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GRID4CITY

Selected for funding
Project
Category
Project
Call
DUT Call 2025
Duration
–
Project coordinator
TU Delft

European cities are facing increasing pressure to decarbonize energy and mobility systems while maintaining energy security, affordability, and grid reliability. At the same time, the rapid growth of renewable energy generation, electric vehicles, electrified public transport, and new electricity demands is causing significant grid congestion and creating costly requirements for reinforcement of existing electricity networks. Many cities possess extensive urban DC traction grids for trolleybuses and trams, yet these infrastructures remain largely underutilized outside their transport function. GRID4CITY addresses the challenge of transforming these isolated transport electricity networks into integrated energy-sharing platforms that can support the development of Positive Energy Districts (PEDs). The project specifically tackles:

  • Grid congestion and limited network capacity, which increasingly restrict the connection of new renewable energy systems, EV charging infrastructure, and electrified urban services.
  • Insufficient flexibility in urban energy systems, resulting in difficulties balancing variable renewable generation and fluctuating electricity demand at the district level.
  • Underutilization of existing urban DC traction infrastructure, which currently operates primarily for public transport despite having significant potential to act as an energy backbone for local energy systems.
  • Lack of integrated solutions combining renewable generation, energy storage, electric mobility, and buildings, particularly under real urban operating conditions and within Positive Energy Districts.
  • Energy security and resilience challenges, including vulnerability to supply disruptions, geopolitical risks, and increasing dependence on centralized electricity infrastructure.
  • The absence of mature local energy market models, peer-to-peer energy trading mechanisms, and governance frameworks capable of enabling fair participation of citizens, municipalities, public transport operators, and local businesses in decentralized energy systems.
  • Social and economic barriers to energy transition, including limited citizen engagement, uneven distribution of benefits, uncertainty regarding regulatory frameworks, and the need to ensure that new PED solutions create value for local communities and economies.


The central research question of GRID4CITY is how existing urban DC traction grids can be repurposed as resilient, flexible, and socially inclusive energy-sharing platforms that enable large-scale integration of renewable energy, local storage, electric mobility, and energy communities, while improving energy security, grid resilience, market functioning, and socio-economic outcomes within Positive Energy Districts.
 

GRID4CITY will repurpose existing urban DC traction grids into integrated energy-sharing platforms connecting photovoltaic systems, electric vehicles, buildings, second-life batteries, supercapacitor storage, and public transport infrastructure. The project will work on the following:

  • A Traction-to-Building (T2B) Energy Hub enabling bidirectional energy exchange between traction infrastructure and buildings.
  • Demonstration of mobile chargers for zero-emissions construction machinery in and evaluating the future role of Distribution System Operators (DSOs) together with Traction Grid Operator (TCGO) via multi-commodity approaches
  • Integration of renewable energy generation, particularly PV systems, into urban traction networks.
  • Shared district energy storage based on second-life bus batteries, mobile batteries, and supercapacitors.
  • AI-based Energy Management Systems (EMS) and a Multi-Energy Digital Twin for predictive optimization and real-time control.
  • Local flexibility markets, peer-to-peer (P2P) energy trading, and energy-community models.
  • Citizen-centered governance through an Urban Energy Covenant and Community Energy Command Centers.

The project will be validated through two living labs:

  • Gdynia (Poland): Demonstration of a Traction-to-Building microgrid at the PKT trolleybus depot integrating PV, second-life batteries, regenerative braking energy, and smart energy management.
  • Arnhem (Netherlands): Demonstration of mobile charging solutions for zero-emission construction machinery using the trolleybus network as an energy source. 
     

GRID4CITY will demonstrate how existing urban DC traction grids can be transformed into multifunctional energy-sharing platforms for Positive Energy Districts (PEDs), integrating photovoltaic (PV) generation, electric vehicles, smart charging, vehicle-to-grid (V2G) services, mobile and stationary hybrid energy storage, and advanced power electronics into existing urban infrastructure. Through real-life demonstrations in Arnhem and Gdynia, the project will validate new technical, digital, social, and market solutions that strengthen urban energy systems while creating positive socio-economic impacts. Expected results include:
 

  • Improved energy security and renewable energy integration through the deployment of PV systems, second-life battery storage, hybrid supercapacitor storage, and smart energy management, enabling increased local renewable energy self-consumption and reducing dependence on congested electricity networks.
  • Enhanced grid resilience and flexibility through coordinated operation of distributed energy resources, V2G-enabled electric vehicles, In-Motion Charging (IMC) batteries, shared district energy storage systems, and AI-based energy management. The project aims to increase local flexibility through peak shaving, load shifting, and demand response by approximately 25-50%.
  • Reduced grid congestion and avoided infrastructure investments by leveraging existing traction infrastructure as a local energy-sharing platform. The project will demonstrate at least 10% avoided or deferred grid reinforcement costs through flexibility services, local balancing, peer-to-peer energy exchange, and smart charging strategies.
  • Improved grid stability and power quality through advanced power-electronics converters, a Traction-to-Building (T2B) Energy Hub, Digital Twin-based optimization, and AI-supported control of energy flows between traction networks, buildings, storage systems, and renewable energy assets.
  • Creation of local energy markets and energy communities by implementing peer-to-peer (P2P) energy trading mechanisms, local flexibility markets, innovative pricing schemes, and governance frameworks that enable citizens, SMEs, municipalities, and public transport operators to participate in local energy ecosystems.
  • Development and validation of digital solutions, including a multi-energy Digital Twin, AI-based Energy Management System (EMS), and GRID4CITY Console for real-time visualization, forecasting, optimization, and management of energy and mobility assets. The project also aims to improve digital maturity and Smart Readiness of participating districts.
  • Increased citizen engagement and social acceptance through co-created Urban Energy Covenants and Community Energy Command Centers. The project expects to engage 1,000-1,800 citizens and support the participation of at least 100 households and SMEs in flexibility, energy-sharing, or reward-based energy programs.
  • Positive socio-economic impacts through reduced energy costs, improved energy affordability, new business models, local job creation in energy services and infrastructure retrofitting, and stronger local economic participation in renewable energy markets.
  • A scalable European replication framework, including a Replication Toolkit and City Readiness Index, enabling other cities to adopt traction-grid-based Positive Energy Districts and replicate the demonstrated solutions beyond Arnhem and Gdynia.

Overall, GRID4CITY will provide evidence that urban traction grids can evolve from transport infrastructure into resilient, citizen-centered energy platforms that support renewable energy integration, local energy markets, grid resilience, and climate-neutral urban development. 
 

Participating countries

Latvia

The Netherlands

Poland

Romania

Switzerland

Ukraine

Funded project partners

Delft University of Technology, Gdańsk University of Technology, Riga Technical University, HAN University of Applied Sciences, University Politehnica Timisoara, Bern University of Applied Sciences, PKT Gdynia, City of Gdynia

Other project partners

Municipality of Arnhem, Lviv Electrotrans, Connectr – Energy Innovation, Societatea de Transport Public Timișoara (STPT)

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