Cleaner energy in the pipeline?

points to loop pipelines, ensuing compliance with all regulations, and making room for new plays.

New studies and testing will be required. Greater analysis based on feeds of fatigue crack growth data. More deliberate consideration regarding the fact that the current infrastructure is not designed and may not be suited to carry large amounts of hydrogen.

Our number one opportunity is to enrich the natural gas supply we have, a gradual shift away from traditional gas products into hydrogen-based gas products in homes and industries.

Initially this must occur by volume. It will take some time.

New momentum Regardless of the intended use of energy pipelines, including which products are being transported and their intended routes, an emphasis on safety and upholding one’s reputation in the industry is paramount for all oil and gas companies proclaiming to be leaders in the move toward cleaner energy.

Their sights are set on the mitigation of risks associated with climate change, future proofing their business models and taking leadership positions with environmental sustainability and profitable results among top concerns.

Many oil and gas companies are transitioning their operations to handle hydrogen enriched natural gas, pure hydrogen and other potential product variants and blends, and other new forms of energy that are beginning to emerge as viable for transportation, commercial use, homes, and other alternatives.

We are in a changing energy landscape with a lot of new momentum running parallel with some uncertainties about which direction everybody is going in from a legislative and geopolitical point-of-view. It is difficult to overstate the role of advanced pipeline solutions from a safety, public image and profitability perspective – both as part of the transition to a ‘net-zero’ emissions mentality and, for growth-oriented oil and gas companies, to retain a competitive edge.

From our experience at Emerson, staying on top of guidance and advice derived from global markets is key. It is anticipated that the role of simulation, as well as AI, machine-learning algorithms, and self-learning adaptive methods, will play a critical role in the future design of pipelines and resource optimisation across pipeline networks.

That includes risk modelling software and capabilities as they relate to pipes that will be used to transport and store CO2 or hydrogen. Of course, there is much analysis and work to be done on the operational side. Reliable simulation-based applications integrated into modern SCADA systems that are readily available today from Emerson will continue to enable pipeline operators to deal effectively with daily concerns, regardless of the products flowing in their pipelines.

Testing, alongside further pipeline safety design, evaluation of risks, and education and training, will be more important than ever to keep everyone safe and ensure continuity across all operating conditions – in the rush to capitalise on the low carbon energy transition.

Nigel Curson, Vice President Technical Excellence, Penspen, UK, talks navigating the pathways towards a national hydrogen network.

Rising oil and gas prices this year have added extra fuel to the calls for a global shift towards alternative and more sustainable sources of energy. The UK government’s Ten Point Plan sets out the approach government will take to support green jobs, and accelerate our path to net-zero by 2050 in the UK.1 While immediate pressures – such as the return to economic activity after more than two years of the pandemic, and the war in Ukraine – have diverted short-term attention back towards the security of fossil fuel supplies around the world, the longer-term forecast for oil and gas demand is downwards as the international commitment to the energy transition accelerates. As oil and gas decline, the question of what to do with the infrastructure supporting these industries is important. Some may be reaching the end of their lifetime and will be a target for replacement. However, other parts of the infrastructure remain in good condition with significant potential to repurpose them for new energy sources.

The benefits of hydrogen Hydrogen has emerged as a key player in the energy transition. The Hydrogen Council estimates the market for hydrogen and hydrogen technologies will reach revenues of more than US$2.5 trillion/yr, and create jobs for more than 30 million people globally by 2050.2 The UK government’s hydrogen strategy suggests up to 35% of the UK’s energy consumption could be hydrogen-based by 2050.3

While the construction of new pipelines, compressor stations and other infrastructure to satisfy different entry and supply points will be essential, much of the existing natural gas pipeline network will be repurposed for hydrogen.

Hydrogen blending with natural gas will be an important step towards net-zero, however, 100% hydrogen must be the end goal to meet the targets. Transitioning to 100% hydrogen with a substantial commitment to green hydrogen produced by renewable power will significantly change the required gas network architecture.

Repurposing natural gas transportation systems The UK’s existing network takes natural gas from five principal import terminals (Bacton, Easington, Milford Haven, Teesside, and St Fergus) and a small number of underground storage facilities.

Gas is delivered to 22 million homes and industrial users via a transmission and distribution including approximately 7600 km of transmission pipelines, 250 000 km of distribution pipelines, and around 200 000 km of smaller pipelines.

Critical network energy balancing of the gas system is delivered by a combination of LNG imports, pressure variation in the network (line pack), and underground storage across several sites.

