This innovation project will allow Gas Network operators to introduce Hydrogen- Natural Gas mixtures and 100% hydrogen into existing networks with a minimum of network reinforcement costs without increased safety, integrity, or environmental risk.
The repurposing the gas network to be carry Hydrogen can be done using efficient and safe design practices to deliver a low carbon heating solution.
The project will produce the insights and findings needed to facilitate the decision making for re-purposing the existing gas network and thus provide a low carbon energy network.
In a move to decarbonise the gas networks, SGN are working on a number of hydrogen projects that offer a credible and opportunistic route to securing the asset for gas networks in the future of energy. This requires a wide collaboration with different project partners to deliver projects such as H100 Fife deliver a demonstration of a 100% hydrogen network. This SIF project aims to support this roadmap of reaching net zero targets.
SGN will partner with DNV to establish the necessary test campaigns needed to deliver valid results, using specialised materials laboratories in Loughborough and a full-scale major hazard research testing and training facility at Spadeadam, Cumbria. The Spadeadam site is already a key element with the H21and FutureGrid projects and these facilities are available for this project.
DNV Supplies and supports network simulation tools and has many years' experience developing bespoke digital solutions that allow UK Gas Network Operators to manage and operate their gas networks. Combined with DNVs gas network simulation software, DNV can test and validate the effects of predicted hydrogen gas velocities on existing and future network assets.
The outcome from the project may be simply deployed to network designers through the update of IGEM standards. IGEM may be invited to join the project and through them SGN and DNV will share the output from the work and will support the update of the relevant standards.
The potential users of innovation work are all GDNs and other designers of gas systems (IGTs / UIPs). All these bodies will be able to make use of the update of the IGEM standards and apply the limits determined within network analysis software for design.
Problem Bring Solved
For the design of pipes in a natural gas system a nominal maximum velocity is assumed as a good practice limitation. The IGEM standards (e.g. IGE/TD/3 or IGE/TD/13) refer to two velocity constraints:
- 20 m/s -- for networks where dust or debris is present.
- 40 m/s -- for networks where no debris is present.
These limits are historic practice and research, and it is uncertain if these limits are applicable to the current natural gas network, and it not known if these are necessary limits for a future blended or 100% hydrogen network.
The key driver for the lower limit is the presence of debris. Whilst it is not typical to experience dust in the network generally, historically the low and medium pressure gas networks have been known to contain "debris", from sources including the legacy of the manufacture towns gas. The limit of 20 m/s is intended to reduce the risk of pickup of debris which would cause internal erosion of pipes and fittings (bends, tees etc.), leading to the early failure of the pipe.
Hydrogen gas contains a lower level of energy per unit volume than natural gas. Consumers of 100% hydrogen would require an increased flow of over 3 times to deliver the same heat energy. This flow increase will result in a significant increase in the velocity of the gas in the system, likely exceeding the current limits, unless there is substantial investment to increase pipe size and/or pressure.
The properties of hydrogen differ from natural gas, so it is not known if maintaining the 20 or 40 m/s limits are necessary, and what limits are required. Other than debris erosion, high velocities may introduce other risks such as noise and vibration; this too needs to be established.
The Discovery project will:
- Conduct a literature search into the potential constraints to velocity (e.g. debris, noise, vibration)
- Document current GDN experience of debris.
- Justify, and define the scope and outputs, for the Alpha phase of the project to determine the gas velocity design limit(s) to be applied to 20% hydrogen blends and 100% hydrogen. This includes identifying the sources and definition of the "debris" to be used in tests.
- Determine the work required to investigate the impact any limit would impose on design outcomes, any potential mitigation measures and the basis for any further stage required to investigate the presence of debris within systems.
Impacts and benefits
Is the project still worth pursing and why is it cost effective to pursue?
The findings of the discovery phase, especially those related to the impact debris may have on erosion in hydrogen, indicate that a further project is essential to setting velocity limits which support the re-purposing of the gas network for hydrogen.
The project has confirmed that there are potential risks that setting an inappropriate velocity too high may bring risk to the asset, the safety of the system and to the environment. However, a velocity set too low may mean necessary capital investment to transition the network for hydrogen potentially increasing cost to the consumer.
How has the Project progressed towards the benefits outlined in the discovery application?
The Discovery Phase has made recommendations for:
- the potential for enhanced hydrogen uptake and erosion rates to be further investigated to determine the risk to network assets
- studies to be performed to revise the current erosion models and consequent velocity limits.
- the erosion models to be validated for hydrogen and hydrogen blends developing the required theoretical modelling to allow the definition of a full scale test programme and the design of the required facilities.
- investigation required to understand particle transportation and how this might affect erosion.
- validation of modelling for noise and vibration risk in hydrogen to establish whether they can be applied and to define what test work is required.
The project has identified some mitigating factors have been identified from other work being carried out by the gas industry. Primarily, this is the CFES data which indicates that dependent on the scenario demand levels which may be lower, meaning flow rates and thus velocities may be lower. Enhanced levels of mains replacement in the lower pressure tiers are also factor.
A detailed cost/benefit analyses should take these factors into account.
The Alpha Phase should also include a wider consultation with the industry which will seek to confirm NGGT and GDN experience of debris, applicability of the testing to be proposed and the approach to the cost / benefit analysis.
