Executive Summary

Every year, European gas transmission system operators (TSOs) pump vast amounts of natural gas through their networks towards final use, typically to be burnt as a fuel to generate heat and power for industry and households. This releases huge volumes of carbon dioxide into the atmosphere — amounting to about 800 million tonnes, or 29% of the EU’s total fuel combustion emissions, in 2022. With their dedicated networks of pipelines, liquefied natural gas terminals and gas storage facilities, these regulated monopoly companies are responsible for the regasification, compression, transportation and storage of gas. 

The ongoing energy transition and accompanying move away from gas consumption have presented gas TSOs with an existential threat. Their regulated business model, which has traditionally attracted billions of euros in low-risk, long-term investment and financing each year, will no longer be viable as gas is gradually displaced from the energy mix. This could lead, at some point, to investor flight and a downward rerating of equity valuations in the sector.

Gas TSOs’ combined response has been to aggressively pivot and rebrand, collectively promoting the vision of a “multi-molecule” transmission grid by 2050 to European governments. In their vision, today’s polluting fossil methane will be replaced by a combination of lower-carbon gases, such as biomethane, green and low-carbon hydrogen, and captured carbon dioxide, meaning the transport of molecules for fuel and feedstock would still be needed and regulated (and TSOs’ business saved). 

For this to manifest, entirely new energy systems and value chains for hydrogen and carbon dioxide will need to be developed. Assuming the substantial techno-economic challenges can be overcome, TSOs aim to own and operate these new networks by constructing new pipelines and facilities, including repurposing some of their existing gas networks. TSOs have so far been very successful at gaining political support for their vision, avoiding (or at least delaying) discussions about a managed phasedown of their gas assets and thereby preserving their business model for a number of years. However, as their conceptual vision meets the realities of implementation (including stubborn physics, chemistry and energy economics), they are clearly making an ambitious bet. Progress towards their multi-molecule vision is already delayed, especially when it comes to green hydrogen and carbon capture technologies.

In IEEFA’s view, TSOs cannot credibly claim that they (and their vision) are part of the European energy transition story without fully disclosing annual emissions from the final use (combustion) of the gas they transport. These “transported emissions” are by far the largest emissions category in their value chain, orders of magnitude larger than their reported Scopes 1-3 emissions combined. But to date, TSOs have excluded them from Scope 3 reporting, citing the technicality that they do not own or sell the gas, only transport it. This clearly contradicts their marketed role as energy transition partners committed to reducing transported emissions by shifting to multi-molecule low-carbon gas networks. Global ratings agencies Moody’s and S&P have also noted this issue in their assessments of TSOs Snam’s and Gasunie’s sustainable finance frameworks, as has the think tank Anthropocene Fixed Income Institute. 

This loophole has formed thanks to a lack of clear guidance from standard-setter the Greenhouse Gas (GHG) Protocol, which currently sees three possible (and contradicting) interpretations of its Scope 3 standard in this context. One interpretation upholds the technicality of exclusion based on non-ownership or non-sale of gas. But the other two interpretations and the guidance of reputed data disclosure platform CDP all recommend reporting transported emissions given the clear materiality of this category. The Science Based Targets initiative (SBTi), a standard-setter for emissions reduction targets, had also encouraged TSOs to report these emissions before it withdrew its coverage of oil and gas companies and paused development of its oil and gas standard. Likewise, development of the European Sustainability Reporting Standards (ESRS) sector-specific guidance was put on hold to prioritise work on the EU’s new Omnibus simplification agenda. 

Thus, due to zero enforcement of CDP’s guidance, a lack of clarification from the GHG Protocol and the delay of relevant standards from ESRS and SBTi, there has so far been insufficient pressure on TSOs to improve their transparency. Instead, gas TSOs continue to report far smaller Scope 3 emissions, which focus on much less material categories such as upstream emissions from purchased goods and services, fuel and energy, emissions from associate/affiliate companies and even employee business travel. In some cases, TSOs have announced emission reduction targets for these categories. Separately, some TSOs also make claims around future “avoided emissions”, without reporting the emissions they are enabling today.

Ultimately, this reporting practice makes gas TSO businesses look far less polluting on paper to financial market participants. It could potentially lead to misallocations of capital, mispricing or underestimation of transition risk, and increased concentration of financial risk. Ongoing resistance to report these emissions demonstrates that TSOs’ leadership teams believe a higher emissions profile, even on Scope 3, might negatively impact their access to capital or cost of capital, and ultimately their shareholder value. This was referenced explicitly by industry association Gas Infrastructure Europe in a position paper published in August 2025 to defend the status quo: “Investors may be reluctant to fund projects of the system operators.” In IEEFA’s view, it should not be difficult for all gas TSOs to estimate and report their transported emissions as part of their Scope 3 reporting — rather it should be mandatory for a sector claiming to be integral to the energy transition. This reluctance of TSOs to acknowledge their existing role in gas-use emissions, albeit indirect, should give stakeholders cause for concern.

This report delves into a shortlist of six major European gas TSOs: Snam, NaTran, Enagás, Fluxys, Open Grid Europe (OGE) and Gasunie. It summarises their operations and strategies, and presents historical data on their reported Scope 1, 2, and 3 emissions alongside estimates of their transported emissions. The analysis quantifies and highlights the stark contrast between the emissions gas TSOs currently report and the full emissions impact of their value chain. The report also summarises the latest guidance and comments from disclosure platforms, standard-setters and ratings agencies on this topic. Some, such as CDP, SBTi and Moody’s, have explicitly highlighted this issue, while others such as the GHG Protocol remain noncommittal or silent on the topic. We urge the GHG Protocol (and others) to publicly clarify this point in their next Scope 3 guidance revisions, ideally in 2026. We also recommend that regulators and investors demand that TSOs quantify and disclose transported emissions within their Scope 3 reporting as soon as possible, to close this reporting loophole and deliver full transparency.

Key findings across six major European gas TSOs

• Transported emissions are on average about 150 times larger than total reported emissions.
• All the TSOs exclude these emissions from their Scope 3 reporting, ignoring guidance from CDP and SBTi that they should include them as Scope 3 category 11 emissions.
• Only two TSOs publish estimates of transported emissions (Snam and Gasunie).

Data from some TSOs for some years is incomplete or unavailable. In these cases, IEEFA has used estimates.