Reinforcing the Resilience of Underground Secondary Substations

OVERVIEW

A2A, the Seeker for this Wazoku Crowd Challenge, is looking to identify scalable and practical solutions that could be implemented on a short timeframe to better protect urban electrical infrastructure from the growing risks of flooding.

Secondary substations, whether above ground, underground, or a mixture, are a critical part of A2A’s infrastructure, ensuring uninterrupted power supply in communities across the world. However, frequent flooding and severe weather incidents can affect the performance of these services – both from specific events and from longer-term degradation of performance.

A2A’s interest is in cost-effective, durable, and quick-to-implement solutions that are compatible with their existing infrastructure – helping to combat water ingress into the substation, mitigate the impact of flooding, and/or help to remove excess water from the substation or from damaging critical components.

This Challenge invites proposals from individual Solvers, teams, and start-ups/organizations to address these pressing climate resilience issues with practical, scalable, and quick to implement solutions.

 

Your IP Rights are protected in this Prize Challenge; A2A must award you to obtain them.

The best solution has the opportunity to win the award of $25,000 for meeting all must have solution requirements. This Challenge requires a written proposal to be submitted and Awards will be contingent upon the theoretical evaluation of the proposal by A2A against the Solution Requirements.

To receive an Award, Solvers are required to assign exclusive rights to the Intellectual Property (IP) in their proposed solution. Solvers will retain all rights to any proposal not Awarded.

Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on March 17th, 2025.

Please review the later Participation Guidance section before submitting a proposal.

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ABOUT THE SEEKER & ELIGIBILITY

The A2A Group is the largest Italian multi-utility, at the forefront of territorial services and technological solutions. We design smart and sustainable cities, with respect for the citizens. A2A is at the forefront of energy transition, implementing principles of circular economy in all our activities. With a far-reaching strategic plan, we manage the generation, sale and distribution of electricity and gas, district heating, waste collection and recovery, e-mobility, public lighting, and the integrated water services.

Unareti is the company within the A2A Group responsible for the distribution of electricity and gas, managing the networks and infrastructure essential for the transportation and delivery of these services to end customers. It oversees the management and maintenance of infrastructures, including meters, cabling, and secondary substations, ensuring safety, reliability, and technological innovation in the service.

Unareti plays a key role in addressing challenges related to the resilience of energy infrastructures, such as those caused by extreme weather events. It is also pivotal in the energy transition, integrating innovative solutions for smart and sustainable grids. For this reason, it is the primary stakeholder in the challenge, which aims to prevent and mitigate electrical service disruptions caused by events like the flooding of secondary substations.

 

THE CHALLENGE

BACKGROUND

Flooding incidents in urban environments have seen a steep rise in frequency and severity due to the intensification of extreme weather events and the increasing impermeability of cityscapes. According to the European Environment Agency (EEA), annual precipitation patterns in regions like Northern Italy have become more erratic, with both prolonged droughts and intense rainfall events occurring more frequently.

In the Lombardy region, in particular in the city of Milan, between 2020 and 2024, more than 500 flooding events were recorded that affected hundreds of secondary substations (also referred to as “SS” throughout), with 75% of the total number of cabins being located underground. These cabins were affected by rainfall that could exceed 60 millimeters (mm) in 48 hours, or 20mm in a single hour.

Secondary underground cabins can be found almost all over the municipal territory of Milan, with a higher concentration in the central areas of the city. Historically, there has always been a lack of suitable space in these areas, both from builders and from the municipal administration. In addition, building regulations have never laid down requirements for the construction of buildings to house secondary electrical substations.

Finally, the central areas of the city have the highest power density requirements per unit area, which often saturates the availability of existing substations.

Figure 1: Distribution of underground substations in the Milan territory.

Flooding of secondary substations is understood to be the event in which there is water inside the building above a height of approx. 30-40 cm.

This phenomenon leads to the Medium Voltage (MV)/Low Voltage (LV) secondary substations being ‘taken out of service’, with the consequent interruption of the supply to a significant number of users. Restoration times can be extremely long due to the operations required to recover the premises and replace damaged materials.