With the acceleration of the energy transition, initially, this is likely to continue to be the case, but with hydrogen being blended with natural gas and introduced into the network close to the gas import locations and industry supplied with 100% hydrogen. The hydrogen will be produced by thermal decomposition of methane by steam methane reforming (SMR), auto thermal reforming (ART), or partial oxidation (POX) with carbon capture and storage (blue hydrogen).

Reusing as much of the existing onshore and offshore network as possible to deliver domestic supply, security of supply, energy storage, routes to and from storage, carbon capture and storage (CCS), and renewable imports using offshore wind will be important to optimise users’ costs.

Technical considerations for the network will include requirements for multiple new and different entry points; the import of hydrogen as a gas, as a super cooled liquid, via ammonia or Liquid Organic Hydrogen Carriers (LOHC) from a global market; the potential requirement for new temporary connections to facilitate the transition; a substantial upgrade of storage requirements to deliver network balancing to accommodate renewables variability; and potentially separate supply networks to accommodate bio-methane and the very pure form of hydrogen required for use in fuel cells.

There are several factors to be considered in the development of a future-proof, sustainable hydrogen network.

Conversion strategy A likely first step in any strategy is to tackle industrial emissions. Following this, a clear conversion strategy will be essential for the delivery of an effective hydrogen network. Decisions would have to be made on whether to start by linking industrial clusters and then towns and cities. However, the inference is that the process would be incremental with natural gas and hydrogen running alongside each other until a 100% hydrogen network could be developed. This approach would likely require the construction of a few separate hydrogen pipelines with the significant cost exposure that would entail.

Furthermore, the speed of transition from blue to green hydrogen and the parallel reinforcement of the (renewable) electric grid to support a green hydrogen network are matters for consideration.

Network compatibility One of the most important issues to consider is the compatibility of the existing network.

In systems using steel materials and components, the most important issue relating to hydrogen and pressure-containing equipment compatibility is embrittlement or material degradation.

Hydrogen embrittlement covers a wide range of degradation phenomena, and is caused by molecular hydrogen diffusing into the metallic matrix. This reduces material toughness, yield strength, and fatigue properties. Hard microstructures are particularly susceptible, including welds or heat-affected zones close to welds.

Combatting embrittlement can lead to a reduction in operational pressure in the pipeline and reduced capacity, a problem when also considering the relatively lower energy value of hydrogen on a volumetric basis (1/3 compared to natural gas).

Possible solutions for steel networks, which are in the very early stages of development, include the use of liners, coatings, or the addition of oxygen to the gas. Much research is still required. Other implications include having to reduce operating cycles because of the reduced fatigue life, and concerns regarding dents since strain hardening could be more susceptible to failure. Non-metallic, fibre-reinforced polymer pipelines produced in half-mile lengths could offer an alternative solution to steel.

High-density polyethylene (HDPE) pipelines make up most of the UK’s gas distribution pipelines, and hydrogen has been found to have little effect on HDPE properties.

The effect of fugitive and other types of GHG emissions The main sources of fugitive emissions or leaks are venting for operational issues or emissions through cast iron or older infrastructure. Venting and blowdown are critical for normal operations but create emissions. Furthermore, hydrogen’s much lower ignition energy compared to natural gas potentially increases risks. Blowdown normally refers to reducing the pressure of a whole section, not just the content of a vessel. For venting and blowdown, a different approach may be required for hydrogen systems.

In a repurposing scenario, for joints and seals, the European Industrial Gas Association (EIGA) and the Compressed Gas Association (CGA) have recommended replacing all flanged joints with welded connections to avoid leaks. Considering some infrastructure has thousands of connections, this could be challenging. However, some experimental results yet to be published indicate leakage might not be such a problem as first anticipated.

Critical component/product maturity Critical components are wide-ranging and include hydrogen compressors, electrolysers, valve flanges, and fittings.

Before an effective hydrogen network can be established, it is essential to be certain that the products and components used are capable of performing optimally. In some cases, this will require a significant degree of product development and maturity.

Compression is necessary for hydrogen to achieve the required energy density. Centrifugal compressors are the compressor of choice for pipeline applications due to their high throughput. However, it may not be possible to repurpose all-natural gas compressors for high percentage hydrogen use. This is because, due to the molecular weight difference of

hydrogen, centrifugal compressors must operate at top speeds 3.8 times those of natural gas, creating significant stress in the rotor. Also, avoiding hydrogen embrittlement requires more stages and intercooling to a higher degree than natural gas.

