Critical Dependency Mapping in Electricity Systems

Detailed Explanation With Case Laws

1. Introduction

Critical dependency mapping in electricity systems means identifying the infrastructure, services, technologies and organisations that an electricity system depends upon for its safe and continuous operation. It also examines which other systems depend on electricity.

Modern electricity networks are not isolated. They depend on fuel supplies, telecommunications, digital systems, water, transport, skilled workers and physical infrastructure. At the same time, hospitals, water utilities, railways, banking systems and communications networks depend on electricity.

Therefore, dependency mapping helps identify cascading risks before they become major electricity emergencies.

2. Meaning of Critical Dependency

A dependency exists when the operation of one system requires another system.

For example:

Electricity grid → telecommunications → control centre

If telecommunications fail, operators may lose important monitoring or control functions.

Another example is:

Electricity → water pumping → public water supply

If electricity is unavailable for a prolonged period, water services may also be affected.

A critical dependency is one where failure could seriously affect electricity-system security or essential public services.

3. Main Dependencies of Electricity Systems

Electricity systems have several important dependencies.

Fuel Dependency

Gas-fired generators depend upon reliable gas supplies.

Telecommunications Dependency

Grid operators require communication networks for monitoring and operational control.

Water Dependency

Some electricity-generation facilities require water for cooling or other processes.

Digital Dependency

Modern grids rely on software, SCADA systems and digital protection equipment.

Transport Dependency

Maintenance teams require roads, railways and other transport systems to reach damaged infrastructure.

Human Dependency

Electricity systems depend upon skilled engineers, control-room personnel and emergency workers.

4. Electricity as a Dependency for Other Systems

The relationship also operates in the opposite direction.

Electricity supports:

hospitals;

water treatment;

telecommunications;

airports;

railway systems;

financial services;

food supply chains;

emergency services; and

data centres.

This creates two-way dependencies.

For example:

Electricity → telecommunications

but also:

Telecommunications → electricity-grid operation.

This makes dependency mapping more complex than simply identifying electricity consumers.

5. Purpose of Dependency Mapping

The main objectives are to:

identify critical infrastructure;

identify single points of failure;

understand cascading risks;

support emergency planning;

improve network resilience;

guide investment decisions;

improve cybersecurity;

support regulatory coordination; and

protect essential public services.

A dependency map therefore provides a risk picture of the electricity system.

6. Cascading Failure

The most important reason for dependency mapping is the possibility of cascading failure.

For example:

Major substation failure

↓

Regional electricity outage

↓

Telecommunications systems lose power

↓

Emergency communications are disrupted

↓

Water pumping is affected

↓

Hospitals face additional operational difficulties

The original problem may therefore spread beyond the electricity sector.

Dependency mapping allows authorities to identify such chains in advance.

7. Critical National Infrastructure

The UK treats energy as part of Critical National Infrastructure (CNI).

The Government's response following the North Hyde electricity incident specifically considered how energy infrastructure interacts with other CNI sectors and supported work to improve understanding of these dependencies.

This demonstrates an important change in infrastructure regulation.

The focus is moving from:

“Is this electricity asset protected?”

towards:

“What other systems depend on this asset, and what does this asset depend on?”

8. Electricity Supply Emergency Code

The Electricity Supply Emergency Code (ESEC) is particularly relevant.

It provides arrangements for serious electricity-supply emergencies and establishes a Protected Sites List.

The Code gives special consideration to infrastructure whose loss could affect:

energy-system security;

human life;

public health;

essential services;

national security; and

critical industrial processes.

This is an example of dependency-based regulation.

If an electricity facility is essential to maintaining another critical service, its importance may increase during emergency planning.

9. Grid and Telecommunications Dependency

Modern electricity networks rely heavily on telecommunications.

Operators use communications for:

system monitoring;

protection;

remote control;

operational instructions;

fault information; and

emergency coordination.

Therefore, a telecommunications outage can become an electricity-system risk.

This creates a legal and regulatory need for:

backup communications;

independent communication channels;

emergency procedures;

cybersecurity protection; and

resilience testing.

10. Cybersecurity Dependency

Digitalisation has created another important dependency.

Electricity systems increasingly use:

SCADA;

remote terminal units;

digital substations;

automated protection;

cloud services;

data platforms; and

remote-access systems.

A cyber incident may therefore affect physical electricity operations.

Dependency mapping should identify:

digital system → electricity function → possible consequence.

This is especially important where several grid functions depend upon the same digital provider.

11. Fuel and Gas Dependency

Gas-fired electricity generation provides another example.

A power station may be operationally ready but unable to generate electricity if its gas supply is interrupted.

Therefore, electricity-security planning may need to consider:

gas pipelines;

gas storage;

fuel availability;

transport capacity;

supplier resilience; and

emergency fuel arrangements.

