Hydrogen transport in large-scale transmission pipeline networks: Thermodynamic and environmental assessment of repurposed and new pipeline configurations

Abstract

One key strategy to achieve global climate targets is implementing climate-friendly hydrogen as a versatile energy carrier, commodity, and feedstock in the most energy-intensive sectors. Transmission pipeline networks are suited particularly for connecting primary hydrogen producers and consumers over medium distances to meet the future hydrogen demand in regions that strongly rely on energy imports. Nonetheless, the development and operation of large-scale hydrogen pipeline networks may have various yet unknown impacts on the environment. This work investigates the energetic efficiency and the environmental performance of hydrogen transport via pipeline by means of thermodynamic analysis and life cycle assessment. Pertinent technical specifications for large-scale hydrogen pipeline networks were derived based on the current design of state-of-the-art hydrogen pipelines and compressor stations. Since the energy-efficient operation of the pipeline network is essential for a climate-friendly hydrogen transport, thermodynamic analyses were performed to determine the resulting energy demand. Depending on the impact category considered, there are advantages and trade-offs in aiming for an energy-efficient as well as environmentally friendly hydrogen transport solution. The most decisive parameters to reach these aims are the condition of the line pipe’s inner layer, the applied load capacity, as well as the compression ratios, -stages and -positioning. By varying these parameters and considering multiple transport variants, we recommend three measures for the design and operation of new or repurposed hydrogen pipelines: 1) Installing new smooth line pipes or cleaning existing ones to minimize the roughness of the inner surface; 2) Moderately reducing the load capacity, and 3) Shortening the transport intervals by installing intermediate compressor stations. Ultimately, reducing pressure losses within the pipeline system is crucial for ensuring an energetically efficient as well as environmentally friendly hydrogen transmission via large-scale pipeline networks.