India’s metro rail systems are undergoing a structural shift towards integrated energy optimisation. Beyond merely expanding their geographic reach, they are rethinking how energy is consumed, generated and stored. This is driven by advances in regenerative technologies, battery storage, renewable integration, automation, digital engineering and emerging microgrid architectures. Across these domains, metro systems are shifting away from isolated measures towards an integrated and network-wide approach that reduces reliance on conventional grid supply, strengthens traction efficiency and improves long-term asset performance. Collectively, these developments indicate that the urban transportation sector is entering a more advanced phase, where technology, data and institutional preparedness align to create cleaner, more economical and resilient metro networks.
Converting braking systems into energy
Regenerative braking remains one of the most potent levers for energy savings in Indian metros. Many metros have adopted this braking system to ensure energy-efficient operations. Among these, Kolkata Metro has been successful in not only deploying this system in all its new rakes but also making significant energy savings. Its 37 rakes have been equipped with regenerative braking as of June 2025, and the trains have regenerated approximately 10.8 million units (MUs) of energy in 2024-25. This has helped the metro save about Rs 82 million in electricity costs and cut 13,500 tonnes of carbon emissions. According to studies conducted by Metro Railway Kolkata, about 17-20 per cent of traction energy can be recovered via such braking. This is a substantial fraction for a high-frequency urban rail network.
Moreover, integrating regenerative braking into metro trains not only enables energy optimisation but also reduces their mechanical wear over time. The advanced braking systems lower stress on wheels, brake discs and other components, thereby cutting down maintenance costs. Metro authorities have also tied this system to long-term sustainability. For instance, Kolkata Metro has also deployed a 4 MW advanced chemical cell battery energy storage system (BESS). This system is one of the first and one-of-its-kind in Indian Railways. This will allow better absorption and reuse of the regenerated energy.
Peak load management and BESS
BESS is emerging as a key enabler of smarter load management in metro networks. Metros can shift their energy consumption, shave peaks and smoothen their demand profile by deploying batteries at substations, depots or operation control centres (OCCs). This has two major benefits – reducing demand charges (especially under time-of-day tariffs) and capturing surplus renewable generation, such as solar. A major push in this direction came from the Delhi Metro Rail Corporation (DMRC), which floated a tender for 500 MUs of renewable power annually in October 2025. This is to be paired with BESS to power its operations. The project involves setting up a grid-connected captive generating plant with battery storage under a 25-year power purchase agreement (PPA). This also contributes to DMRC’s ambition to raise its share of renewables to over 60 per cent of its total energy consumption.
Combined with regenerative braking, BESS helps recapture braking energy that would otherwise go unused. This symbiosis between braking systems and storage can materially lower net imported energy, reduce peaks and contribute to a more stable and resilient traction network.
Renewable energy integration
Harnessing solar energy is critical for metro systems to abate their carbon footprint. Several recent initiatives illustrate how metros are creatively integrating PVs into their infrastructure. Adding to such efforts, the Ministry of Housing and Urban Affairs (MoHUA) inaugurated India’s first vertical bifacial solar panels mounted on the viaduct of Okhla Vihar metro station in Delhi. These panels, being bifacial, capture sunlight from both sides, maximising output from the elevated structure. Alongside this, DMRC has installed a 1 MW rooftop solar plant at its Khyber Pass depot, adding to its distributed solar generation capacity. Similarly, the metro system in Kanpur has already shown its concrete cost and environmental benefits. Its 1 MW rooftop solar plant on the OCC building of the metro station has saved Rs 20 million in two years. It also reduces emissions by around 770 tonnes per year, which is equivalent to planting nearly 9,000 trees.
Advanced and automated operations
Automatic train operations (ATO) and advanced signalling and communication systems, such as communications-based train control (CBTC), are increasingly being deployed in Indian metros not only to enhance safety and capacity, but also to improve energy efficiency. A prominent example is the recently launched Indore Metro, which has started revenue services with Alstom’s Movia trains equipped with a modern CBTC signalling system. These trains use energy-efficient traction systems and regenerative braking, while the signalling and control system supports optimised train movements and smoother acceleration, all contributing to lower total energy consumption. Similarly, the recently extended Kanpur Metro Corridor I features Alstom’s CBTC signalling, coupled with its energy-efficient propulsion system and regenerative braking, helping reduce operating energy demand under ATO.
