners with public and private sector clients to transform sustainability targets into practical outcomes by mapping clear decarbonization pathways and executing turnkey projects from concept to commissioning.

The advisory and consultancy team collaborates closely with clients to assess existing energy systems, benchmark performance against industry best practices and identify high-impact opportunities for improving efficiency and integrating renewables. The Installation and fit-out division procures, constructs and commissions tailored solutions − ranging from solar panels to EV charging points. Behind the scenes, GEF’s research and development arm addresses real-world challenges by developing scalable innovations rooted in regulatory insight and sustainable design principles

One of GEF’s flagship innovative technologies is its homogenized rail and road power network concept, coined RailGrid. Developed in collaboration with leading rail operators, RailGrid captures surplus traction energy generated during braking and channels it into powering EVs. This closed-loop approach prevents energy wastage and reduces peak loading on local substations, eliminating the need for costly grid reinforcement. Its modular design allows seamless integration of rail and road, enabling rapid deployment with minimal civil works.

By directing the captured energy into EV charging stations, RailGrid accelerates the roll-out of EV infrastructure in areas where grid capacity is constrained. By linking rail and road energy networks, RailGrid cuts carbon emissions and unlocks new revenue streams for rail operators. The approach also creates a more connected, resilient transport ecosystem that supports faster, cleaner mobility solutions at scale.

Future of transport networks

Overall, rail’s low-emission profile, reduced reliance on fossil fuels and energy efficiency make it an essential component of Europe’s sustainability strategy for transportation.

ABB’s innovations lead the way in reducing emissions in the rail sector and support electrification with converters, motors and battery products. ABB continues to drive innovation in regenerative braking and, through its strategic partnership with GEF, its technology will help further reduce railway emissions. Additionally, ABB’s technology offers new use cases for rail power infrastructure, aiming to become the backbone of future sustainable transportation networks. ABB and GEF are collaborating to extend ABB’s technology beyond the rail network and develop a unified transportation system for both road and rail.

References

IEA, “Rapid expansion of batteries will be crucial to meet climate and energy security goals set at COP28”, IEA News 25 April 2024, Available: https://www.iea.org/news/rapid-expansion-of-batteries-will-be-crucial-to-meet-climate-and-energy-security-goals-set-at-cop28

G. Jarbratt, et al., “Enabling renewable energy with battery energy storage systems”, McKinsey, 2 Aug. 2023, Available: https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/enabling-renewable-energy-with-battery-energy-storage-systems

N. Nsitem, “Global Energy Storage Market Records Biggest Jump Yet”, in Bloomberg NEF, 25 April 2024, [Online].

G.P. Guddanti et al., “A Comprehensive Review: Impacts of Extreme Temperatures due to Climate Change on Power Grid Infrastructure and Operation”, in Electrical Engineering and System Science; Systems and Control, Dec. 2024, Available: https://arxiv.org/abs/2410.08425