Life-cycle global warming impact of hydrogen transport through pipelines from Africa to Germany

Various hydrogen pipeline structures for the export of hydrogen from Africa to Germany are analyzed by life cycle analysis (LCA) in order to determine the global warming potential (GWP) of the production and transportation of 1 kg of hydrogen. This analysis was motivated by the fact that a hydrogen pipeline infrastructure can be built cost-effectively by partially using existing natural gas pipelines. However, little is known about its possible environmental impact. In this paper, the LCA method is used to compare different import options, including possible changes to future supply chains. Three supply locations - Morocco, Senegal, and Nigeria - are compared with each other and evaluated using Germany's domestic hydrogen supply as a reference. Hydrogen transport via a pipeline from Morocco shows emissions of 0.07-0.11 kg CO2-eq per kg H-2, and hydrogen transport from Nigeria causes emissions of 0.27-0.38 kg CO2-eq per kg H-2. These figures are highly dependent on the flow rate of hydrogen, the GWP of PV electricity used to power the hydrogen compressors along the way, and compression efficiency. However, the GWP due to pipeline transport is negligible compared to the emissions caused by PV electrolysis. The total emissions of the African supply chain amount to 1.9-2.5 kg CO2-eq per kg H-2. From a sensitivity analysis, it can be concluded that, by using identical PV panels, the GWP of German domestic hydrogen production (3.0-3.1 kg CO2-eq per kg H-2) still has a higher GWP than hydrogen produced in Africa and imported through pipeline supply chains.