Alternatives include reciprocal piston compressors, ionic liquid piston compressors, electrochemical hydrogen compressors, and piston-metal diaphragm compressors. However, a hydrogen network will require the development of much larger compressors than are available today.

In the same way, there are challenges with electrolysers around maintenance, longevity, and potential deterioration of the catalysts. No doubt solvable in time, but much has still to be learned about the manufacture of electrolysers and compressors at scale before we can have confidence in the establishment of a widespread hydrogen network.

Uptake of conversion for industrial users Industrial users will only convert to hydrogen if they can be reassured that their supply is guaranteed and secure. If, for example, an industrial manufacturer has only a single steam methane reformer to rely on for hydrogen, the concern would be that any breakdown would impact the business. By contrast, the natural gas network has many inputs and is demonstrably extremely reliable.

Connecting the UK’s industrial clusters so they could support each other through a hydrogen network would be one way of creating security of supply, generating manufacturer confidence, and encouraging greater support for the hydrogen industry.

Societal risk and mitigations Hydrogen has a much wider range of flammability limits (mixed with air) and significantly lower ignition energy compared to natural gas. This impacts safety around installations and increases hazardous zones that require ATEX-certified electrical equipment. It also increases the ventilation requirements and will require changes in plant layouts, buildings, and equipment.

The risk is higher for pure hydrogen close to the pipeline, but this reduces faster compared to natural gas as the distance from the source increases. As a result, the ‘zero risk’ distance for pure hydrogen is shorter than it is for natural gas.

Meeting the challenge In making decisions about the repurposing of natural gas infrastructure for hydrogen, asset owners need to enlist the support of a partner with solid expertise and a full understanding of hydrogen-related projects.

This may include: ) The design and installation of hydrogen pipelines storage systems, and production systems.

) Assessment of compatibility, capacity, upgrading of equipment, and management of materials testing.

) The support and maintenance of hydrogen and blended hydrogen networks.

) Regulatory support. ) Technical specifications and material selection recommendations.

The transition work to develop a hydrogen network, and particularly repurposing infrastructure with uncertain provenance, is complex and requires detailed preparation and potentially expensive testing. For asset owners, a critical component of this work is a feasibility assessment and review of existing assets.

Uniper UK Ltd recently commissioned Penspen to carry out a fitness for continued service assessment, site audit, hydrogen feasibility technical report, and design and integrity review for the Theddlethorpe to Killingholme (KIPS) and Blyborough to Cottam (BCot) pipeline systems. The systems are designed to provide gas to Uniper’s owned and operated power plants at Killingholme, and the Cottam Development Centre (CDC) respectively.

Uniper is investigating blending hydrogen with natural gas at various ratios, up to 100% hydrogen, together with the suitability of the existing BCot and KIPS assets. The company requested a study to determine their feasibility and system compatibility with hydrogen.

The study incorporated all pipeline system elements, including the pipeline, inlet and outlet points, block valve stations (BVS), above-ground installations (AGI), pressure reduction stations (PRS), and off-takes.

The services included a site audit and assessments at various levels. These included a collation and review of documentation; an equipment inventory audit; system flow assurance and thermal input assessment; hydrogen degradation mechanisms; AGI equipment; pipeline design and integrity reviews; safety assessments, including venting and hazardous area zones; maintenance and inspection changes; a pipeline quantitative risk assessment (QRA); personnel competency and training; emergency response; and regulatory requirements.

The hydrogen feasibility technical report contained evaluations of the above-ground equipment and pipelines within the two systems. The company also received an extensive list of recommendations, to ensure the assets are safe and ‘hydrogen ready’ before transitioning, plus an implementation plan of the next steps.

The way ahead? The energy transition is underway, and hydrogen will have a key role in delivering sustainable energy to the UK. To support hydrogen’s growth, the repurposing of existing transportation systems will be critical. However, developing a hydrogen network must be done with caution, bearing in mind the longevity of the likely requirements.

Much research has been done, and much more must still be done, in this rapidly developing area.

References

1. www.gov.uk/government/publications/the-ten-point-plan-for-a-greenindustrial-revolution 2. hydrogencouncil.com/wp-content/uploads/2017/11/Hydrogen-scaling-upHydrogen-Council.pdf 3. assets.publishing.service.gov.uk/government/uploads/system/uploads/ attachment_data/file/1011283/UK-Hydrogen-Strategy_web.pdf