National Grid · Physical Exposure and Transition

SF6 (GWP 24,300) leaks from HV switchgear. Vendor readiness on SF6-free switchgear sets the phase-out timeline. Single largest Scope 1 lever available to a TSO.

SF6, used as an insulating gas in high-voltage switchgear, is National Grid's single largest Scope 1 source: fugitive emissions were 321 ktCO2e in FY20/21 and remained material at 278 ktCO2e in FY23, with a 22,800-24,300x GWP meaning even small leaks carry outsized carbon impact [E2][E3][E4]. Exposure runs across both transmission (SF6-insulated substations like Richborough and the IFA interconnector) and distribution networks (NGED's 145kV live tank circuit breakers), where legacy assets across the UK network still hold significant SF6 inventory, including ~28 tonnes identified in same-design assets beyond the initial pilot site [E4][E5].

National Grid targets a 50% reduction in SF6 emissions by 2030 (from 2019) and full elimination by 2050, backed by an IFA interconnector asset replacement programme expected to cut leakage 70% by 2025 and trials of non-SF6 vacuum circuit breakers in the US [E1][E2]. It has deployed a world-first SF6 retrofill with Hitachi Energy at Richborough substation (755kg replaced with low-GWP g3 gas, ~99% CO2e cut), is funding a £1.9m University of Manchester retrofill R&D project, and is piloting in-service leak sealing with Rawwater [E3][E4]. NGED separately runs a 20% SF6-loss reduction target for RIIO-ED2, with seven non-SF6 145kV circuit breakers already active and an eighth ready, developed jointly with Siemens, Schneider, Hitachi and Lucy via the ENA Notice of Conformity process [E5].

Steel, aluminium, copper, concrete for every new circuit + substation. Sector decarbonisation of these materials caps how quickly grid Scope 3 falls.

National Grid's build-out materials exposure sits in Scope 3 Categories 1-2 purchased goods and services, currently calculated on a spend basis at ~490,000 tCO2e for NGED in 2023/24 [E1]. Five procurement categories drive 70% of this footprint: underground cabling (30%), construction (15%), dig and lay (9%), transformers (9%) and tree trimming (8%) [E1][E3] — reflecting the steel, copper and concrete intensity of reinforcing and extending the distribution network. Network losses from the physical grid itself (~782,803 tCO2e) are a related but separate embodied-operational exposure that is expected to grow as electrification raises utilisation [E2].

National Grid is moving from spend-based to activity-based Scope 3 accounting for its top five procurement categories via a deep-dive project with consultants Anthesis, aiming for more accurate embodied-carbon attribution [E1][E3]. NGED is requesting EPDs/LCAs from transformer suppliers and building Project ALPACA, a PAS2080-aligned embodied carbon tool, to quantify and manage construction-related emissions [E1]. Note that business travel and contractor activities were removed from the Business Carbon Footprint scope under RIIO-ED2, narrowing reported Scope 3 categories to 1, 2, 5, 6 and 7 [E5]; a company-wide 37.5% absolute Scope 3 reduction target by 2033 from a 2018 baseline is in place per SBTi but no build-out-materials-specific target is disclosed.

Contractor + OEM supply chain (transformer, cable, civils) carries most enabled Scope 3 through embodied materials.

National Grid's Scope 3 Category 1 purchased goods and services — driven by underground cabling, transformers, dig-and-lay civils and tree trimming — accounts for roughly a fifth of Scope 3 emissions, with Cat 1+2 running at ~490,000 tCO2e in 2023/24 on spend-based factors, and the top five procurement categories alone covering 70% of that footprint [E6]. Embodied carbon in transformers, cable and construction materials from its top 250 suppliers is therefore a material lever alongside the far larger sold-energy Scope 3 categories [E1][E4].

National Grid runs a formal top-250-supplier engagement programme with a target for 75% to hold active carbon reduction targets by 2030, reaching 62% in FY23 (up from 49% in FY22) [E1][E4], and weights carbon at 10% of tender/design scoring decisions [E1]. It is a CDP Supplier Engagement Leader with high supplier response rates to its Climate Change Supply Chain requests [E1][E2][E4], works with the Carbon Trust to target the most carbon-intensive suppliers for SBT adoption [E4], and its NGED subsidiary is shifting from spend-based to activity-based emissions accounting via an Anthesis project, requesting EPDs/LCAs from transformer suppliers and building the PAS2080-aligned Project ALPACA embodied-carbon tool [E6]. Its SBTi-verified Scope 3 target now covers the entire value chain, with a 37.5% absolute reduction commitment by 2033/34 from a 2018 baseline [E5].