Blog: Hydrogen blend in the gas grid - four challenges and solutions

1. Hydrogen embrittlement 

Hydrogen embrittlement is a process where some metals become brittle and prone to cracking after being exposed to hydrogen. Because hydrogen atoms are incredibly small, they can easily diffuse into a metal’s structure, with certain materials being especially susceptible to damage. 

For example, high-strength steels, which are commonly used in pipelines and storage tanks, are particularly at risk from hydrogen embrittlement. Other alloys like nickel, titanium and aluminium can be affected too, but to varying degrees. 

As such, this is a serious consideration for natural gas infrastructure. Over time, hydrogen embrittlement could lead to cracks or leaks in pipelines, potentially causing safety risks and resulting in significant service disruptions. 

Hydrogen embrittlement could also cause damage to storage tanks. Should one of these rupture, then hydrogen would be released at a large scale. Alternatively, using hydrogen blend in the gas network may mean tanks need to be operated at lower pressures, to minimise opportunities for embrittlement to occur. However, this has an impact too, with lower storage capacities. 

How can hydrogen embrittlement risks be mitigated? 

Material selection is key. Some grades of stainless steel and composite materials protect against hydrogen embrittlement. Special coatings are also available that can be applied, preventing hydrogen from entering metals. 

Controlling operating conditions like temperature and pressure can also help reduce hydrogen embrittlement. Meanwhile, inspection methods such as ultrasonic testing can ensure this risk isn’t becoming a problem. 

Reducing the amount of hydrogen that’s blended into the gas network is another means of limiting opportunities for embrittlement. Considering the impact of different levels of hydrogen blend into the gas grid is something we'll discuss in another blog. 

2. Hydrogen leaks 

Hydrogen’s small molecular size also makes it more prone to leaks than methane. Should small cracks begin to appear in pipelines or storage facilities, then there’s the chance for increased leakages. Its low viscosity contributes towards this risk too, making hydrogen more difficult to contain - especially in older infrastructure originally designed solely for natural gas. 

From microscopic cracks in pipelines or storage tanks, to faulty fittings or joints that make it easier for hydrogen to escape, hydrogen leaks pose a serious risk that needs to be well thought out if we’re to integrate hydrogen into energy systems like the gas grid. 

How are hydrogen leaks best addressed? 

Similar to the risks posed by hydrogen embrittlement, leaks are best tackled by choosing the right infrastructure materials. Materials with low hydrogen permeability, such as certain grades of stainless steel or specialised polymers, are one possible solution. Regular inspections that take advantage of techniques like ultrasonic testing can also help detect potential leak points, so these can be remedied before they become a bigger problem. 

Sensor networks and smart monitoring systems can also help continuously monitor for leaks, using data analytics and artificial intelligence to pinpoint patterns and identify where potential leaks might occur in the future. 

3. Gas composition changes 

Introducing hydrogen into the gas network’s existing infrastructure will also change the composition of the gas mixture. With its physical and chemical properties altered, this will have a number of network implications. 

For instance, hydrogen has a wider flammability range than methane. Hydrogen also burns differently to natural gas, which could affect the performance of certain appliances. 

Some parts of the gas network or storage facilities may need to be upgraded or replaced to accommodate this new gas composition, with sophisticated monitoring and control systems required to make sure the correct gas composition and quality levels are maintained. 

How can these gas composition changes be controlled? 

Developing and enforcing strict safety standards for hydrogen production, storage, transportation and use will be paramount. This means establishing clear standards for gas quality, infrastructure design and appliance compatibility. 

In addition, investing in ongoing research will allow us to better understand the behaviour of hydrogen in the gas grid. As the hydrogen economy gains pace, this will become increasingly important. 

4. Compression demands 

Hydrogen's lower density demands more energy for compression, making it crucial to optimise these processes and minimise energy consumption in a decarbonised gas network. 

One impact is that greater energy requirements for compression could increase operating costs. Another consideration is that if the energy used for compression comes from fossil fuels, it can increase greenhouse gas emissions, undermining the environmental benefits of using hydrogen. 

The need for more powerful compressors and potential pipeline modifications could limit the capacity of the existing gas network to transport hydrogen, too. 

How can compression demands be overcome? 

One option is to develop and deploy compressors that are specifically designed for hydrogen, with improved efficiency and material compatibility. This includes exploring technologies like ionic liquid piston compressors, electrochemical compressors and metal hydride compressors. 

There’s also the chance to enhance compression processes by using multi-stage compression or heat recovery technologies, to further improve their overall efficiency levels. 

Where possible, it also makes sense to use renewable energy sources like solar or wind power to drive compressors, reducing the reliance on fossil fuels and lowering carbon emissions in the process. 

Paving the way towards a hydrogen-powered future

There’s no doubt that adapting Great Britain’s gas grid for hydrogen blend is a complex undertaking. Yet, with innovation and collaboration, these challenges can be overcome. 

By investing in research, upgrading infrastructure and implementing robust safety measures, there’s the potential for hydrogen blending to help revolutionise the energy system and forge a cleaner, more sustainable future. 

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