Performance – environmental sustainability

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

Our Contribution addresses global environmental challenges, seeks to minimise and continues to deliver the service our customers rely on.

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

Our climate commitment focuses on reducing the emissions from our operations and activities and we have set ourselves challenging long term targets.

We independently assure our greenhouse gas emissions against the international standard ISO 14064-3 greenhouse gas assurance protocol. The verification of our 2018/19 GHG emissions can be found here.

We also have a hugely important role to play in supporting the transition to a low carbon future and the GB energy system is set to achieve a historic milestone in 2019.

Climate Change

We know that by working together and sharing resources, National Grid can help deliver a cleaner, greener Britain. We are also focused on reducing our own carbon footprint.

We consider climate change risks and opportunities in terms of physical and transition risks. Reports concerning our UK operations under the 2008 Climate Change Act were released in 2010, again in 2016 and will be updated in 2021.  National Grid has also committed to implementing the recommendations of Financial Stability Board Task Force on Climate-related Financial Disclosures (TCFD) in full and our disclosure is available in our Annual Report.

In the short term, physical risks are most relevant, and we are principally focused on the risks from weather-related events in the US, and flooding events (in both the UK and US). We will actively update our understanding of potential risks by drawing on the UK Climate Projections 18, and are investigating other potential risks such as the impact of rising temperatures and widening temperature ranges on the performance and operation of the equipment on our networks. The ongoing monitoring and appropriate mitigation of the risks from a changing climate is part of day-to-day business risk management processes.

Scope 1 and 2 greenhouse gas emissions

We have an ambitious target to reduce our greenhouse gas (GHG) emissions by 80% by 2050 from our 1990 baseline of 21.6m tonnes of CO2e, with interim targets of 45% by 2020 and 70% by 2030. We have made good progress so far and are already exceeding our 2020 target.

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

We have made changes to the emissions factors used to calculate GHG leakage from our US gas distribution network, aligning our approach with current best practice.  Historical data presented here has been recalculated to reflect this change.

Our total Scope 1 and 2 emissions (including line losses) for 2018/19 were around 7.0 million tonnes of carbon dioxide equivalent (CO2e). This represents a 68% reduction on our 1990 baseline.

Greenhouse gas emissions (Scope 1 and 2 million tonnes of carbon dioxide equivalent)
Breakdown of emissions 2018/19
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 all our scope 3 emissions.

Our Scope 3 emissions for 2018/19 were 32.3 million tonnes carbon dioxide equivalent (2017/18: 31.9 million tonnes), and consisted of:

  • around 5.0 million tonnes associated with the procurement of goods and services
  • around 27.3 million tonnes associated with sold product (gas and electricity)
  • other Scope 3 emissions of around 0.0315 million tonnes, including business travel using third party carriers, employee commuting and waste.

Significant changes to our procurement of goods and services and other Scope 3 emissions can be attributed to modifications in the emissions factor used.  Our historic data has not been re-baselined to reflect this.

Most of our Scope 3 emissions are emitted from two key business activities.  The sale of Gas and Electricity to customers in the US (84.5%) and the purchase of goods and services (15.4%).  Business travel, employee commuting and waste in comparison account for 0.1%.

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 six for energy efficiency, with Massachusetts ranked at number one.

Scope 3 emissions customer use (bottom data) supply chain use (top data) (million tonnes CO2e)
Scope 3 emissions other (million tonnes CO2e)


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) 




Energy use

Our energy use is primarily gas and oil consumption in our US generation facilities.

Our generation facilities on Long Island used approximately 13.9 million MWh of natural gas and 1.5 million MWh of fuel oil during 2018/19.

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 2018/19 we used approximately 1.7 million MWh of gas and 0.6 million MWh of electricity in our non-generation activities.


Fuel used for transport 

During 2018/19, we used 35.5 million litres (2017/18: 39.1 million litres) of petrol and diesel for our commercial fleet.

The reduction seen 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 have not been adjusted to reflect the sale of our Gas Distribution business.


Fuel used by transport (million litres)


Water use

Most of the water we use is 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. Our water data is reported on a calendar year basis.

Water consumed 

During 2018, we consumed approximately 1.74 million cubic metres (mcm) of fresh water for both operational and non-operational purposes across our operations, compared with 1.65 mcm in 2017. This equates to some 116.52 cubic metres per £ million of revenue (2017/18: 110.49 cubic metres per £ million of revenue).

Cooling water

During 2018, we extracted and returned to source around 1,315 mcm of sea water (2017: 1,104 mcm) used as cooling water at our US generation facilities. We also extracted and returned to source 2.70 mcm of surface water at our UK operational sites.

Extracted water (top data) mains water (bottom data) (million cubic metres)
Water used for cooling (million cubic metres) 
ISO 14001

We have 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 2019, approximately 98% of our employees worked to certified ISO 14001 environmental management systems; the same as last year. The remaining 2% are mainly office based employees in the US.

ISO 14001 employee coverage (%)
Environmental incidents

We record any environmental incidents we have using an internal categorisation. Category 1 incidents are those we deem as significant - we use this approach to ensure we are consistently delivering high levels of environmental management, embedding the right behaviours in our business and striving for continuous improvement in environmental performance.

In 2018/19 we had six incidents we classified as Category 1, 5 in the UK and 1 in the US.

Significant environmental incidents - own fault
Significant environmental incidents - third party
Treatment of waste

During 2018/19, the UK business generated some 0.262 million tonnes of waste; compared with 0.111 million tonnes the previous year. This equates to some 51.9 tonnes per £million of UK revenue. This increase is the result of large volumes of excavated material as part of construction activities to deliver network improvements.

Of the 0.262 million tonnes of waste, around 90% was recycled.

A large, but variable, contributor to our total and waste diverted from landfill is our construction, demolition and remediation 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 waste diverted from landfill. 

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 2018/19, we emitted around 2,565 tonnes of NOx and 1,602 tonnes of SOx, compared with 2,766 and 423 tonnes respectively in 2017/18.

NOx emissions (tonnes)
SOx emissions (tonnes)
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 six 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 2018.

National Grid offers 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 2018 calendar year, participation in National Grid’s gas energy efficiency programmes had a 44% increase over 2017 with 1.8 million participants.  In 2018, there were 3.9 million participants in the Company’s electric energy efficiency programmes, which was a 7% decrease from 2017.  Combined, this resulted in 5.7 million participants in the gas and electric programmes.

Through participation in these programmes, during 2018 customers saved over 40 million annual therms of gas and 1.3 million annual megawatt-hours of electricity.  These equate to 236,670 tonnes and 546,263 tonnes CO2e respectively based on state-specific conversion factors.

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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