Athens Metro tests regenerative braking on Line 1

The Athens Metro has begun testing a regenerative braking system on its historic Line 1, a pilot project that aims to recover energy during train braking and feed it back into the network, potentially reducing both electricity consumption and emissions across the Greek capital’s urban rail system.

Pilot project launches on the Piraeus–Kifissia corridor

According to recent coverage in Greek media, the pilot is being carried out by Urban Rail Transport operator STASY on Line 1, which links the port of Piraeus with the northern suburb of Kifissia. The test phase focuses on upgraded traction substations where the new technology is being integrated into existing power infrastructure.

Publicly available information indicates that the system captures kinetic energy generated when trains slow down, converts it into electricity and returns it to the metro’s power supply. When there is sufficient demand from nearby trains, this recovered energy can be reused almost immediately, reducing the need for fresh power from the grid.

Line 1 is one of the busiest axes in the Athens network and runs largely above ground, making it a high-visibility testbed for new technology. If the trials confirm projected savings and reliability, the system is expected to be considered for wider deployment on the newer underground Lines 2 and 3.

Energy savings and emissions cuts at the heart of the scheme

Project documentation from STASY describes the initiative as a flagship “green” investment for the Athens network. Company material on the renovation of two Line 1 traction substations in Neo Faliro and Iraklio notes that installing energy recovery equipment could reclaim thousands of megawatt hours of electricity annually, equivalent to a significant share of the line’s yearly consumption.

Earlier sustainability reports from the Athens transport group have already pointed to braking energy recovery on Line 1 as a pathway to double-digit percentage reductions in traction power use. The current tests are seen as a move from planning and procurement into full operational validation, with the aim of locking in those efficiency gains under real-world conditions.

Beyond lower electricity bills for the operator, reduced energy demand is expected to cut the carbon footprint of the metro, given that a portion of Greece’s power supply is still generated from fossil fuels. Regenerative braking is widely regarded in the rail sector as one of the most direct ways to improve environmental performance without altering timetables or service frequencies.

Technology partners and EU-backed financing

Information published by STASY shows that the energy recovery project on Line 1 is being delivered in cooperation with Siemens Mobility, which is providing and integrating the traction substation upgrades. The contract, signed in 2024, covers both the renovation of aging substations and the installation of the new recovery hardware and control systems.

The scheme is financed through Greece’s European Union co-funded development programs, with the budget for the Line 1 substations reported at just over 4 million euros. Using EU structural funds allows the operator to combine technical modernization with environmental objectives under the wider framework of the European Green Deal.

Local reporting notes that Siemens Mobility is responsible for supplying equipment capable of converting the direct current from train braking into usable energy for the metro’s electrical network. The company has previously deployed similar solutions on other European urban rail systems, a factor that appears to have weighed in during the tender process for the Athens contract.

From Line 1 pilot to wider network roll-out

Public statements from the operator outline a staged approach: first deploy the system on Line 1, measure its performance and then evaluate extensions to Lines 2 and 3 and to future infrastructure such as Line 4. The current tests are therefore being closely watched as a benchmark for subsequent investment decisions across the network.

Technical material from Elliniko Metro, the state-owned project delivery company, highlights parallel research into hybrid energy storage solutions that use recovered braking energy to power station equipment such as lighting and escalators. The Line 1 tests are expected to provide real operating data that can inform these research efforts and help refine design assumptions.

For passengers, the changes are largely invisible, as regenerative braking works behind the scenes without altering ride comfort or journey times. For engineers and planners, however, the pilot is a key opportunity to understand how the technology performs in Athens’ specific operating environment, including its mix of older and newer rolling stock and varied gradients along the line.

Athens aligns with global rail efficiency trends

Regenerative braking has been adopted on metro and suburban rail systems worldwide, from Delhi to London, as operators seek to capture energy that would otherwise be lost as heat in traditional braking systems. Recent academic studies underline that pairing regenerative braking with optimized timetables can substantially cut net energy use across entire metro networks.

The Athens initiative positions the city within this broader shift toward more energy-efficient urban rail. Reports on the Line 1 project note that once the system is fully commissioned, the operator will monitor not only headline energy savings but also impacts on network stability, equipment wear and long-term maintenance costs.

As Athens continues to expand and modernize its metro infrastructure, including the construction of the new Line 4 and upgrades to existing lines, the experience gained from the current tests is expected to shape how future power systems are specified. For a network that carries hundreds of thousands of passengers daily, even incremental improvements in energy performance could translate into meaningful environmental and financial benefits over time.