The most important damage and interruptions are mainly caused by flooding of the underground rooms used as substations that host electromechanical equipment. The main causes of flooding are attributable to:

Meteorological events (93%)

• Extreme and/or persistent rainfall
• Infiltration due to rising water tables

Third-party causes (7%) (e.g. public or private pipe breakages)

Figure 2: Number of secondary substation flooding events in Milan.

The phenomenon of flooding appears to be widespread throughout the region and not limited only to the Lambro and Seveso rivers flooding areas. From 2020 to date, the total number of floods is close to 500 recorded events, with a highly variable trend over the years, depending on weather events.
 

Figure 3: Milan rainfall trends in the last 5 years, with persistent and extreme rainfall events highlighted.

Figure 3 highlights the annual variability in rainfall, with 2022 being exceptionally dry and 2024 experiencing intense rainfall events.

The phenomenon of flooding of secondary substations affects the entire municipality:
 

Figure 4: Location of secondary substations throughout the Milan municipality.

A secondary substation is a critical part of electrical infrastructure for the distribution to communities. Its primary function is to transform medium voltage electricity into low voltage, making it suitable for domestic, commercial, or industrial use.

Secondary substations are typically built underground in densely populated urban areas where space constraints prevent above-ground installations. However, this positioning exposes them to a variety of significant risks:

• Meteorological Trends: According to ARPA Lombardia, intense rainfall events in Northern Italy have doubled in frequency over the past two decades, directly correlating with increased flooding in urban areas.
• Urbanization Impacts: High-density urban planning, coupled with insufficient drainage systems, exacerbates the risk of water infiltration into underground infrastructures.
• Aging Infrastructure: Many substations were built decades ago, with inadequate design standards to withstand modern climate risks.
• Hydrogeology: the rise of the water table due to intense rainfall can cause flooding through infiltration into the surrounding soil, especially if the structures are not adequately insulated or sealed. This can compromise drainage systems, increasing the risk of water accumulation inside the substations.

Generally speaking, once inside, water can damage electrical components causing short circuits, loss of insulation, and malfunctions. Residual moisture also poses a risk by accelerating the corrosion of equipment and reducing its lifespan.

These phenomena undermine the continuity of electrical service and result in high maintenance and repair costs, necessitating prevention strategies and timely interventions.

Typical substation’s structure and main components:

Structure

• Building or housing structure:
  • Prefabricated, typically made of concrete, metal, or other durable materials.
  • Provides protection against weather, intrusions, and complies with electrical safety standards.
  • Can be underground, semi-underground, or above ground, depending on location and network needs.
• Internal layout:
  • Divided into areas for high/medium voltage (HV/MV) and low voltage (LV).
  • Dedicated space for monitoring and measurement equipment.
• Size/dimensions:
  • Surface area: approx. 15 to 30 m²
  • Height: between 2.5 and 3 metres
  • Shape: often rectangular or square.
  • Depth: from 2 and 4 metres below ground level

Main Components

1. Transformer
Reduces voltage from medium (typically 15-20 kV) to low voltage (230/400 V). Types include:

• Dry-type: Air-cooled, suitable for indoor environments.
• Oil-filled: Cooled with insulating fluid, commonly used for higher capacities.

2. Medium Voltage (MV) Switchgear: Manages and protects medium voltage connections. Components include:

• Circuit breakers
• Disconnectors.
• Fuses for overload or short-circuit protection.
• Voltage and current indicators.

3. Low Voltage (LV) Switchgear: Distributes electricity to end-users. Components include:

• Protective breakers (magnetothermal, differential).
• Disconnectors.
• Busbars for connecting LV lines.
• Contactors or switching devices.

4. Monitoring and Control System: Enables remote control and monitoring of the substation’s status. Components include:

• Voltage and current sensors.
• SCADA systems for remote control and diagnostics.
• Event and data loggers for performance analysis.

5. Protection Systems: Ensures safety in case of anomalies. Components include:

• Protection relays (for faults, overloads, short circuits).
• Surge protection devices (SPD) to guard against lightning and voltage spikes.

6. Grounding System: Discharges fault currents to the ground, ensuring safety. Components include:

• Grounding bars.
• Connections to the substation’s metallic components.

7. Ventilation and Cooling Systems: Prevents overheating and maintains optimal operating conditions. Types include:

• Fans.
• Natural ventilation systems.

