La Municipal Transport Company of Madrid has taken another step in its commitment to electric mobility with a project that transforms batteries removed from its buses into a useful resource for the depot's energy system. Instead of discarding these components when they lose some of their capacity, the company is repurposing as stationary storage at its Fuencarral Operations Center.
This initiative, developed in collaboration with Iberdrola and Irizar e-mobilityThis positions the capital as one of the leading European centers in circular economy applied to public transportThe goal is clear: to extend the lifespan of batteries, reduce waste, optimize the charging of the electric fleet, and contain the energy bill by taking advantage of off-peak electricity hours.
A pioneering project to extend the lifespan of batteries
At the operations center of Fuencarral a has been installed static energy storage container which integrates batteries from EMT Madrid electric buses. These batteries have lost some of their traction capacity after years of intensive use, but remain fully valid as stationary storage systems to support the refueling of the fleet.
According to the municipal company, the system groups batteries in their second life cycle, withdrawals of three electric vehicles that no longer achieved the performance required to operate online, typically when they drop below around 80% of its original capacityAlthough they are no longer optimal for moving the bus, they retain enough capacity to play a key role in the energy support of the garages.
The delegate for Urban Planning, Environment and Mobility, Borja Carabante, who visited the facilities along with the managing director of EMT, Alfonso Sanchez, has emphasized that the project is integrated into the fleet electrification strategy and in the city's commitment to innovation and public-private partnerships. In his words, the aim is "to give a second life to batteries that can no longer be used in buses" and to transform what was once waste into an energy asset.
From a technical point of view, the container acts as a large stationary accumulator It recharges during periods when electricity is cheaper, mainly at night, and discharges during the day to support the recharging of buses. In this way, the installation allows shift part of consumption outside of peak hours and alleviate the power demand on the grid during periods of highest activity. This approach aligns with current trends energy storage and flexibility in garages.
This initial deployment has been designed as a pilot projectHowever, the city's plan is for the model to be gradually extended to other operating centers, taking advantage of the growing availability of batteries removed from the fleet and the constant increase in the number of electric buses in service.
1 MWh capacity and integration with smart charging
The Fuencarral container has a maximum storage capacity of 1 MWh and a power of 500 kW charging and unloadingThis allows it to act as a kind of "energy lung" for the garage. Inside, it houses three battery racks sourced from electric buses in the EMT Madrid fleet, already adapted for stationary use.
These batteries are charged in optimized pricing periodsprimarily taking advantage of nighttime hours, when energy costs are lower. Later, during the day, the stored energy is used for support the recharging of other vehiclesreducing the power demanded from the grid during peak hours and smoothing out consumption peaks.
The system is integrated into the platform of smartcharging by EMT Madridwhich manages the daily charging of Fuencarral's electric buses. Thanks to this integration, the container can be coordinated with the charging points for optimize available power, reducing peaks and adjusting the process to the different tariff periods, resulting in a more efficient use of the garage's electrical infrastructure.
The solution is initially operational for recharging about twenty electric busesHowever, the municipal company plans to scale up its operations as more second-life batteries are incorporated. This approach opens the door to the creation of genuine “battery farms” serving Madrid's public transport, capable of providing flexibility to the local electrical system.
In addition to reducing energy bills, the combination of stationary storage and smart charging contributes to strengthen network stability in the vicinity of garages, as it mitigates the peak demand associated with the simultaneous charging of dozens of electric vehicles.
Sustainability and circular economy in public transport
Beyond its technical dimension, the project has a marked aspect of environmental sustainability and circular economyReusing batteries once their first useful life in buses is over allows avoid its immediate conversion into waste and postpone the moment when they must be recycled, thus reducing the pressure on waste management systems and on the manufacture of new components.
By giving them a second life, they decreases the consumption of raw materials necessary to produce new batteries and mitigate some of the environmental and social impacts associated with mineral extraction and industrial processes. This approach fits with the European roadmap towards a cleaner mobility model and with the principles of the circular economy promoted by the European Union.
