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As the gas sector mulls its future, alternative approaches abound
It’s not just biomethane and hydrogen that could be the gas grid’s saviours. Experts are also considering the benefits of transporting water or liquid ammonia on the network.
As the gas sector mulls its future, alternative approaches abound
It’s not just biomethane and hydrogen that could be the gas grid’s saviours. Experts are also considering the benefits of transporting water or liquid ammonia on the network.
The gas network is a behemoth, comprising some 280,000km of transmission and distribution pipelines criss-crossing the country, with supporting infrastructure such as compressor stations, valves, and governors.
Right now, the future of this system, which has powered the electricity grid, fuelled industry, and heated our homes for decades, is unclear.
Length of the UK's gas transmission and distribution networks in total
If net zero is a challenge, the gas industry has responded by outlining numerous potential ways of ensuring it has a future. July’s IGEM Policy Conference provided a flavour of the range of scenarios, from the contribution of flexibility, hydrogen and biomethane, to powering data centres using gas and encouraging greater uptake of hybrid heat pumps.
Amount of unabated gas-fired reserve envisaged under Clean Power 2030
For its part, the government has confirmed it sees a relatively small but vital role for gas for many years to come. The Department for Energy Security and Net Zero (DESNZ) said last summer that gas will “remain important for electricity security”. This includes, for example, maintaining 35GW of unabated gas-fired reserve generation capacity as part of Clean Power 2030.
James Earl, chief executive at Future Energy Networks, also sees the sector as supporting clean power. He told the recent IGEM conference that combining electricity with low-carbon gases, flexible generation and heat recovery could support economic growth while contributing to the Clean Power 2030 target. "If we don't pursue this now, we'll miss the opportunity of this generation," Earl says.13
Darren Elsom, chief operating officer at SGN, bullishly told the same event that gas remains "one of the most important industries in our country". Echoing the government’s strategy, he argues flexibility will see gas networks continuing to play a vital part in maintaining resilience, particularly during periods of peak demand.
Claire Dykta, director of strategy and policy at NESO, also says gas is central to providing flexibility and resilience as renewable generation expands, with dispatchable capacity, biomethane and hydrogen all playing roles.
However, Dykta stresses the value of gas will increasingly depend on its interaction with the electricity system and emerging technologies, supported by market signals, investment and policy. "We will only get this right together,” she says. Her colleague Jeremy Brutus, NESO head of hydrogen and gas policy, argues gas will remain integral to future energy scenarios only alongside growing deployment of biomethane and hydrogen.
There are still big question marks over the future of the latter. Tommy Isaac, director, energy and natural resources at KPMG, assessed the hydrogen policy landscape and began his presentation at the IGEM event with a blank slide to illustrate a lack of recent policy developments. Indeed, Isaac describes the sector as being in a period of "policy stasis". He also believes hydrogen's future is likely to shift from industrial decarbonisation towards flexible power.
Dr Angela Needle, director of strategy at Cadent, says we have the ingredients for a successful hydrogen economy, but, backing up Isacc’s point, warns that progress had stalled. She says schemes such as the HyNet project are vital for decarbonising industrial clusters where electrification is not viable, helping to protect jobs, strengthen competitiveness, and enable long-term energy security. (With this in mind, Needle adds that the sector is “very” concerned that DESNZ will be required to find a further £2 billion of savings as part of the new Defence Investment Plan.)
Inevitably, biomethane was also on the agenda at the IGEM conference. Tom Carlucci-Davies, senior manager at Baringa, says expanding biomethane deployment could reduce the cost of the energy transition by offering a cost-effective route to emissions reduction and greater system flexibility.
Carlucci-Davies says wider deployment of biomethane, particularly alongside carbon capture, could deliver significant savings while reducing the need for more expensive decarbonisation measures elsewhere in the economy.
Dr Hossein Ameli of Imperial College London argues biomethane should not be viewed simply as a low-carbon gas substitute, but as part of a wider interaction between biomass, hydrogen, electricity and gas networks. Ameli’s modelling explores how biomethane, hydrogen and natural gas could co-exist in a 2050 net-zero energy system.
All of which suggests, as the government gears up to launch a call for evidence on transitioning the gas system in 2026, that there is certainly no lack of options for securing the gas network’s future,
Meanwhile, other technologies are emerging that could have an impact, too.
Ice cool ideas for heat
Directions for gas such as biomethane or the development of the hydrogen economy, however much they may have stuttered, are well-established. But there are newer pathways that have come to light only recently.
One of these is the use of the gas network to transport water to heat homes, where ice heat pumps (also known as ‘latent heat pumps’) would be used to extract energy.
This concept was developed by Nottingham University professor of dynamics Seamus Garvey as part of a £1.2 million Engineering and Physical Science Research Council project looking at alternative ways of using gas distribution. (Garvey’s idea builds on research into ice heat pumps by Ziping Feng from the Chinese Academy of Sciences in Guangzhou, China.)
Latent heat pumps work by turning water into an ice slurry and extracting the energy released from the phase-change process when water transforms into ice for heating. This change combines a massive amount of thermal energy with a stable, constant temperature near freezing, allowing the heat pump to maintain a high coefficient of performance (COP) during cold weather.
For this reason, Garvey says latent heat pumps boast superior performance when it’s cold to the air source heat pumps typically being installed in the UK.
In the winter, air source heat pumps try to suck heat out of a source that is already cold and pump it up to a higher temperature. “Your COP is actually going in the wrong direction,” explains Garvey. For example, an ice-source heat pump typically achieves a COP ranging from 3.5 to 4.8, meaning it delivers 3.5 to 4.8 units of heat for every unit of electricity consumed. By comparison, an air source heat pump usually achieves a COP between 2.5 and 4.0 under normal conditions, with performance dropping further in freezing conditions. A latent heat pump maintains a COP above four even in very cold temperatures.