8. Lighting and Accessories: Facilitates maintenance operations by human operators. Components include:

• Internal lights.
• Power outlets for technical equipment.

9. Fire Protection System: Safeguards the substation in case of fire. Components include:

• Automatic or manual extinguishers.
• Smoke and heat detectors.

Operation

The secondary substation receives electrical energy from the medium voltage network and:

• Transforms it via the transformer.
• Distributes it through the LV switchgear to end-users.
• Monitors and protects the system to prevent disruptions or damage.

Standards and Safety

Secondary substations must comply with stringent regulations (e.g., CEI 0-16, CEI EN 50522) to ensure electrical safety, fault protection, and minimal environmental impact.

Figure 5: Construction of cabin entrance wall, with a raised element as a typical mitigation action. Height is 40cm.

Figure 6: Engineer indicating the water height measurement of 70cm, taken post-repair.

Figures 7, 8, and 9: Example cabin entrance via a trapdoor at street level, leading to the cabin located in an abandoned building. Example water height of 80cm.

Substations’ designs, operations, standards and safety can differ, however for the purposes of this Challenge, the above descriptions should be sufficient to plan your submissions to these outlines.

Flooding and water damage incidents to secondary substations can have significant repercussions – both to the functioning of the infrastructure, the operators, and the communities which they serve:

• Disruption of Essential Services: Secondary substations are critical for converting medium voltage (MV) to low voltage (LV), and their failure may result in blackouts or extended electrical power outages to significant numbers of Unareti’s clients, both residential and commercial.
• High Recovery Costs: Flooding damages expensive electromechanical equipment and reduces the system’s efficiency, requiring labour-intensive repairs or expensive replacements. Outside of the financials, there is also a reputational cost for the Provider, as the perceived reliability of the electricity operator may be compromised, reducing customer trust.
• Operational Downtime: Recovery times are prolonged, as water removal and equipment replacement often takes days or weeks.
• Safety risk: Water can increase the risk of electric shocks and, over time, cause equipment failures that may lead to overheating and fires.
• Traffic-Related Disruptions and Limited Accessibility: Flooding of roads or surrounding areas can hinder the timely intervention of maintenance teams, which might also be engaged in addressing other emergencies.

The Italian report "Strategia Nazionale di Adattamento ai Cambiamenti Climatici" highlighted the pressing need for resilient infrastructure, emphasizing the role of local adaptations to address deficiencies or fragilities in urban energy systems. Furthermore, ARERA, the Italian Regulatory Authority for Energy, Networks, and Environment, has also underscored the economic and social impacts of power outages caused by climate events.

The negative impacts caused by electrical service disruptions to end users could also see Unareti penalized by relevant authorities/institutions. Avoiding interruptions would lead to an overall improvement in the service offered to customers, a reduction in maintenance costs, and a mitigative approach to potential fines or redress from authorities.

Current Flood Mitigation Technologies for Substations

A2A and Unareti have to-date already implemented measures to mitigate the risks of flooding and water damage to underground substations. While these actions have provided some level of protection, they have proven insufficient during severe flooding or extreme weather events.

Sensors installed in the field:

Flood detection technologies vary between plants and are not uniform. Generally, there are two types of float switches:

• Water presence: detects when the water level exceeds 4-5 cm and sends a signal to the control room;
• SS flooding: triggered when the water level exceeds 10 cm, resulting in the automatic release of the transformer (“TR”). In some secondary substations, where the disconnection of the TR was not permitted by the type of MV compartment, the disconnection of one of the LV cables was implemented. 

The height of the floats was defined with the aim of enabling timely intervention before the equipment in the cabin was submerged. To date, this logic may not be the most optimal.

In the absence of floats, if the SS is flooded, the MV feeder in SS is triggered, causing the interruption of service even to users not supplied by the cabin affected by the flooding. Currently, Unareti does not employ systems capable of monitoring the water level in the cabin in real time.

Below there is a detailed analysis of the advantages and limitations of the measures currently studied by A2A and Unareti to mitigate flooding risks for underground substations:

1. Thermal Cameras

• Pros:
  • Provide real-time detection of temperature anomalies, which can indicate overheating or potential water damage-related issues.
  • Non-invasive: Detect problems without the need for physical contact.
  • Enable predictive maintenance, helping identify risks before failure occurs.
• Cons:
  • High cost: Requires significant investment for installation and upkeep.
  • Needs regular maintenance and calibration to ensure accuracy.
  • Limited effectiveness on reflective surfaces, which can distort readings.

