Performance – environmental sustainability

Our environmental sustainability strategy, Our Contribution, focuses on the areas where we can make the greatest contribution to a more sustainable future.

With Our Contribution, we’re working to respond to global environmental and social challenges, minimise risk and continue to deliver the service our customers rely on.

We have identified three main themes that are most significant for our business and our stakeholders. These are:

We have set an additional target of a 70% reduction in GHG emissions by 2030 (against a 1990 baseline) to provide a clear milestone between our 2020 and 2050 targets.

Our targets now include the Greenhouse Gas emissions from electricity line losses, meaning all of our Scope 1 and 2 emissions are included in our targets. We have removed the emissions from our UK Gas Distribution from our reporting and targets, following the sale of our majority stake in this business.

We have updated the Global Warming Potential (GWP) figures we use to reflect the latest climate science.

All historical emissions data and our baseline has been amended to reflect these changes to ensure we are reporting emissions on a consistent basis.

Following these changes our revised 1990 baseline is 21.6m tonnes of CO2e.

Climate change

At National Grid we recognise and support the science that says our climate is changing due to the impact of human activities. We therefore measure the impact we have on the climate and have set ourselves goals to reduce our greenhouse gas emissions.

We independently assure our greenhouse gas emissions against the international standard ISO 14064-3 greenhouse gas assurance protocol.

We forecast that we will continue to significantly exceed (better) the 45% by 2020 reduction target. We expect the 2050 target (against our 1990 baseline) to be extremely challenging.

Scope 1 and 2 greenhouse gas emissions

Our Scope 1 and 2 greenhouse gas (GHG) emissions are reported in line with the WRI/WBCSD Greenhouse Gas Protocol Corporate Standard for all six Kyoto gases and using the operational control approach for emissions accounting.

Our targets now include the Greenhouse Gas emissions from electricity line losses, meaning all of our Scope 1 and 2 emissions are included in our targets. We have removed the emissions from our UK Gas Distribution from our reporting and targets, following the sale of our majority stake in this business.

These Scope 1 and 2 emissions are independently assured against the international standard ISO14064-3 Greenhouse Gas Assurance Protocol.

Our total Scope 1 and 2 emissions (including line losses) for 2017/18 were around 7.7 million tonnes of carbon dioxide equivalent (CO2e). This represents a 65% reduction on our 1990 base line. 

Breakdown of emissions 2017/18
A chart to show Breakdown of Emissions
Scope 3 greenhouse gas emissions

Our Scope 3 greenhouse gas emissions are reported in line with the WRI/WBCSD Greenhouse Gas Protocol Corporate Value Chain (Scope 3) Standard. We independently verify the emissions associated with our US sold product.

Our Scope 3 emissions for 2017/18 were 31.6 million tonnes carbon dioxide equivalent (2016/17: 34 million tonnes), and consisted of:

  • around 2.5 million tonnes associated with the procurement of goods and services
  • around 29 million tonnes associated with sold product (gas and electricity) in the US
  • other Scope 3 emissions of around 0.067 million tonnes, including business travel using third party carriers and employee commuting.

The majority of our Scope 3 emissions are entitled from two key business activities. The sale of gas and electricity to consumers in the US (91.8%) and the purchase of goods and services (8%). In comparison, business travel, employee commuting and waste account for 0.2%.

In the US, our reported emissions associated with customers may rise as our customer base increases. However, our energy efficiency programmes are making a real difference in helping our customers reduce their energy use. The American Council for an Energy-Efficient Economy (ACEEE) scored all three states that we operate in among the top seven for energy efficiency, with Massachusetts ranked at number one. 

National Grid is a founding member of the Natural Gas Supply Collaborative, a voluntary group of natural gas purchasers that promote safe and responsible deployment practices, and ONE Future, a coalition of natural gas utilities, and gas production, processing, transmission and distribution stakeholders that advocate for approaches that would lower methane emissions.  Further information can be found here.

In the UK the biggest contribution we can make to the environment is by connecting low-carbon and renewable energy to our network. We are also working hard to reduce our own carbon footprint. We have recently introduced a carbon calculator into our tender process. This is good news for the environment and for consumers because it reduces our impact on the environment and reduces our costs.

