Reusing existing inland pipelines for hydrogen transportation is a topic of growing interest, especially as countries explore ways to decarbonize energy systems and support the hydrogen economy. Here are some key aspects of reusing pipelines for hydrogen transport:

1. Suitability of Existing Pipelines

• Materials and Integrity: Pipelines originally designed for natural gas or oil may be made of materials that are susceptible to hydrogen embrittlement, a phenomenon where hydrogen weakens the metal, potentially causing leaks or fractures. Not all pipelines are suitable for hydrogen transport without modification.
• Age of Pipelines: Older pipelines may not be as durable or suitable for conversion due to the wear and tear they’ve experienced over time.
• Pipeline Pressure: Hydrogen requires different pressure levels than natural gas, as it has different properties, like being less dense, meaning a higher volume must be transported to achieve equivalent energy output.

2. Technical Modifications

• Material Upgrades: Some pipelines may require lining or coating with hydrogen-resistant materials, or may need to be replaced altogether.
• Compressor Stations: Hydrogen molecules are smaller than natural gas molecules, which means more frequent and specialized compressor stations might be needed to maintain pressure and control hydrogen flow through the network.
• Monitoring and Leak Detection: Because hydrogen is more prone to leaks, advanced monitoring systems may need to be installed to detect small leaks that might be more difficult to spot than with natural gas.

3. Blending Hydrogen with Natural Gas

• One approach is to blend hydrogen into existing natural gas pipelines. Many studies suggest that up to 20% hydrogen can be mixed with natural gas without significant infrastructure changes. This method helps introduce hydrogen into the energy system gradually while utilizing current pipeline infrastructure.

4. Cost Implications

• Retrofitting existing pipelines is generally more cost-effective than building new hydrogen-specific pipelines. However, the extent of required modifications can significantly impact costs. Proper assessments of pipeline condition and the scope of needed changes are necessary.

5. Safety Considerations

• Hydrogen is more flammable and has a broader range of explosive concentrations compared to natural gas, meaning extra safety measures must be in place. Pipeline operators need to ensure proper risk management, which could include adjusting the design of valves and sensors, and enhancing emergency response protocols.

6. Regulatory and Standardization Issues

• As hydrogen infrastructure grows, standards and regulations need to be developed to ensure safe and efficient transport. Many countries are now working on regulatory frameworks for hydrogen pipelines, but uniform standards are still evolving.

7. Environmental Benefits

• Using hydrogen, especially green hydrogen (produced from renewable energy), in repurposed pipelines can contribute significantly to the decarbonization of industrial sectors and energy grids. Reusing pipelines can also reduce the need for new infrastructure, minimizing environmental disruption.

8. Pilot Projects and Success Stories

• Several countries and companies are already experimenting with hydrogen pipelines. For example, in Germany, natural gas pipelines have been tested for hydrogen blending, and in the Netherlands, some industrial areas are being equipped for hydrogen transport using existing pipelines.

Reusing inland pipelines for hydrogen transport offers a pragmatic approach to accelerating the hydrogen economy but requires careful technical, economic, and safety evaluations before large-scale implementation.