2. Humidity Sensors and Water Level Indicators

• Pros:
  • Offer continuous monitoring of humidity and water levels, providing critical early warnings.
  • Cost-effective and scalable: Suitable for deployment across multiple substations.
  • Simple integration into existing IoT systems for centralized monitoring.
• Cons:
  • Reliability concerns: Sensors may fail or provide inaccurate readings in extreme conditions.
  • Require regular inspection and replacement to maintain functionality.
  • Can produce false positives in high-humidity environments without actual flooding.

3. Flexible Printed Membranes with LoRaWAN Technology

• Pros:
  • Enable real-time leak detection with wide-area monitoring capabilities via LoRaWAN (long-range wireless connectivity).
  • Low energy consumption: Ideal for long-term deployments in remote locations.
  • Flexible and adaptable to various substation layouts.
• Cons:
  • Technology and use cases are still under investigation: Practical application in substations remains unproven.
  • May have durability issues depending on environmental conditions.
  • Could face interference or connectivity issues in dense urban areas.

4. Innovative Permeable Concrete and Robotic Pumping Systems

• Pros:
  • Dual functionality: Permeable concrete reduces water accumulation, while robotic pumping systems actively remove excess water.
  • Sustainable solution: Reduces dependence on chemical waterproofing materials.
  • Can be integrated into long-term infrastructure upgrades.
• Cons:
  • High cost: Both materials and robotics involve significant initial investments.
  • Absorption capacity: Permeable concrete may not handle extreme flooding scenarios effectively.
  • Application challenges: Retrofitting existing infrastructure can be complex and time-consuming.

5. Flood Barriers

• Pros:
  • Provide modular and robust protection against water ingress.
  • Adaptable designs: Suitable for various substation layouts and environments.
  • Can be deployed quickly during emergencies.
• Cons:
  • Labor-intensive setup: Requires timely intervention to install barriers before flooding occurs.
  • May have limitations against prolonged or extreme flooding, particularly if water levels surpass barrier heights.
  • Storage and maintenance: Barriers require significant storage space and regular inspections to remain effective.

Each of these technologies has unique strengths and weaknesses, and their effectiveness depends on the specific flooding risks, the environment of the substation, and the budgetary constraints for implementation. A combination of these solutions may offer a more comprehensive approach to flood mitigation. The next steps would involve exploring more robust and preventive strategies, such as advanced flood-resistant designs, automated water pumping systems, and predictive modeling to anticipate and prepare for extreme weather events.

Additionally, other proven solutions have included relocating substations above ground (together with municipal administrative bodies’ location of suitable sites), the design and distribution of compact secondary substations, and review of building regulations (to give more consideration to the protection and location of secondary substations and electrical infrastructure in new builds/renovations).

Despite these efforts, severe flooding continues to highlight critical gaps in the resilience of electrical infrastructure. Flooding in September 2024 in Milan affected over 65,000 citizens. As the European Commission's EU Strategy on Adaptation to Climate Change outlines, integrating innovative, localized solutions with existing infrastructure is essential to safeguarding urban energy networks.

However, this specific Challenge is focused on solutions to improve the resilience of underground secondary substations, through mitigation, prevention, and other innovative approaches. While long-term infrastructural changes, such as relocating substations above ground, are recognized for their effectiveness, they are deemed unsuitable for this challenge due to regulatory and implementation delays.

 

THE CHALLENGE

A2A and Unareti are seeking short- and medium-term solutions to address the increasing vulnerability of underground secondary substations to flooding. These substations play a critical role in urban power distribution networks, yet their underground locations put them at risk of water ingress during extreme weather events. Solver’s solutions should focus on enhancing the resilience of existing infrastructure through prevention or mitigation while aligning with practical and financial constraints.

Unareti and A2A have found some success with previously-listed mitigation methods, but to fully prevent and mitigate the impacts of flooding, innovation and new approaches are required to safeguard underground secondary substations. The suggested combination or innovative applications of previously-attempted methods would also be supported, however A2A and Unareti are also open to novel methods.