Scope 3 emissions customer use (bottom data) supply chain use (top data) (million tonnes CO2e)
A chart to show Scope 3 Emissions Customer Use
Scope 3 emissions other (million tonnes CO2e)
A chart to show Scope 3 Emissions other


Carbon intensity

We measure our carbon intensity. For 2017/18, including line losses, this was around 505 tonnes carbon dioxide equivalent per £ million of revenue compared with 424 tonnes in 2016/17 excluding line losses.

Carbon intensity (tonnes per £million)


Climate adaptation

As well as reducing our Scope 1, 2 and 3 emissions, it is equally important we understand the impact of past global emissions on future climate change.

We have developed climate change adaptation risk assessments for our regulated UK gas and electricity businesses. The assessment process used the government's latest available climate change scenarios to test the resilience of our networks to a range of future conditions. The feedback from the process showed that National Grid has a good understanding of the risks posed by potential future climate change and has a high degree of resilience already built into its networks. The ongoing monitoring and appropriate mitigation of the risks from a changing climate will be through our day-to-day business risk management processes.

In the US, we continue to work with state task forces and the primary focus of our adaptation work has been on flood-risk assessment and mitigation requirements for our electricity assets. This also includes work we are doing with US Department of Energy DOE and our participation in the Partnership for Energy Sector Climate Resilience; an initiative to enhance US energy security by improving the resilience of energy infrastructure to extreme weather and climate change impacts.

Sulphur hexafluoride 

Sulphur hexafluoride is an extremely effective electrical insulator and has significant advantages over alternative materials. It is non-flammable – a critical requirement in the high-voltage applications we use it – and because of its effectiveness takes up less volume than an equivalent insulating volume of an oil alternative.

Sulphur hexafluoride (SF6) is a greenhouse gas – one tonne is equivalent to approximately 22,800 tonnes of carbon dioxide.

Sulphur hexafluoride losses (tonnes) 


Sulphur hexafluoride inventory (tonnes) 


Energy use

Our energy use is dominated by gas and oil used by our US generation facilities.

Our generation facilities on Long Island used approximately 10.4 million MWh of natural gas and 0.65 million MWh of fuel oil during 2017/18. 

Our non-generation energy is used mainly by our gas-fuelled compressors on our UK gas transmission network and the Isle of Grain LNG import terminal.

In 2017/18 we used approximately 2.6 million MWh of gas and 0.5 million MWh of electricity in our non-generation activities.

Energy use: electricity (top data), gas (bottom data) (million MWh)
A chart to show Energy Use


Fuel used for transport 

During 2017/18, we used 39.1 million litres (2016/17: 49 million litres) of petrol and diesel for our commercial fleet, company cars and private cars used for business travel.

The reduction in 2017/18 is predominantly due to the sale of UK Gas Distribution. This meant our fleet inventory reduced by 7,000 vehicles. Previous years data has not been adjusted to reflect the sale of our Gas Distribution business.

Fuel used by transport (million litres)
A chart to show Fuel Used by Transport


Water use

The majority of water used by us is used for cooling at our generation facilities in the US and electricity cables in the UK. This water is returned to source after use, so equates to zero consumption.

Water consumed 

During 2017/18, we consumed approximately 1.54 million cubic metres (mcm) of fresh water for both operational and non-operational purposes across our operations; compared with 1.60 mcm in 2016/17. This equates to some 100.65 cubic metres per £ million of revenue (2016/17: 168.83 cubic metres per £ million of revenue).

Cooling water

During 2017/18, we extracted and returned to source around 1.104 mcm of sea water (2016/17: 1.266 mcm) used as cooling water at our US generation facilities.

Extracted water (top data) mains water (bottom data) (million cubic metres)
A chart to show Extracted Water and Mains Water
Water used for cooling (million cubic metres) 
A chart to show Water Used for Cooling


ISO 14001

We have continued to implement environmental management systems certified to the international standard ISO 14001. 

100% of our material operations are covered by ISO 14001 environmental management systems.

