Under pressure: Digitising the gas grid

The UK’s gas network faces a significant problem with leakage, as the process of manually controlling pressure on the grid means it is often set too high. Utility Week explores plans to tackle this issue and pave the way for green gas to be injected into the system by finally digitising the gas grid.

The world has changed for gas distribution networks but to a large extent technology and working practices have not.

The journey of North Sea Gas entering the network at one end to be carried along a medium and then lower pressure system and ultimately dispersed into people’s homes is a 1970s solution coping with 21^st Century demand.

If the gas grid is to play a role in a net-zero UK it will have to be adapted to carry hydrogen and to allow biomethane to be injected into the system at multiple points.

Even before we get to that stage, the whole system already has an issue to tackle with leakage, with 2,300GWh disappearing from the grid every year.

A significant driver of this has been the challenge of maintaining the right network pressure to ensure the supply is always more than a match for demand. This can only be done by adjusting the country’s 26,000 governor stations – and as it stands this is largely a manual process.

The current, clearly unsatisfactory, position is for the pressure to be set for the worst-case scenario, ie the coldest winter morning of the year. The cost for gas networks and for the environment is clear.

To this end, work is underway to digitise the grid and find new, or improve on existing, methods of automatic pressure control solutions that can react to demand in realtime.

‘An opportunity to do things differently’

SGN is already trialling a way of operating governors in the Romsey area of Southampton remotely as part of an ongoing innovation project.

The company is using Utonomy’s prototype Active Grid Management system, which consists of controllers retrofitted to existing governors and loggers in the network which communicate with centralised software. The controllers continuously adjust the governor set points to maintain optimum pressure levels across the network.

SGN’s head of innovation, John Richardson, tells Utility Week: “There was obviously an opportunity to do things differently but when you’re looking to make any sort of changes to how the gas network operates, safety has to be paramount, so we knew we would need to do a lot of testing.”

The Phase 1 field trial, in early 2019, saw the installation of the first system prototype at five district governors selected by SGN. This initial field trial stage completed at the end of November 2019 and the second stage will now look to appraise the latest prototype design and includes another field trial stage. This work is funded through SGNs Network Innovation Allowance, provided by Ofgem.

It is proposed that the next stage will expand the test ground to south London and Edinburgh. Wales & West Utilities is also joining for this section of the trial, which will run until the Spring.

Utonomy founder and chief executive Adam Kingdon tells Utility Week there is widespread interest from other networks and that the solution fits in with Ofgem’s incentives for the next price control.

“Ofgem has put considerable weight on reducing average system pressures which effect emissions, so the draft determination includes penalties for increasing average system pressures above the level in the last year of GD1 and rewarded for dropping below that level. As average pressures have a tendency to rise following mains replacement through insertion more advanced solutions are clearly needed.”

Untapped potential in biomethane

In a separate trial with Northern Gas Networks (NGN), Utonomy is looking at how a new approach to feed-in management can be used to allow biomethane to enter the gas grid.

Kingdon explains: “A bit like renewable electricity, biomethane plants have to connect into the network a bit lower down the pressure tiers so they’re actually connecting into the medium pressure part of the network. In the summer or at night there may not be enough demand to get the biomethane in. So, what happens at the moment is that the biomethane plants have to flare, which is a huge waste and it’s very expensive for the plants. It takes about five days for them to change their output.

“We’re able to use our control system and AI to control the pressure on the network and readjust it so the biomethane feed is always prioritised over the natural gas feed.”

This trial begins next month based on the Gravel Pit biomethane plant in York.

Kingdon says that going forward the same technology could also be used for hydrogen.

Paul Massara, the former Npower chief executive, joined the Utonomy board as chair this summer and tells Utility Week he is excited about the potential in a too-often ignored area of innovation.

“If you look at the electricity side there is a lot of distributed electricity coming into the grid so that has led to the use of AI, digital twins, digitisation in general and flexibility. All of this applies to gas as well. How do you get biomethane in, how do you control pressure, how do you get data and how do you use AI to reduce carbon?”

However, he insists that clear signals are needed from the government for future investment in this area.

“There has been a lot of progress made on decarbonisation of power, there’s a pretty well-established road map for the decarbonisation of transport but we’re still be kicking the can down the road in gas. We need to invest now in the technologies to allow us to green the gas grid.”

Massara also points to the potential for the UK to be a world leader in digitising the gas network.

“This is a global issue given the interest in hydrogen and I think in many ways we are at the forefront. We are talking to other countries who just don’t have a solution for this.”