Given the urgency to implement scalable actions in the short term to address severe weather events and flooding, this challenge seeks innovative solutions to reinforce and revolutionize the resilience of underground secondary substations.

Some approaches of interest could include, but are not limited to:

• Advanced sealing methods
• Flood-resistant materials
• Innovative architectural designs for retrofitting existing substations
• Rapid water extraction through advanced pumping technologies.
• Designs/layouts that minimize damage by redirecting floodwater away from critical components
• Solutions/sensors that inform A2A of both water presence and the level reached by the water, as well as whether it is increasing or decreasing in a certain time frame
• 3D digital twins of secondary substations for predictive analysis
• IoT or AI-driven tools for flood prediction and response
• Innovative permeable paving technologies for use within the substation flooring
• Temporary/modular solutions, such as mobile flood barriers or event-based pumping systems
• Novel drying systems
• Solutions that could integrate with urban systems, including city-level flood management and monitoring, drainage infrastructure, or emergency services

This A2A Challenge calls for the Wazoku Crowd to bring innovative technologies and methodologies that address the shortcomings of existing solutions, ensuring the resilience of urban electrical infrastructure in the face of increasing climate challenges.

Any solution, approach, or commercial product should effectively mitigate or prevent the risks of flooding in underground secondary substations, while reducing downtime, preventing/lessening repair costs or frequency of repair, and improving the reliability of services provided to end-users.

 

SOLUTION REQUIREMENTS

A2A is primarily interested in solutions with the potential to meet the following requirements:

Must have:

1. Effective flood prevention and/or mitigation solution
   • Prevention: preventing water ingress to the underground substation, through improved sealing, resilience, or novel designs/layouts.
   • Mitigation: ways to limit damage to components such as redirecting floodwater/protecting critical parts of the infrastructure; methods to remove the water after it has entered the substation; or other mitigative approaches that ensure good operation through event-based flooding or its long-term effects.
2. Cost-effective approaches with room for scalability
   Solutions must be affordable and feasible for A2A and Unareti to implement at scale, addressing multiple substations types and sizes.
3. Quick to implement
   To address rising flooding incidents, it is desired that your solution can be implemented in substations within the short- to medium-term (6 months to 1 year). This can depend on the complexity of the solution, as well as A2A’s feasibility for quick testing to see its field efficacy.
4. Durability and Reliability
   Solutions should perform effectively over time and over several flooding incidents (not single use) and require minimal ongoing maintenance, ensuring long-term resilience.
5. Compatibility
   Solutions must integrate with existing substation designs as described in the Background, and with traditional electrical infrastructure technologies without requiring complete overhauls.

Additionally, your solution could address the following nice-to-have approaches and criteria:

1. Prototype demonstrations or proof of concept data
   While this Challenge will be based on theoretical evaluation by A2A and Unareti staff, if you have prototypes or data/use cases proving your solution’s applicability to this Challenge, please provide details or willingness to discuss details with evaluators. If your solution is a commercial product already available on the market, demonstrations or case studies would be of interest to evaluators.
2. Sustainability and circularity
   Use of environmentally-friendly materials or approaches that align to A2A’s wider sustainability goals. Recyclable materials, energy-efficient technologies, or innovative equipment would be of interest.
3. Applicability to other urban infrastructure
   While this Challenge’s focus is on improving the resilience of underground secondary substations, if effective and successful, your solution’s applicability to improving the flood resistance and resilience of other urban, underground infrastructure would be of interest.

Things to Avoid:

• Relocation of Substations Above Ground
  While effective, this solution is already part of A2A and Unareti’s long-term strategies and faces significant spatial and administrative blockers in dense urban areas. The timeline for above-ground relocation of substations often spans multiple years and several layers of regulatory approval with municipal bodies, making it unsuitable for addressing immediate risks.
• High-Cost, Non-Scalable Solutions
  Proposals requiring significant financial investment without clear scalability across multiple substation types will not be prioritized.
• Disruptive Implementations
  Solutions that would require extended downtime of substations or significantly disrupt urban activities during implementation are less desirable, given the urgency of maintaining continuity of service.
• Purely Predictive Tools Without Preventive or Mitigative Measures
  While monitoring and forecasting are valuable, standalone predictive solutions do not sufficiently address the challenge of minimizing damage and service interruptions. For instance, a sensor indicating the presence of water is interesting only when it is combined with the ability to communicate the level of the water in the substation, or whether it has increased or decreased within a certain timeframe.

