Faris Churcher explores how technological advances can leak-proof – and future-proof – the conversion process.
The Government's target for Britain’s network of gas pipes to be ready to deliver 20% hydrogen nationwide from 2023 has focused minds on the practical implications. A significant contribution to the energy transition agenda, certainly, but addressing specific integrity and safety issues also needs to be part of the mix.
Britain’s Hydrogen Blending Delivery Plan, published by the Energy Networks Association in January 2022, maps out how all five of the gas network companies will work towards the Government target. It also highlights the extent of the prize from an environmental and sustainability perspective: blending 20% hydrogen into the gas grid will reduce carbon emissions by up to six million tonnes every year – the equivalent of taking 2.5 million cars off the road.
However, the blending of hydrogen into supplies does pose distinctive risks because of its more volatile nature and smaller molecular structure. Leaks from pipelines and associated assets would represent a new kind of safety challenge around those areas of the network where they occur.
The ideal solution, of course, would be to introduce new fit-for-purpose infrastructure designed, ultimately, to host 100% decarbonised gas. That, however, is simply impractical and would entail eye-watering levels of investment.
So the focus is on converting the existing network – all 284,000km of it – as part of a strategy to realise a zero-carbon gas grid by 2050. A large number of studies, trials and projects are already underway, and there is a general sense of confidence around the industry that the technical challenges can be fully and properly addressed.
The results of large-scale pilot programmes that focus on the blending of up to 100% hydrogen at transmission pressures – including National Grid’s FutureGrid project in Northern England – are likely to add significant new impetus to the conversion process in the near future.
Tackling The Technicalities
Some of the technical issues now under close scrutiny relate to metallurgy: the nature of hydrogen molecules mean they can permeate into metal, in particular materials such as carbon steel. And when those molecules react with carbon elements and form methane within the pipe or casing material itself, they cause it to expand and crack, a process called embrittlement.
The challenges also relate to the sizing, and associated pressures, of networks. Much of the infrastructure has been designed and installed for the distribution of natural gas, but you need to burn much more hydrogen – up to three times more – to achieve the same results when it comes to heating a home or fuelling business operations.
And, of course, such large-scale networks feature vast numbers of joints that individually represent potential leak points and therefore require careful monitoring, management and maintenance.
Many of these issues coalesce around the various valves and regulators that are maintained by specialist technicians in stations and similar facilities around the country. Those stations are operated in line with robust safety protocols, given the obvious risks already posed by leaks.
The blending of hydrogen into supplies, however, introduces further food for thought, and that is why specialist areas of the supporting industries have been working to devise and introduce hydrogen-ready solutions that could help to expedite the conversion process and deliver on the 2023 deadline.
Converting Innovative Thinking To Progressive Solutions
It has certainly been a focus of attention, and investment, at Oxford Flow. The firm has taken those challenges into careful account, for example, in the development of its IM series pilot-controlled gas regulators. They are compact in nature, can be retrofitted to systems and are machined and manufactured from 316 stainless steel, which is acknowledged to be less susceptible to the embrittlement process.
Of equal significance, they do not feature large elastomeric diaphragms – which are used in many conventional solutions and which, research suggests, fare less well in trials of hydrogen transmission at various pressures.
Instead, the company has deployed profile fields of hard materials as part of a hydrogen-ready product that requires less maintenance attention and is already in use in live operations. To cite one example of its alternative proposition, it directly addresses the issues around energy density. Many network stations are sized to deal with a one-in-twenty winter – a sort of worst-case scenario – and in that context, it’s important to bear in mind that an eventual change to 100% hydrogen would effectively triple the flow to meet demand in such circumstances.
So network operators will require regulators that can cope with such flow increases. At the same time, we’re typically in situations where the system is perhaps only 5-10% open, and at the low end of flow capacity, many standard regulators can experience instability.
Oxford Flow has invested hundreds of thousands of simulation hours and completed a testing regime to demonstrate that its IM series regulators can operate with stability at anything from zero to 100% of operating capacity. That helps to future-proof the system because they protect from the implications of any scaling up of flow as the blend of hydrogen grows as a proportion of the overall flow and new demand – perhaps in the form of new residential developments or industrial operations downstream – potentially emerges.
The firm has now cumulatively reached the equivalent of 10 years’ service across the regulators already installed, with no failures or unplanned maintenance. The company regards this as an example of supply chain innovation that genuinely helps to deliver on the imperatives of its industry and, indeed of wider society.
In its interactions with clients, the firm’s team finds it interesting to show them the data generated by its regulators. It typically looks very similar to data they’ve seen before, and they ask, “what’s so special about it?” In truth, there’s nothing special about it, and nor should there be. The company wants operators to see the same quality of data they’ve always seen – data that provides assurance – albeit now being delivered by a new, more sustainable and reliable solution.
It’s not only about converting the system; it’s also about converting the industry mindset to new ways of doing things – with the future in mind.
Faris Churcher is principal applications engineer with Oxford Flow