Following our Integrated Energy Research Assistant, Jemma Reynolds', insightful presentation at Subsea Expo 2023 on mapping pipeline bundles for their repurposing used for hydrogen storage, we’ve taken a closer look at this project and explored the importance of hydrogen, why pipeline bundles are needed and how we are working with project partner, Cygnas Solutions.
The Importance of Green Hydrogen
Green hydrogen is a clean energy source that does not produce any greenhouse gases when utilised and can be relatively simple to form through the process of electrolysis. It is an extremely flexible fuel as it can be used across a plethora of industries, including automotive, aerospace and is now even being used to decarbonise residential and commercial heating systems. With its high energy density, it can be stored and transported via pipelines.
The NSC Integrated Energy team recognises that green hydrogen is essential to meeting the goals set out in the Paris Agreement and Net Zero targets that are currently in place, therefore a high proportion of the research carried out by the team is greatly focused on green hydrogen.
Challenges for Hydrogen Storage
Despite having an abundance of benefits, hydrogen still comes with its challenges, and these should always be considered when storing hydrogen in underground structures due to its increased permeability to porous media. Hydrogen embrittlement is always a potential issue when it comes to storing hydrogen and refers to the loss of ductility and strength due to the entry of atomic hydrogen into the metal lattice. This penetration causes brittle fractures that are always intergranular. Certain metals are more susceptible to embrittlement than others, consequently, making the risk of degradation and bursting very high.
Due to the higher pressure of hydrogen storage cylinders, the safety risk becomes greater, particularly in densely populated areas. Higher pressure makes the cylinders more susceptible to leaks and the ranges of flammability widen with the use of hydrogen over natural gas. This is particularly dangerous due to hydrogen gas being odourless and being fully reliant on sensors to detect any leaks
The Role of Pipeline Bundles
Pipeline bundles consist of a carrier pipe containing individual pipelines and umbilical components which are carried by spacers on rollers and terminated in towheads. Within the towheads, controls, cooling spools, HIPPS, valves and some subsea processing can be found. Pipeline bundles are fabricated onshore in a single length (7.6km) and are installed using a controlled depth tow method. To date, over 75 pipeline bundles have been installed in the North and Norwegian sea regions, with the majority installed from Wick, Scotland.
Pipeline bundles provide an economically attractive solution for high pressure, high temperature field development by incorporating advanced design and fabrication techniques. They incorporate all the structures, valve work, pipeline and control systems necessary to operate a field in one single product, delivering considerable value and potential cost savings for a wide range of applications, including high pressure and high temperature field developments. Bundles reduce pipeline corridor width to a minimum, avoiding unnecessary congestion, which can be an issue when installing multiple pipelines separately. Carrier pipes provide a corrosion free environment, reducing the need for individual corrosion coating of flowlines, again reducing overall site construction costs.
Why Bundles for Hydrogen Storage?
Pipeline bundles are within close proximity to many offshore wind turbines and can act as reserves for hydrogen to be used to bridge the gap between wind farm energy production rates and energy usage.
By design, bundles are low stress and have a high tolerance to fatigue. Their design can also provide significant advantages for hydrogen storage, such as high thermal performance with efficient insulation systems, and the carrier pipe provides a second barrier of protection. Utilising bundles for hydrogen storage can provide a sustainable decommissioning option which has the additional benefit to be potentially to be profitable. Previous life extension studies have shown minimal damage to bundles in service, meaning that they are being decommissioned in good conditions, allowing for easier bundle repurposing.
Project Partner – Cygnas Solutions
For this project, the Integrated Energy team have partnered with Aberdeen-headquartered Cygnas Solutions, provider of innovative engineering solutions in Mechanical Design, Simulation, Asset Integrity and Engineering Software Sales.
Cygnas Solutions have extensive experience across a range of industries, working with consultants, contractors and manufacturers to solve current and future engineering challenges faced by companies locally and globally.
About the Project
The project was developed taking into consideration the current insights:
- The need for hydrogen storage and developments of the H2 economy
- Pipeline bundles coming up for decommissioning
- Surplus energy being produced from wind turbines
The project was designed to assess the feasibility of storing hydrogen in pipeline bundles located in proximity of offshore windfarms and covers six tasks, all the way from pre-feasibility to an evaluation study.
Task 1 consisted in conducting a prefeasibility study, including a brief investigation into the potential amount of hydrogen to be stored within the pipeline bundles. For this, the number of bundles, lengths, widths and overall sizes were estimated, and the conditions required for repurposing bundles was outlined. This was followed by Task 2 which comprised extensive data collection.
Currently, the project is undergoing Task 3 involving mapping of bundles. This is allowing the Integrated Energy team to undertake a preliminary scope of bundles’ proximity to offshore wind farms.
Future Tasks 4-6 are set to include a full investigation of the repurposing of bundles and a wider pipeline scope including coatings for pipeline repurposing, fatigue cycles, cleaning, services and hydrogen compatibility with coatings. In addition to this, an expanded mapping task will allow the team to develop a comprehensive and layered map with all assets included. And the final stage will conclude the feasibility study with the inclusion of the costing evaluation.
Some challenges have already been identified:
- The ability to accurately map all the different points and offshore assets within the North Sea
- The data availability has proven difficult and not 100% accurate
- Not all bundles are closely aligned to current and new offshore wind farms, meaning the scope needs to focus on specific bundles and potentially widen to include other types of pipelines
To date, the project has enabled the team to conclude that bundles do have the potential to store hydrogen with only slight modifications, to existing infield bundles. The process of repurposing the pipeline bundles will be explored within further research.
Opportunities lie with many bundles which will require decommissioning, new and current wind farms and even platforms that could be repurposed to produce and process hydrogen offshore.
It is noted that the investigation into pipeline bundle repurposing is just in its early stages and that a more detailed mapping exercise is required; however further research promises real opportunities in the North Sea and further afield for affordable H2 storage solutions.
To discover more about how our Integrated Energy team is solving real-world problems and the other impactful research projects that are currently being undertaken, view our dedicated Integrated Energy webpage.