Solutions with Technology Readiness Levels (TRL) 6-9 are invited.

This Prize Challenge has the following features:

• The best solution has the opportunity to win the award of $25,000 USD for meeting all must have solution requirements, as solely determined by A2A.
• Your IP Rights are protected in this Prize Challenge; A2A must award you to obtain them.
• This Challenge requires a written proposal to be submitted and Awards will be contingent upon the theoretical evaluation of the proposal by A2A against the Solution Requirements.
• To receive an Award, Solvers are required to assign exclusive rights to the Intellectual Property (IP) in their proposed solution.
   

YOUR SUBMISSION

Please login and register your interest, to complete the submission form.

Please note, A2A requires all Solver proposals to include the following:

• Technical documentation: a detailed explanation of the solution’s operation and effects, schematics, materials, and mechanisms.
• Implementation plan: a phased plan that outlines the steps required for deployment by A2A, including timelines and resources required.
• Feasibility study: where possible, an analysis of the solution’s scalability, cost-effectiveness, and compatibility with existing substation designs.
• Impact assessment: an evaluation of the expected reduction in impact of floods and adverse weather events. This could include metrics such as reduction in substation downtime, reduction in repair costs/maintenance time, and improvements in overall service reliability.
  Additionally, if your solution is mature or market ready, it would also be of interest if you could provide details around:
• Prototypes or proof of concept: if applicable, include details and evidence of your prototypes or case studies demonstrating successful implementation of your solution in similar contexts.

The submitted proposals must be written in English and can include:

1. Participation type – you will first be asked to inform us how you are participating in this challenge, as a Solver (Individual) or  Solver (Organization).
2. Solution Level - the Technology Readiness Level (TRL) of your solution.
3. Problem & Opportunity - highlight the innovation in your approach to the Problem, its point of difference, and the specific advantages/benefits this brings (up to 500 words).
4. Solution Overview - detail the features of your solution and how they address the SOLUTION REQUIREMENTS (500 words, there is space to add more in the summary field, and attach supporting data, diagrams, etc). This Challenge’s specific solution requirements include the need for technical documentation about your submission.
5. Solution Feasibility – Supporting Information and Rationale, such as references and precedents, that will help A2A evaluate and validate the feasibility of the solution (up to 500 words). This can include:
   • Feasibility study
   • Impact assessment
   • Prototype/PoC details, if applicable – for Solvers submitting high TRL submissions.
   • Commercial market examples of use, if applicable – for Solvers submitting mature products.
6. Experience - Expertise, use cases and skills you or your organization have in relation to your proposed solution.  (up to 500 words).
7. Solution Risks - any risks you see with your solution and how you would plan for this (up to 500 words).
8. Timeline, capability and costs - describe what you think is required to deliver the solution, including implementation plan, estimated time and cost (up to 500 words).
9. Online References - provide links to any publications, articles or press releases of relevance (up to 500 words).

 

PARTICIPATION GUIDANCE

1. Submission Close Date: Submissions to this Challenge must be received by 11:59 PM (US Eastern Time) on March 17th, 2025.
2. Late submissions: Late submissions will not be considered.
3. Multiple submissions, 3 Maximum: In case of multiple submissions by the same Solver, only 3 submissions – the final 3 submitted – will be considered. Any other submissions will be deleted prior to evaluation.
4. Submission form and attachments: Your submission will be evaluated by the evaluation team first reviewing the information and content you have submitted at the submission form, with attachments used as additional context to your form submission. Submissions relying solely on attachments will receive less attention from the evaluation team.
5. Evaluation notification steps: After the Challenge submission close date A2A will complete the review process and make a decision with regards to the winning solution(s) according to the timeline in the Challenge header. All Solvers who submit a proposal will be notified about the status of their submissions.
6. Use of AI: Please note that any submissions produced solely with generative AI are not of interest.
7. Learn more: Find out more about participation in Wazoku Crowd Challenges.