Digitalisation enables energy cuts
Indian metro projects are increasingly leveraging upgraded technologies to embed energy efficiency into their lifecycle. The use of building information modelling, coupled with digital twin technologies, is being pushed by design firms for improving the planning of resources in project implementation, thereby optimising energy input. In line with this, recently, the Department of Telecommunications (DoT) and MoHUA have set up a joint working group to promote the use of digital twin models for urban transport networks such as metro corridors. This will help in drawing on telecom-derived mobility patterns to refine system design and day-to-day management. In parallel, DoT is collaborating with research institutions such as the Indian Institute of Science, IIT Kanpur and IIT Madras, along with agencies such as DMRC and Chennai Unified Metropolitan Transport Authority (CUMTA), to pilot and expand digital twin-based tools that support real-time asset diagnostics, passenger movement simulations and smarter operational planning across metro systems. In fact, CUMTA plans to create a telecom data-powered digital twin of Chennai’s mobility network. This will allow high-resolution tracking of travel patterns, generating ward-level origin-destination matrices and corridor-specific demand forecasts. The pilot, starting on a selected corridor, will help simulate metro ridership, test frequency changes and evaluate alignment or feeder-network options before roll-out. By integrating anonymised smartphone data, supplemented by CCTV and GPS inputs, the digital twin is positioned to sharply improve Chennai Metro’s capacity planning, peak-hour management and future network design.
More recently, metros are also embracing higher automation systems such as GoA-3 and GoA-4 with real-time controls to manage operations more efficiently. For example, in August 2025, Delhi Metro’s Magenta line achieved full driverless (GoA-4) operations, allowing more precise speed and braking control, which can indirectly support energy savings through optimised driving profiles. There is also potential for future integration of smart algorithms that optimise train speed, dwell times and braking to maximise energy regeneration and minimise losses. Though many of these remain in research or pilot stages, they represent a forward-looking frontier for metro energy systems.
Microgrids and local energy ecosystems
In parallel with braking systems, metros are increasingly experimenting with microgrid architectures to localise and manage power. Microgrids, combining solar PV, energy storage and smart controls, offer depots and major stations the flexibility to island during grid outages, manage their own load more intelligently and optimise on-site consumption. Metros in key cities such as Delhi, Bengaluru, Chennai and Mumbai are integrating energy-efficient infrastructure with these station-level micro-energy systems. However, scaling microgrids comes with associated challenges. High-capital costs, complex interconnection protocols with discoms and regulatory uncertainties around export and net-billing remain major obstacles. Some microgrid initiatives have been slowed by negotiations over protection, metering and contractual frameworks. Nevertheless, for depots and critical infrastructure such as OCC, microgrids remain one of the most promising ways to build resilience and lock in energy savings.
Institutional enablers and roadblocks
The success of energy optimisation in metros depends heavily on institutional frameworks, financing models and regulatory clarity. On the enabling side, metros are benefiting from policy alignment, such as national-level energy-storage guidelines, green-metro conference platforms and long-term PPA structures, making advanced energy investments more tractable. However, process fragmentation persists. Across states, discoms differ in how they allow energy export, net metering or grid interconnection for metro-owned generation and energy storage systems (ESSs). Such regulatory ambiguity slows down procurement and financing. Further, metro authorities often lack in-house capacity to evaluate and run energy service companies (ESCOs) or negotiate complex shared-savings contracts. To overcome these hurdles, metros need better capacity-building, stronger standards for ESS integration and model contracts to reduce negotiation risk with utilities.
Moving forward on track
The energy-optimisation journey of Indian metros is no longer aspirational; it is becoming operational. Through the synergistic deployment of various energy-saving measures, metros are increasingly building less carbon-intensive, cost-efficient and resilient systems. For the next phase, metros should focus on consolidating pilots (such as solar-on-track), scaling microgrid projects at depots, integrating ESS deeply with braking systems and standardising commercial and regulatory frameworks with utilities.
Realistically, Indian metros can aim to reduce their net grid electricity purchases in the near term if these strategies are adopted coherently. Achieving this will require not just technological roll-out but institutional maturity, and alignment of metros, regulators, ESCOs and discoms around shared energy-management goals. Once accomplished, this transformation will not only reduce costs and emissions but also set a global benchmark for how dense and high-frequency urban rail networks can become self-reliant and energy-optimised systems.
Shubhangi Goswami
