Environmental performance

On this page, you can find out how we’re performing across a range of activities that impact on the environment. These include greenhouse gas emissions, treatment of resources, how we care for the natural environment, our approach to environmental management, and how we’re delivering responsible construction.

Environmental performance – delivering a sustainable network  

As the owner of the electricity transmission network in England and Wales, we’re at the heart of the energy revolution.

But as we evolve in our role to support the decarbonisation of energy as well as other sectors, we must also ensure we’re environmentally responsible in the way we operate our network.

Our aim is to design, build and manage our network and assets in the most sustainable, affordable way.

How we're performing

Below are a range of activities that we are working on to reduce our impact on the environment.

Greenhouse gas emissions

As an infrastructure business, our day-to-day activities create greenhouse gas emissions (GHG). 

We're aiming to reduce our greenhouse gas emissions by:

  • putting carbon and environmental considerations into our decision making
  • looking at innovative ways to operate our network
  • managing energy in our office buildings
  • introducing alternative fuel vehicles in our commercial fleet.
Greenhouse gas emissions (Scope 1.2 and 3) million tonnes of carbon dioxide equivalent 
Greenhouse gas emissions

Electricity Transmission's carbon footprint (including line losses) for 2017/18 were around 1.8 million tonnes of carbon dioxide equivalent (CO2e). This is a 29% reduction in carbon from 2012/13.


Breakdown of emissions 2017/18 
A graph showing breakdown of emissions

Our greenhouse gases emissions come from four main sources:

  • electricity transmission losses
  • insulating gases (e.g. sulphur hexafluoride)
  • electricity energy use and fuel used for transport.

The largest source of carbon emissions is transmission line losses.  Line losses are taken into account when we decide on the type of overhead line we invest in. However, there is a limited amount we can do to reduce losses because they are mostly driven by the distance over which electricity is transmitted.

As electricity generation continues to decarbonise, losses will contribute lower carbon emissions because the lost electricity will be of a lower carbon intensity. Therefore, it’s largely out of our control.


Greenhouse gas emissions (without losses) thousand tonnes of carbon dioxide equivalent 
Greenhouse gas emissions (without losses)

Our controllable carbon emissions derive from our building energy use, our transport energy use and the leakage of insulating gases. From 2012/13, there’s been a 15% reduction from our controllable emissions.

Sulphur Hexafluoride (SF6)

For emissions that are in our control, the biggest source is insulating gases. In 2017/18, emissions from SF6 were 220,000 tonnes of CO2, a 10% decrease from 2016/17.

We use the insulating gas SF6 in some of our high-voltage equipment because it is the most cost-effective insulating gas that is commercially available. Unfortunately, SF6 has a high global warming potential and, when it leaks, contributes to climate change.

We are actively looking for alternatives for SF6 with the lowest Global Warming Potential. In 2017, we trialled G3 into our network, which accounts to 2% global warming potential of SF6.

Sulphur Hexafluoride (thousand tonnes of carbon dioxide equivalent)
Sulphur Hexafluoride emissions
Treatment of waste

Our goal is to make the most of all materials we own and purchase.

To achieve this, we follow three principles:

  • minimising waste
  • using resources more efficiently
  • reusing and recycling materials.

During 2017/18, we generated some 7,400 tonnes of waste. These are resources that we have not been able to reuse or refurbish, and that we’ve therefore recycled, sent to energy recovery or disposed of.

The waste generated in 2017/18 includes:

  • the municipal waste created by our canteens in our offices and substations
  • waste oil we recover from assets, wood pallets, asbestos, mixed WEEE, metal, paper and cardboard
  • any emergency fly tipping and spills.

Waste generated and diverted from landfill (including reuse/recycling and energy from waste) in tonnes – 2017/2018

Water use

The majority of water used by Electricity Transmission is used for cooling electricity cables. This water is returned to source after use, so equates to zero consumption.

 We work closely with the Canal River Trust to ensure this is returned to the standard required. The rest of the water we use is consumed by our manned substations for drinking water, boiling kettles, etc.