So, what are the drawbacks? While latent heat pumps are a proven (albeit niche) concept, the major hurdle from a UK perspective is sourcing the necessary water. Enter the gas distribution network, which could be used to transport the water needed directly into people’s homes.
Less water is needed than might be expected, Garvey explains. “If a house was going to use up 100kWh of heat in a day, which you might do in a medium-sized house, how much water would you have to freeze and throw down the drain? Less than a tonne.
“A tonne of water sounds like quite a lot, but in the middle of winter a tonne of water is absolutely nothing. The average household is throwing away almost a tonne of water every day.”
As for repurposing gas pipes for water, the team’s analysis indicates that the transition is feasible. There are no substantial concerns about the materials used for gas pipelines, which include polyethylene and steel, and which are also used in water transmission systems. Given the operating pressure in gas systems ranges from 13 to 21 bar, surpassing water transmission pressure, pressure would also not be a problem. Ice created during the process would be expected to melt in the sewer system.
The team has looked at all the angles, then, but has an industry to convince. Garvey has therefore taken pains to involve water and industry stakeholders from the beginning. “They remain very interested in this as a proposition,” he claims.
A proportion of the water needed could be sourced from rainwater, he says, which would be collected and stored in local depositories rather than on individual houses. High-pressure compressors and pressure reduction stations on the gas network would be converted to pumping and pressure-boosting units to achieve the necessary conditions to transfer water.
Could ammonia be a winter warmer?
Water is not the only substance the Nottingham University team has been considering carrying on the gas network. It’s also been looking at the potential of distributing liquid ammonia to heat our homes.
Ammonia has benefits including a much higher energy density than natural gas – around 350 times greater. Although ammonia can be toxic and highly corrosive, when it is mixed with water to make a solution called aqua ammonia, these effects are minimised, but the potential to supply energy remains.
Seamus Garvey’s team believes that ammonia would be cheaper than hydrogen to use as a domestic fuel, more cost effective to transport, and easier to store. Once in the home, a boiler unit would separate the ammonia from the water, burn the ammonia in the same way as natural gas, leaving behind carrier water safe enough to flush down the drain.
Finding an efficient way to separate the ammonia is key to the success of the concept. The project team says it has been able to achieve 97% efficiency in the separation process using its demonstrator, although it has not built a full-scale aqua ammonia boiler yet.
The next stage is to do just that as part of a scheme called Winter Ammonia, which is due to complete in 2029 and funded through the UK Research and Innovation Council. As well as developing an aqua-ammonia boiler, the project will look at where to source the fuel.
“Some ammonia could be produced here in the UK. We know we are going to have large amounts of wind power, and we need to use it for something. People are talking about using it to power electrolysers to make hydrogen, but some of that hydrogen could be converted to ammonia,” points out Garvey.
However, the potential benefits of a technology such as ammonia boilers are set against a backdrop in which the economy is increasingly electrified, which means many more air source heat pumps coming online in the coming years.
With that comes the thorny issue of how to decommission the gas network safely and effectively even as the industry works to prolong its use.
Disconnecting supply: Innovation’s role in decommissioning
As novel fuels are developed, another group of experts is considering how to ease the gas industry through the transition by improving the way customers are disconnected when they have adopted alternative space heating solutions.
Individual consumers are already disconnecting from gas when they install a heat pump, but there are concerns that the process for doing so is confusing and complex. “Today’s numbers [of disconnections] are small – around 20,000 in 2024 – but for consumers the process is a mess,” says Sustainability First associate Maxine Frerk.
“It’s confusing and complex with responsibility split across different parties, and with the costs varying hugely depending on the route you take and where you live. Even savvy energy sector colleagues have found it a headache.”
Last year, Ofgem issued a call for input and subsequently held workshops focused on what a framework for gas disconnections might look like. Frerk is concerned that this initiative may not see the light of day, however. “If heat-electrification is to seriously scale, the obstacles to gas disconnection need sorting,” she says.
So what does the disconnection process look like now? When a customer wants to disconnect from the gas network, the first step is for the supplier to remove the meter and cap the supply. The gas distribution network must then take action to ensure the remaining pipework is safe.
For this second step, there are currently two routes. The first is a ‘voluntary’ route in which the customer contacts the gas distribution network, the network arranges a time to do the work, and the customer is charged (the fee can be as high as £2,000).
The second (free of charge) ‘safety’ route is where the GDN is notified via the supplier, and after 12 months visits and carries out the job. In the latter case, the costs are socialised across all customers, so there is no charge for the property owner that is disconnecting.
This is a good choice – if the customer is aware of the options. But Frerk says that of the networks, only one (Wales and West Utilities) explains the process on its website, noting that the voluntary route should be used if you are doing building work and need the job done in specific timescales. The other three GDNs simply invite you to apply for a paid-for disconnection, Frerk says.
She would like to see customers signposted to the free route. But as disconnection volumes increase, it will become unfair to expect the declining pool of gas customers to pay via socialisation, which could have a disproportionate effect on vulnerable households, Frerk says. “Ultimately this question will be for DESNZ to address as part of its wider work programme on the future of gas networks and affordability, including looking at more radical options like funding through taxation or electricity bills.”
It’s clear, then, that innovation will be key to ensuring the gas network is used (and decommissioned) to maximum effect as the economy decarbonises. Just as the gas industry mulls alternative fuels or even water being transported on the gas network, disconnection strategy may require new approaches, too, with current innovation projects including back-filling pipes with foam and a ‘squeeze off’ tool to cut off supply of PE pipes at the mains.
Ultimately, with so many different strategies and technologies out there, the problem seems to be less one of finding good ways to use the grid in the future – but more a question of putting together a viable plan and sticking to it.
