How SGN is reducing emissions and creating a zero-carbon gas grid

The figures show that by 2032 investment in replacing old iron mains gas mains pipes with new hydrogen-ready pipes will have reduced emissions from the country’s network of gas pipelines by the equivalent of the carbon emissions of 526,433 cars since 2014, through the Iron Mains Risk Replacement Programme.

SGN runs the local gas network in the South of England and in Scotland, and it plans to reduce leakage from its networks by the equivalent of 171,300 tonnes of CO2 in the GD2 period of 2021-26. GD2 is the next period in which gas network companies deliver investment that is approved by the energy regulator, Ofgem. Like all gas network companies it has submitted its GD2 plan to Ofgem, which is currently awaiting approval.

Throughout this case study, we use the phrase ‘ktCO₂e’ which stands for the equivalent thousands of (kilo) tonnes of carbon dioxide, the main greenhouse gas that we need to reduce to tackle climate change.

How does SGN identify and prioritise the right pipes for replacement?

In the last seven years, SGN has become the first gas network to use predictive data analytics to prioritise pipes for replacement based on leakage volumes. In the next price control it plans to extend its analysis to identify leakage ‘hotspots’ on gas services. It has also led the industry in the use of robotic technology to repair large cast iron main joints, completing repairs to approximately 15,000 joints using this technique since 2013.

Its GD2 plan details the additional reduced leakage opportunity through speeding up its delivery of the Iron Mains Risk Reduction Programme, and by increasing the rate at which it replaces steel pipes. If supported by Ofgem, these two approaches would save a further 2.2ktCO₂e each year (11.2ktCO₂e over GD2).  

By targeting its accelerated programme in areas that are more likely to be early converters to hydrogen, SGN would also facilitate the creation of a hydrogen-ready network sooner, which would enable more substantive reductions in carbon emissions in the future.

What is SGN doing to reduce damage to gas pipes from others?

SGN is targeting a 15 percent reduction in ‘third party’ damage to its network in GD2, which will contribute to its leakage reduction programme and reduce gas emissions to the atmosphere. Third party damage is damage to gas pipelines that is caused by other people or companies, such as construction companies digging in the ground.

Its education programme and digital tools are designed to improve awareness of where its pipes are located for people working on the land. 

It also provides a tailored self-service website, ‘LinesearchbeforeUdig,’ to provide instant online access to its mapping data. It has experienced a significant 43 percent drop in unplanned interruptions caused by third parties in the first year of use.  

It has also focused on education programmes for the agricultural community through its partnership with Scotland’s Rural Colleges network. And, it has also developed training about pipeline safety which is now being delivered across all six rural colleges, educating future landowners about pipe risk, and is being rolled out across other land-based courses in colleges across the UK.

What role is innovation playing?

New innovations such as stent bags or the high-volume gas escape toolkit will reduce emissions of methane into the air, but these benefits will not be picked up in modelled leakage figures. However, SGN estimate that these innovations could help to reduce leakage during a gas escape by 4.7ktCO₂e in GD2.

What’s a stent bag?

The stent bag is the remote insertion of a sealing stent system into the gas main at a distance from the gas escape. The stent bag is then pushed to the point of the leak and expanded to temporarily seal the leak while a repair is undertaken. SGN’s tests have demonstrated that by using more of these, leakage could be vastly reduced or stopped without disrupting the gas flow.

What’s a high-volume gas escapes toolbox?

High volume gas escapes carry considerable risk, so SGN has been exploring alternative methods to reduce the volume of released gas. It has developed sealing tools and plugs to physically stop the gas from escaping, along with an increase in monitoring sensors to aid rapid identification of escapes.

How can changing the pressure of gas in the pipelines help?

Reducing the gas pressure in the network can reduce the leakage. However, the gas pressure needs to be maintained at a sufficient level to meet customer demand. Active pressure management techniques enable SGN to profile gas demand patterns and optimise the right pressure in the pipes to meet customer demand and minimise leakage to the lowest possible levels.

During GD2, SGN plans to further refine its active pressure management regime and continue to reduce its leakage through smarter network control and remote management. It will pilot this active pressure management innovation in its southern network leading to an anticipated leakage reduction of 7.4ktCO₂e. At the same time, it is proactively discussing assured pressure levels with independent gas transporters to understand whether they can be reduced.

What does this all mean in terms of numbers?

Pro-active steel: - 7.6 ktCO₂e

Pressure managemrnt: -7.4ktCO₂e

Innovation (HGV/stent bag): -4.7ktCO₂e

Accelerated repex: -3.6ktCO₂e