Municipal water consumed and extracted water used for cooling (megalitres) 2017/18

Fluid filled cables

The majority of the fluid filled cables on our electricity network were installed during the 1970s. The technology of the industry has improved since then, so we no longer install new oil-filled cables. However, these cables have an asset life of around 60 years, so we still have more than 1,200km of cables in service. 

During their lifetime, regular inspection and testing is carried out to ensure insulation and joints are operating correctly.  Our-best practice approach to leak detection, location and repair and oil recovery is significantly reducing insulating fluid loss.  In 2017.18 we recovered 25% of the oil pumped. 

Fluid Filled Cables - Recovered and Non-Recovered (litres)

Caring for the natural environment

As well as doing what we can to tackle climate change, working to enhance our natural environment and support ecosystems is crucial. 

Our company-wide ‘Natural Grid’ programme works with local groups and partners to manage land in a way that improves the local environment and benefits communities.

We measure value through 'natural capital valuation approach', supported by stakeholder and community input to develop plans that drive environmental, community and business value.

Creating sustainability action plans for our land

As the owner of the electricity transmission network, we own a huge amount of land. This includes more than 300 substations and the non-operational land around them, so we have a significant opportunity to care for the natural environment.

It's important that we manage the land we own in ways that deliver the greatest value to us and our stakeholders. We’re creating ‘sustainability action plans’ for 30 important sites around England and Wales which include supporting a range of Environmental Education Centres. So far, in 2017/18, we have developed Sustainability Plans for 21 of these sites.

Sites with a sustainability action plan

Environmental management

Our aim is to be a leader in the development and operation of safe, reliable and sustainable energy systems to meet the needs of our customers, communities, and investors.

We’ve continued to implement an environmental management system certified to the International ISO 14001 standard.

All of Electricity Transmission's material operations are covered by the ISO 14001 Environmental Management System. Since 2017 we’ve been accredited to the ISO14001:2015 management standard. 

ISO 14001 (employee coverage %) 
Environmental management graph
Significant environmental incidents

We have internal measures that ensure a continued focus on environmental performance and minimising the impact we have on the environment. This year we revised the scope and definitions of environmental incidents to ensure we’re measuring incidents that are our own fault and under our control.  

In 2017/18, Electricity Transmission had two significant environmental incidents. One incident, comprising the failure of a fluid-filled cable, resulted in the loss of oil; and a third-party strike on a cable, also resulted in the loss of oil. Our targets are zero significant environmental incidents.

Significant environmental incidents (own fault) 
Environmental incidents (own fault) graph

Significant environmental incidents (third party fault) 
Environmental incidents (third party) graph
Responsible construction

Transitioning to a low carbon economy requires huge investment in infrastructure. As the transmission owner for England and Wales, we play a vital role in the connection of new generation.

The scale of construction is significant: from connecting new nuclear power plants such as Hinckley Point C, which will provide low-carbon electricity for around 6 million homes, to the creation of the second phase of the London Power Tunnels, a 32km electricity superhighway below the capital.

Measuring the carbon intensity of our construction

Since 2015, we've been measuring the carbon intensity of our construction design to ensure we’re doing this in the most sustainable way. Carbon intensity is the measure of the carbon emissions of a project compared to the cost of the project.

 In 2017/18, the carbon intensity of Electricity Transmission's construction design was reduced by 37%.  Our aim to reduce the carbon intensity of construction by 50% by 2050.

Reduction in carbon intensity from our construction design (%) 
Reduction in carbon intensity graph
Contribution to decarbonisation

Contribution to decarbonisation

Learn about how we’re supporting the decarbonisation of electricity through a variety of programmes.

Find out more

Low-carbon initiatives

Low-carbon initiatives

Discover how we’re developing new ways to manage and reduce the impact of our network, business activities and operations on the environment.

Find out more

Our environmental future

Our environmental future

Find out what we’re doing to combat climate change and how we’re working on decarbonising the energy system for the future.

Find out more