Written evidence submitted by Energy Networks Association


About ENA

Energy Networks Association (ENA) represents the owners and operators of licenses for the transmission and/or distribution of energy in the UK and Ireland. Our members control and maintain the critical national infrastructure that delivers these vital services into customers’ homes and businesses.


ENA’s overriding goals are to promote UK and Ireland energy networks ensuring our networks are the safest, most reliable, most efficient and sustainable in the world. We influence decision-makers on issues that are important to our members. These include:

As the voice of the energy networks sector, ENA acts as a strategic focus and channel of communication for the industry¹. We promote interests and good standing of the industry and provide a forum of discussion among company members.

Our members and associates

Membership of Energy Networks Association is open to all owners and operators of energy networks in the UK.

     Companies which operate smaller networks or are licence holders in the islands around the UK and Ireland can be associates of ENA too. This gives them access to the expertise and knowledge available through ENA.

     Companies and organisations with an interest in the UK transmission and distribution market are now able to directly benefit from the work of ENA through associate status.


ENA members


This document sets out the response to the Joint Committee on the National Security Strategy (JCNSS) Call for Evidence[1] on critical national infrastructure and climate change adaptation on behalf of gas and electricity transmission and distribution network operators. While not all gas and electricity networks are classified as Critical National Infrastructure, they can be considered critical to the normal operation of society.

Please note that this response is on-behalf of gas and electricity transmission and distribution network operators only, and does not include those of generators or suppliers. As directed, we have only responded to the key issues applicable to the gas and electricity transmission and distribution network operators.


Key vulnerabilities and levels of preparedness


Climate Change impact vulnerabilities

ENA has recently completed a co-ordinated gas and electricity transmission and distribution network operators’ adaptation report for DEFRA. The report reviewed the potential climate change risks that could impact on the networks in the short, medium and longer term.


The main impacts on gas and electricity networks from the latest independent Met Office UKCP18 climate change projections remain:


How key climate change risks impact on network operator assets are set out below:


Regardless of the source, the impact of flooding on ground located assets is the same. Plant and equipment is physically damaged by flood water, but water ingress will also cause electrical faulting and gas supply quality and pressure related issues within the assets and the network leading to extensive loss of supply. Increased rainfall also leads to increased fluvial flow erosion to riverbanks, potentially removing the ground material support to cables and gas pipes and exposing them. This is a particular risk at river crossing points. Consequential repair or replacement of assets is costly and time-consuming, extending restoration of supply times to local areas. Network operators will often choose to switch out plant and equipment in order to avoid water ingress causing a fault and uncontrolled shut down.


The impact of rises in temperature can already be seen in the increased sag of overhead electricity lines, prompting some network operators to increase the height of the poles supporting impacted circuits. High temperatures also impact on the operational efficiency and life-span of transformers and switchgear, increasing the potential for failure. However, as with gas assets, electricity assets are designed to international standards and are generally able to operate in temperatures higher than those predicted for the UK in the climate change scenarios.

Increasing temperature impacts all gas plant and equipment, and increases could affect rating and asset performance. However, gas equipment is inherently resilient and designed to operate at high temperatures in excess of any expected average increase and there should be minimal impact on the gas network controls.


As we have seen recently, storms (in particular those with high wind speeds), can have a significant impact on electricity networks, with falling trees and wind-blown debris damaging, in particular, overhead lines and supporting poles. ‘Icing’ of overhead lines due to snow and moisture in the air from storms with particularly cold air is also a problem, as it can lead to extreme loading of conductors and ultimately failure. Storms often bring both cold weather and high winds, compounding the issues. Loss of overhead lines leads directly to loss of power to customers fed by those lines, and replacement of these lines is key in re-establishing power supplies following a storm event.


Compound Effects

Energy network operators have identified that the combination of high winds following prolonged wet weather periods pose the highest risk to their operations. Prolonged rain or flooding can soften the ground, weakening the support to overhead line poles and to trees, if this is followed immediately by strong winds the additional load can cause poles to topple and bring lines into contact with the ground or trees to be uprooted. Falling trees and wind-blown debris are the main causes of damage to the overhead line network.

Compound effects can also lead to ground and river erosion leading to exposure of damage to underground pipes and cables.



Energy network operators are aware of other utilities relying on, in particular electricity, in order to operate. Gas network operators rely on electricity to operate pumps and controls, and without it full control and operability of the gas supply cannot be maintained. However, the majority of key gas plants will have installed back up generation in order to maintain operation.

Key concerns by energy network operators are utilities that rely on electricity to operate but have no or minimal back up plans; it has been noted that some industries have assumed electricity will be available as part of their operational resilience plans, in particular telecommunications and broadband providers. As such, a loss of power may result in telecommunications and broadband disruption leading to challenges in communicating with emergency services.

While many priority services, including some hospitals, care homes and utility operators, have emergency generation back-up it is important that regular checking and testing is undertaken to ensure the generation activates when called upon. It is also important to consider the availability and accessibility of fuel to run generators during a major power outage. 