At 31 March 2018, approximately 93% of our employees worked to certified ISO 14001 environmental management systems; the same as last year. The remaining 7% are mainly office based employees in the US.

ISO 14001 employee coverage (%)
A chart to show Employee Coverage


Environmental incidents

In the UK we have had three significant environmental incidents, comprising: the failure of fluid-filled cable, which resulted in the loss of oil; a third-party strike on a cable, which also resulted in the loss of oil; and, failure in a substation gas zone, resulting in SF6 loss. Also, there are six ongoing SF6 leakages from electrical transmission equipment, where we are awaiting circuit outages to enable us to make the necessary repairs.

In the US, we have had one significant environmental release. A third-party contractor, not working for National Grid, was relaying a new water main for the Town of Whitman, striking a 2 inch, 60 PSIG PI main causing a gas release, followed by dust and foreign particle release. The incident was classified as a Category 1, due to the media attention and the need to temporarily move residents from their homes.

Our targets are zero significant environmental incidents.

Significant environmental incidents - own fault
A chart to show Significant Environmental Incidents - own fault
Significant environmental incidents - third party
A chart to show Significant Environmental Incidents - third party


Treatment of waste

During 2017/18, we generated some 0.111 million tonnes of waste; a considerable reduction when compared with 0.216 million tonnes the previous year. This equates to some 10.33 tonnes per £million of revenue. 

Of the 0.111 million tonnes of waste, around 96% was recycled; up 2% compared with the previous year.

A large, but variable, contributor to our total and recycled waste are the remediation of historically contaminated manufactured gas-plant sites and our construction activities. Depending on the level of construction and remediation activity, as well as the type of waste produced, there can be large year-to-year changes in our total waste and, to a lesser extent, the percentage of recycled waste. 

Please note the graphs below only show UK data.

Waste diverted from landfill (including reuse/recycling and energy from waste - UK data only) (%) 
Waste generated (million tonnes - UK data only)
NOx & SOx emissions

Our material emissions of NOx are from our generating facilities in the US and compressors installed on the gas transmission network in the UK. Our generating facilities in the US are our only material source of SOx.

In 2017/18, we emitted around 2,766 tonnes of NOx and 423 tonnes of SOx; compared with 2,306 and 2,102 tonnes respectively in 2016/17.

NOx emissions (tonnes)
SOx emissions (tonnes)
A chart to show SOx Emissions


Customer energy efficiency

In the US, our energy efficiency programmes are making a real difference in helping our customers reduce their energy use. The American Council for an Energy-Efficient Economy (ACEEE) scored all three states we operate in among the top seven for energy efficiency. 

Due to reporting requirements, our US energy efficiency data is on a calendar year basis and it is generally not available until October the year after. So the data here is for the year ending December 2017. 

We offer many electricity and natural gas energy-efficiency programmes for residential and business customers. For residential customers, the programmes offer various incentives and assistance to make homes more energy efficient; through lighting, appliances, high-efficiency heating equipment and water heaters, boiler controls, and insulating and sealing measures. For business customers, our electricity and natural gas energy efficiency programmes can help improve efficiency at existing or new facilities; by lowering operation and maintenance costs through efficient lighting and controls, heating systems, heating, ventilation and air conditioning (HVAC), windows and insulation instalments, and by participating in other industry-specific efficiency installations and programmes.

During the 2017 calendar year, participation in our gas energy-efficiency programmes had a 25% increase over 2016, with just 1.2 million participants. In 2017 there were just under 4.2 million participants in our electric energy-efficiency programmes, which is a 12% increase from 2016; combined, this resulted in 5.4 million participants in our gas and electric programmes.

Through participation in these programmes during 2017, customers saved over 32 million annual therms of gas and more than 1.2 million annual megawatt-hours of electricity. These equate to 188,279 tonnes and 525,945 tonnes carbon dioxide equivalent (CO2e) respectively, based on state-specific conversion factors. This is equivalent to the GHG emissions from 152,939 passenger vehicles driven for one year.

More information on our US energy efficiency programmes can be found via the energy service and regions links on our US website.

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