The electricity and gas systems must therefore be considered together in certain risk assessments.

12. Dependency Mapping and Network Planning

Dependency mapping can influence electricity-network investment.

Suppose a substation supplies:

a hospital;

water-treatment plant;

telecommunications facility; and

transport infrastructure.

That substation may have greater resilience importance than a similar substation serving less critical demand.

Investment decisions could therefore consider:

alternative supply routes;

backup transformers;

local generation;

battery storage;

automatic switching; and

enhanced physical security.

Thus, dependency mapping can support risk-based infrastructure investment.

13. National Security and Investment Act 2021

The National Security and Investment Act 2021 also has relevance.

The legislation provides powers to scrutinise certain acquisitions that may create national-security risks in sensitive sectors, including specified energy activities.

Dependency mapping can help demonstrate why a particular electricity asset is strategically important.

For example, control of an important electricity facility may indirectly affect:

water;

communications;

transport;

healthcare; and

emergency services.

Therefore, the importance of an asset may extend beyond its immediate electricity function.

14. Relevant Case Law: SSE Generation v CMA

R (SSE Generation Ltd) v Competition and Markets Authority [2022] EWCA Civ 1472

This Court of Appeal case concerned electricity transmission charging arrangements and the interaction between industry arrangements and statutory regulatory duties.

The case is relevant to dependency mapping because it demonstrates that technically complex electricity arrangements must operate within a lawful statutory framework.

A regulator cannot rely solely on technical necessity when exercising regulatory powers.

For dependency regulation, this means that information-sharing, resilience or emergency obligations should have an appropriate legal foundation.

15. Relevant Case Law: National Grid v GEMA

R (National Grid Electricity Transmission plc) v Gas and Electricity Markets Authority [2018] EWCA Civ 1344

This case concerned electricity transmission regulation.

Its wider importance is that complex technical decisions made by an energy regulator remain subject to statutory requirements and judicial review.

This principle is relevant where regulators use dependency information to make decisions concerning:

network investment;

security standards;

system operation; or

emergency arrangements.

Technical expertise must therefore be combined with lawful and accountable decision-making.

16. Resilience Requirements

Dependency mapping should lead to practical measures.

Electricity operators may need:

backup generators;

alternative control centres;

redundant telecommunications;

spare transformers;

emergency fuel;

cyber incident-response plans;

physical security;

emergency personnel; and

restoration procedures.

The ESEC also makes clear that protected-site status does not itself guarantee continuous electricity supply. Sites should consider their own resilience measures, including standby generation and business-continuity arrangements.

17. Information Sharing and Confidentiality

Effective mapping requires information from several organisations.

These may include:

transmission operators;

distribution network operators;

generators;

gas companies;

water companies;

telecommunications providers;

hospitals;

emergency services; and

government authorities.

However, detailed dependency information can be security-sensitive.

For example, publishing the exact location of critical control systems or backup communication routes could create additional risks.

Therefore, the law must balance:

information sharing + regulatory transparency + confidentiality + national security.

18. Legal Challenges

Responsibility

It may be difficult to determine which organisation is responsible when a failure crosses several sectors.

Cost Allocation

One company may have to invest in resilience even though several sectors benefit.

Data Protection

Detailed operational information may require controlled access.

Cybersecurity

Dependency maps themselves can become attractive targets for cyberattacks.

Changing Technology

Dependencies change as the electricity system becomes more digital and decentralised.

19. Future Importance

Dependency mapping will become increasingly important because of:

renewable generation;

battery storage;

electric vehicles;

electric heating;

smart grids;

artificial intelligence;

cloud computing;

distributed energy resources; and

increasing digitalisation.

As electricity becomes more important to other sectors, electricity-system dependency becomes a central issue of infrastructure resilience.

20. Conclusion

Critical dependency mapping in electricity systems is the process of identifying what the electricity system depends upon and what other essential services depend upon electricity.

The central chain is:

Identify dependency → assess consequence → identify cascading risk → establish resilience → monitor and review.

The UK's treatment of energy as Critical National Infrastructure and the Government's work following the North Hyde incident demonstrate the increasing importance of understanding cross-sector dependencies.

The Electricity Supply Emergency Code further demonstrates how electricity infrastructure and essential services can receive special consideration during supply emergencies.

Cases such as SSE Generation v CMA [2022] EWCA Civ 1472 and National Grid v GEMA [2018] EWCA Civ 1344 show that even highly technical electricity regulation must remain within lawful statutory powers.

For PhD-level energy-law analysis, the key point is that electricity resilience cannot be assessed by looking at the grid alone. Effective regulation must examine the wider network of dependencies involving gas, telecommunications, water, transport, digital systems and essential public services. Dependency mapping therefore provides an important legal and regulatory tool for preventing a local electricity failure from becoming a wider societal crisis.