Supply Chain

All energy network operators hold strategic spares at stores throughout their operational areas. These spares are sufficient to restore supplies and repair damaged equipment, but there is a risk that these supplies could run low during prolonged or repeating severe weather events, especially where suppliers and/or transport links are also impacted by the events or where specialist equipment has long delivery lead times.


Recent near miss scenarios

We refer the Committee to the Department for Business, Energy and Industrial Strategy’s interim report on the effects of Storm Arwen (publication tbc).


“Acceptable” level of resilience


Before determining what an acceptable level of resilience is, it needs to be made clear how resilience would be measured and compared across UK CNI and UK plc.

With storms becoming more frequent due to climate change, the Met Office lists 50 named storms to date since the start of the 2015/16 season, with a third of those occurring since 2019. Hence continued investment and innovation in network resilience, and better working with local resilience forums to support communities during emergencies, is crucial.

In the past five years, the six GB distribution network operators (DNOs) have spent around £12bn in measures that support increased reliability and resilience. Over the coming five years (the next regulatory period), this is forecast to increase by around 20% subject to approval by the industry regulator, Ofgem.

The energy network operators regularly review the impact of climate change on weather patterns and severity and are implementing options for minimising the disruption caused by storms, floods and temperature rise. The tipping point will be when the efficiency of the current approaches are shown to be reducing. We currently all work to agreed industry standards for resilience, for example the maximum wind speed for overhead lines poles. We need to agree as a society what an acceptable level of resilience is; we encourage open discussion and engagement to better understand how resilience standards can adapt to continue to protect CNI in the future, the costs that would be incurred to achieve these standards and how these should be spread in a way that is fair to consumers.

The electricity networks operate around 300,000km of overhead lines in the UK, and the cost to undergrounding all of these will be very significant. ENA is eager to work with government, Ofgem, customers and industry to discuss and agree a suitable level of resilience.


Effectiveness of Government policy, legislation and implementation frameworks


Government has a critical role to play in managing national security risks arising from climate change. We see that Net Zero, mitigating and adapting to climate change is a key focus of Government departments and associated bodies such as the Committee on Climate Change and the National Infrastructure Commission. We welcome the Second National Infrastructure Assessment process by the NIC, and the intended focus on resilience and climate adaptation.

In terms of networks, in the past five years, the six GB DNO companies have spent around £12bn in measures that support increased reliability and resilience. We want to work with Government, Ofgem, Customers and Industry to discuss a suitable level of resilience and the subsequent level of investment needed to support it.


Allocation of roles and responsibilities at the national, devolved and local level


Improved collaboration across industry, government, regulators, Nationalnational, devolved and local level entities need to work together to ensure the resilience of the energy system. A single point of coordination across the energy sector is required to strategically manage emergencies and understand resilience. Networks are, by their nature, highly local, so local Gas and Electricity Networks have a key role to play in their areas, alongside other relevant bodies.Nationally, ENA facilitates the Single Emergency Number 105, the NEWSAC agreement and various resilience related engineering standards on behalf of Members. National co-ordination is key to ensuring consistency, sharing of resources and common standards.


Government National Resilience Strategy


ENA responded to the consultation on the Government National Resilience Strategy in September 2021, where we provided extensive documentation and information regarding the existing policies, procedures and standards developed and used by the energy network operators in their emergency planning and restoration works and the use of Cabinet Office Security Risk Assessments.


We supported the principles of the GNRR and the setting clear of standards for resilience would help government, regulators, and industry in clarifying resilience outcomes that government wants to see achieved. Government should also consider the capacity to respond by different industry bodies as well as seeking to understand the perception of resilience at a national and local (regional) level and the responses that are required to each set of incidents.


Effectiveness of UK-wide monitoring and early warning systems


Network operators rely on receiving warnings of severe weather as early as possible in order to plan their emergency response and to move resources to areas at risk from impact. The earlier and more accurate these warnings can be given the longer the network operators have to fully plan and ensure that societal support is provided where it is required.

There has recently been an update in research data available used to predict the possible impacts of different climate change scenarios. It is important that research continues into the long-term trends and impacts of climate change and that this is fed back to CNI operators and network operators.


Opportunities presented by technological solutions


We believe that technological solutions such as AI and digital twins, as well as innovation in the resilience space more generally, will be very important in improving our anticipation and management of the implications of climate change for CNI. Our Members currently undertake a range of innovation projects with respect to resilience of networks, and this will continue in the next regulatory period. These innovation projects can be seen on the ENA Smarter Networks Portal[2].

National Grid ESO is currently working with industry to develop the Virtual Energy System[3] – a world first, real-time replica of their entire energy landscape that will work in parallel to their physical system. This will afford a virtual environment through which data, model and test scenarios can be shared to make decision-making more robust. It can identify how different technologies and infrastructure will affect the whole energy system, allowing improved coordination, adaption and planning in a changing environment and climate.


25 February 2022

[1] https://committees.parliament.uk/call-for-evidence/640/?slug=critical-national-infrastructure-and-climate-adaptation

[2] https://smarter.energynetworks.org/

[3] National Grid ESO (2021) – Virtual Energy System: Power by National Grid ESO