The initiative also contributes to consolidating a More efficient and responsible public transport In Madrid. By combining electrified fleets, smart charging and component reuse, EMT is moving towards a mobility system that not only reduces emissions during vehicle operation, but also pays attention to the complete life cycle of its main elements.
The municipal company emphasizes that, with these types of solutions, what was previously destined to become waste becomes a tool for power the charging network itself of the buses. This logic of reuse allows us to address one of the great challenges of urban electric mobility: deciding what to do with the batteries when they are no longer suitable for traction after seven or eight years of intensive service and how to document their traceability through a battery passport.
The Fuencarral project is also conceived as an experience that can serve as reference for other European cities with electrified bus networks, showing how to integrate the second life of batteries into the routine management of bus depots and urban energy planning.
Collaboration with Iberdrola and Irizar e-mobility
The development of the second-life battery storage system is the result of the collaboration between EMT Madrid, Iberdrola and Irizar e-mobilityEach of these actors has assumed a specific role within the project to guarantee both the technical viability and the economic efficiency of the solution.
Iberdrola participates as energy partner, within the framework of the PERTE VEC programcontributing their experience in energy management and the integration of storage systems with the electrical grid. Their key responsibilities include: definition of technical specifications of the system and the validation of the prototype from the point of view of efficiency and cost reduction.
For its part, Irizar e-mobilityThe manufacturer of EMT's electric buses has been responsible for design and develop the energy storage containerThe company has adapted traction battery technology for use in stationary applications, ensuring its safe and reliable integration into the garage infrastructure.
This public-private partnership reinforces Madrid's role as a testing ground for innovative solutions in electric mobilityThis project also strengthens collaboration between transport operators, energy suppliers, and vehicle manufacturers. It is envisioned as a foundation upon which to scale new distributed storage applications to other operational centers.
The idea of expand this model The electrification of the rest of the city's garages is already on the table, with special attention to future centers like La Elipa, designed to operate a fully electric fleet and where second-life batteries and integration with photovoltaic energy can play a relevant role.
Increasing electrification of the EMT Madrid fleet
The battery reuse project is part of the continuous process of fleet electrification of the Municipal Transport Company, one of the cornerstones of Madrid's public transport decarbonization strategy. Currently, EMT has 452 electric buses and around 410 charging points, distributed among the operations centers of Carabanchel, Fuencarral, Entrevías and SanchinarroThese advances are part of initiatives such as the European Mobility Week, which promote the dissemination of good practices.
As the municipal head of Mobility recalled, approximately a quarter of the fleet is already fully electricWith nearly 500 vehicles, Madrid ranks among the European cities with the most zero-emission buses, second only to cities like Berlin. Furthermore, EMT has launched a tender for the acquisition of new 100% electric buses, both standard and articulated, which will be incorporated in the coming years.
This fleet expansion requires continued expanding the charging infrastructure and optimizing the energy management of garages. Therefore, projects such as second-life batteries, along with the deployment of smart charging systems, are considered key to ensuring that the grid can absorb the growth of electric vehicles without skyrocketing costs or overloading the network.
In parallel, EMT is considering the possibility of integrating photovoltaic energy in its facilities, associated with battery storage containers, so that part of the energy used to charge the buses can come directly from renewable generation installed in the garages themselves.
With this approach, the municipal company is not only electrifying its fleet, but is also starting to behave like a active energy actor, capable of managing storage and distributed generation resources in its facilities, in line with the trends being promoted at the European level.
The combination of electric buses, smart charging systems and reused batteries in the depots is allowing EMT Madrid to move towards an urban mobility model cleaner, more efficient and consistent with the principles of the circular economyThe Fuencarral pilot project demonstrates that batteries can continue to offer a useful service beyond their life in vehicles, helping to contain costs, reduce waste and reinforce the role of public transport as the backbone of a more sustainable city.